An input/output controller for virtual pinball machines, with plunger position tracking, accelerometer-based nudge sensing, button input encoding, and feedback device control.

Dependencies:   USBDevice mbed FastAnalogIn FastIO FastPWM SimpleDMA

/media/uploads/mjr/pinscape_no_background_small_L7Miwr6.jpg

The Pinscape Controller is a special-purpose software project that I wrote for my virtual pinball machine.

New version: V2 is now available! The information below is for version 1, which will continue to be available for people who prefer the original setup.

What exactly is a virtual pinball machine? It's basically a video-game pinball emulator built to look like a real pinball machine. (The picture at right is the one I built.) You start with a standard pinball cabinet, either built from scratch or salvaged from a real machine. Inside, you install a PC motherboard to run the software, and install TVs in place of the playfield and backglass. Several Windows pinball programs can take advantage of this setup, including the open-source project Visual Pinball, which has hundreds of tables available. Building one of these makes a great DIY project, and it's a good way to add to your skills at woodworking, computers, and electronics. Check out the Cabinet Builders' Forum on vpforums.org for lots of examples and advice.

This controller project is a key piece in my setup that helps integrate the video game into the pinball cabinet. It handles several input/output tasks that are unique to virtual pinball machines. First, it lets you connect a mechanical plunger to the software, so you can launch the ball like on a real machine. Second, it sends "nudge" data to the software, based on readings from an accelerometer. This lets you interact with the game physically, which makes the playing experience more realistic and immersive. Third, the software can handle button input (for wiring flipper buttons and other cabinet buttons), and fourth, it can control output devices (for tactile feedback, button lights, flashers, and other special effects).

Documentation

The Hardware Build Guide (PDF) has detailed instructions on how to set up a Pinscape Controller for your own virtual pinball cabinet.

Update notes

December 2015 version: This version fully supports the new Expansion Board project, but it'll also run without it. The default configuration settings haven't changed, so existing setups should continue to work as before.

August 2015 version: Be sure to get the latest version of the Config Tool for windows if you're upgrading from an older version of the firmware. This update adds support for TSL1412R sensors (a version of the 1410 sensor with a slightly larger pixel array), and a config option to set the mounting orientation of the board in the firmware rather than in VP (for better support for FP and other pinball programs that don't have VP's flexibility for setting the rotation).

Feb/March 2015 software versions: If you have a CCD plunger that you've been using with the older versions, and the plunger stops working (or doesn't work as well) after you update to the latest version, you might need to increase the brightness of your light source slightly. Check the CCD exposure with the Windows config tool to see if it looks too dark. The new software reads the CCD much more quickly than the old versions did. This makes the "shutter speed" faster, which might require a little more light to get the same readings. The CCD is actually really tolerant of varying light levels, so you probably won't have to change anything for the update - I didn't. But if you do have any trouble, have a look at the exposure meter and try a slightly brighter light source if the exposure looks too dark.

Downloads

  • Config tool for Windows (.exe and C# source): this is a Windows program that lets you view the raw pixel data from the CCD sensor, trigger plunger calibration mode, and configure some of the software options on the controller.
  • Custom VP builds: I created modified versions of Visual Pinball 9.9 and Physmod5 that you might want to use in combination with this controller. The modified versions have special handling for plunger calibration specific to the Pinscape Controller, as well as some enhancements to the nudge physics. If you're not using the plunger, you might still want it for the nudge improvements. The modified version also works with any other input controller, so you can get the enhanced nudging effects even if you're using a different plunger/nudge kit. The big change in the modified versions is a "filter" for accelerometer input that's designed to make the response to cabinet nudges more realistic. It also makes the response more subdued than in the standard VP, so it's not to everyone's taste. The downloads include both the updated executables and the source code changes, in case you want to merge the changes into your own custom version(s).

    Note! These features are now standard in the official VP 9.9.1 and VP 10 releases, so you don't need my custom builds if you're using 9.9.1 or 10 or later. I don't think there's any reason to use my 9.9 instead of the official 9.9.1, but I'm leaving it here just in case. In the official VP releases, look for the checkbox "Enable Nudge Filter" in the Keys preferences dialog. (There's no checkbox in my custom builds, though; the filter is simply always on in those.)
  • Output circuit shopping list: This is a saved shopping cart at mouser.com with the parts needed for each output driver, if you want to use the LedWiz emulator feature. Note that quantities in the cart are for one output channel, so multiply everything by the number of channels you plan to use, except that you only need one of the ULN2803 transistor array chips for each eight output circuits.
  • Lemming77's potentiometer mounting bracket and shooter rod connecter: Sketchup designs for 3D-printable parts for mounting a slide potentiometer as the plunger sensor. These were designed for a particular slide potentiometer that used to be available from an Aliexpress.com seller but is no longer listed. You can probably use this design as a starting point for other similar devices; just check the dimensions before committing the design to plastic.

Features

  • Plunger position sensing, using a TAOS TSL 1410R CCD linear array sensor. This sensor is a 1280 x 1 pixel array at 400 dpi, which makes it about 3" long - almost exactly the travel distance of a standard pinball plunger. The idea is that you install the sensor just above (within a few mm of) the shooter rod on the inside of the cabinet, with the CCD window facing down, aligned with and centered on the long axis of the shooter rod, and positioned so that the rest position of the tip is about 1/2" from one end of the window. As you pull back the plunger, the tip will travel down the length of the window, and the maximum retraction point will put the tip just about at the far end of the window. Put a light source below, facing the sensor - I'm using two typical 20 mA blue LEDs about 8" away (near the floor of the cabinet) with good results. The principle of operation is that the shooter rod casts a shadow on the CCD, so pixels behind the rod will register lower brightness than pixels that aren't in the shadow. We scan down the length of the sensor for the edge between darker and brighter, and this tells us how far back the rod has been pulled. We can read the CCD at about 25-30 ms intervals, so we can get rapid updates. We pass the readings reports to VP via our USB joystick reports.

    The hardware build guide includes schematics showing how to wire the CCD to the KL25Z. It's pretty straightforward - five wires between the two devices, no external components needed. Two GPIO ports are used as outputs to send signals to the device and one is used as an ADC in to read the pixel brightness inputs. The config tool has a feature that lets you display the raw pixel readings across the array, so you can test that the CCD is working and adjust the light source to get the right exposure level.

    Alternatively, you can use a slide potentiometer as the plunger sensor. This is a cheaper and somewhat simpler option that seems to work quite nicely, as you can see in Lemming77's video of this setup in action. This option is also explained more fully in the build guide.
  • Nudge sensing via the KL25Z's on-board accelerometer. Mounting the board in your cabinet makes it feel the same accelerations the cabinet experiences when you nudge it. Visual Pinball already knows how to interpret accelerometer input as nudging, so we simply feed the acceleration readings to VP via the joystick interface.
  • Cabinet button wiring. Up to 24 pushbuttons and switches can be wired to the controller for input controls (for example, flipper buttons, the Start button, the tilt bob, coin slot switches, and service door buttons). These appear to Windows as joystick buttons. VP can map joystick buttons to pinball inputs via its keyboard preferences dialog. (You can raise the 24-button limit by editing the source code, but since all of the GPIO pins are allocated, you'll have to reassign pins currently used for other functions.)
  • LedWiz emulation (limited). In addition to emulating a joystick, the device emulates the LedWiz USB interface, so controllers on the PC side such as DirectOutput Framework can recognize it and send it commands to control lights, solenoids, and other feedback devices. 22 GPIO ports are assigned by default as feedback device outputs. This feature has some limitations. The big one is that the KL25Z hardware only has 10 PWM channels, which isn't enough for a fully decked-out cabinet. You also need to build some external power driver circuitry to use this feature, because of the paltry 4mA output capacity of the KL25Z GPIO ports. The build guide includes instructions for a simple and robust output circuit, including part numbers for the exact components you need. It's not hard if you know your way around a soldering iron, but just be aware that it'll take a little work.

Warning: This is not replacement software for the VirtuaPin plunger kit. If you bought the VirtuaPin kit, please don't try to install this software. The VP kit happens to use the same microcontroller board, but the rest of its hardware is incompatible. The VP kit uses a different type of sensor for its plunger and has completely different button wiring, so the Pinscape software won't work properly with it.

Files at this revision

API Documentation at this revision

Comitter:
mjr
Date:
Wed Jul 16 23:33:12 2014 +0000
Parent:
0:5acbbe3f4cf4
Child:
2:c174f9ee414a
Commit message:
Before removing time/frequency limit on reading the plunger sensor

Changed in this revision

FreescaleIAP.cpp Show annotated file Show diff for this revision Revisions of this file
FreescaleIAP.h Show annotated file Show diff for this revision Revisions of this file
MMA8451Q.lib Show diff for this revision Revisions of this file
MMA8451Q/MMA8451Q.cpp Show annotated file Show diff for this revision Revisions of this file
MMA8451Q/MMA8451Q.h Show annotated file Show diff for this revision Revisions of this file
USBJoystick.cpp Show annotated file Show diff for this revision Revisions of this file
main.cpp Show annotated file Show diff for this revision Revisions of this file
tls1410r.cpp Show diff for this revision Revisions of this file
tls1410r.h Show diff for this revision Revisions of this file
tsl1410r.h Show annotated file Show diff for this revision Revisions of this file
tsl410r.cpp Show annotated file Show diff for this revision Revisions of this file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/FreescaleIAP.cpp	Wed Jul 16 23:33:12 2014 +0000
@@ -0,0 +1,190 @@
+#include "FreescaleIAP.h"
+ 
+//#define IAPDEBUG
+ 
+enum FCMD {
+    Read1s = 0x01,
+    ProgramCheck = 0x02,
+    ReadResource = 0x03,
+    ProgramLongword = 0x06,
+    EraseSector = 0x09,
+    Read1sBlock = 0x40,
+    ReadOnce = 0x41,
+    ProgramOnce = 0x43,
+    EraseAll = 0x44,
+    VerifyBackdoor = 0x45
+    };
+ 
+inline void run_command(void);
+bool check_boundary(int address, unsigned int length);
+bool check_align(int address);
+IAPCode verify_erased(int address, unsigned int length);
+IAPCode check_error(void);
+IAPCode program_word(int address, char *data);IAPCode program_word(int address, char *data);
+    
+IAPCode erase_sector(int address) {
+    #ifdef IAPDEBUG
+    printf("IAP: Erasing at %x\r\n", address);
+    #endif
+    if (check_align(address))
+        return AlignError;
+    
+    //Setup command
+    FTFA->FCCOB0 = EraseSector;
+    FTFA->FCCOB1 = (address >> 16) & 0xFF;
+    FTFA->FCCOB2 = (address >> 8) & 0xFF;
+    FTFA->FCCOB3 = address & 0xFF;
+    
+    run_command();
+    
+    return check_error();
+}
+ 
+IAPCode program_flash(int address, char *data, unsigned int length) {
+    #ifdef IAPDEBUG
+    printf("IAP: Programming flash at %x with length %d\r\n", address, length);
+    #endif
+    if (check_align(address))
+        return AlignError;
+        
+    IAPCode eraseCheck = verify_erased(address, length);
+    if (eraseCheck != Success)
+        return eraseCheck;
+    
+    IAPCode progResult;
+    for (int i = 0; i < length; i+=4) {
+        progResult = program_word(address + i, data + i);
+        if (progResult != Success)
+            return progResult;
+    }
+    
+    return Success;
+}
+ 
+uint32_t flash_size(void) {
+    uint32_t retval = (SIM->FCFG2 & 0x7F000000u) >> (24-13);
+    if (SIM->FCFG2 & (1<<23))           //Possible second flash bank
+        retval += (SIM->FCFG2 & 0x007F0000u) >> (16-13);
+    return retval;
+}
+ 
+IAPCode program_word(int address, char *data) {
+    #ifdef IAPDEBUG
+    printf("IAP: Programming word at %x, %d - %d - %d - %d\r\n", address, data[0], data[1], data[2], data[3]);
+    #endif
+    if (check_align(address))
+        return AlignError;
+    
+    //Setup command
+    FTFA->FCCOB0 = ProgramLongword;
+    FTFA->FCCOB1 = (address >> 16) & 0xFF;
+    FTFA->FCCOB2 = (address >> 8) & 0xFF;
+    FTFA->FCCOB3 = address & 0xFF;
+    FTFA->FCCOB4 = data[3];
+    FTFA->FCCOB5 = data[2];
+    FTFA->FCCOB6 = data[1];
+    FTFA->FCCOB7 = data[0];
+    
+    run_command();
+    
+    return check_error();
+}
+ 
+/* Clear possible flags which are set, run command, wait until done */
+inline void run_command(void) {
+    //Clear possible old errors, start command, wait until done
+    FTFA->FSTAT = FTFA_FSTAT_FPVIOL_MASK | FTFA_FSTAT_ACCERR_MASK | FTFA_FSTAT_RDCOLERR_MASK;
+    FTFA->FSTAT = FTFA_FSTAT_CCIF_MASK;
+    while (!(FTFA->FSTAT & FTFA_FSTAT_CCIF_MASK));
+}    
+    
+    
+ 
+/* Check if no flash boundary is violated
+   Returns true on violation */
+bool check_boundary(int address, unsigned int length) {
+    int temp = (address+length - 1) / SECTOR_SIZE;
+    address /= SECTOR_SIZE;
+    bool retval = (address != temp);
+    #ifdef IAPDEBUG
+    if (retval)
+        printf("IAP: Boundary violation\r\n");
+    #endif
+    return retval;
+}
+ 
+/* Check if address is correctly aligned
+   Returns true on violation */
+bool check_align(int address) {
+    bool retval = address & 0x03;
+    #ifdef IAPDEBUG
+    if (retval)
+        printf("IAP: Alignment violation\r\n");
+    #endif
+    return retval;
+}
+ 
+/* Check if an area of flash memory is erased
+   Returns error code or Success (in case of fully erased) */
+IAPCode verify_erased(int address, unsigned int length) {
+    #ifdef IAPDEBUG
+    printf("IAP: Verify erased at %x with length %d\r\n", address, length);
+    #endif
+    
+    if (check_align(address))
+        return AlignError;
+    
+    //Setup command
+    FTFA->FCCOB0 = Read1s;
+    FTFA->FCCOB1 = (address >> 16) & 0xFF;
+    FTFA->FCCOB2 = (address >> 8) & 0xFF;
+    FTFA->FCCOB3 = address & 0xFF;
+    FTFA->FCCOB4 = (length >> 10) & 0xFF;
+    FTFA->FCCOB5 = (length >> 2) & 0xFF;
+    FTFA->FCCOB6 = 0;
+    
+    run_command();
+    
+    IAPCode retval = check_error();
+    if (retval == RuntimeError) {
+        #ifdef IAPDEBUG
+        printf("IAP: Flash was not erased\r\n");
+        #endif
+        return EraseError;
+    }
+    return retval;
+        
+}
+ 
+/* Check if an error occured 
+   Returns error code or Success*/
+IAPCode check_error(void) {
+    if (FTFA->FSTAT & FTFA_FSTAT_FPVIOL_MASK) {
+        #ifdef IAPDEBUG
+        printf("IAP: Protection violation\r\n");
+        #endif
+        return ProtectionError;
+    }
+    if (FTFA->FSTAT & FTFA_FSTAT_ACCERR_MASK) {
+        #ifdef IAPDEBUG
+        printf("IAP: Flash access error\r\n");
+        #endif
+        return AccessError;
+    }
+    if (FTFA->FSTAT & FTFA_FSTAT_RDCOLERR_MASK) {
+        #ifdef IAPDEBUG
+        printf("IAP: Collision error\r\n");
+        #endif
+        return CollisionError;
+    }
+    if (FTFA->FSTAT & FTFA_FSTAT_MGSTAT0_MASK) {
+        #ifdef IAPDEBUG
+        printf("IAP: Runtime error\r\n");
+        #endif
+        return RuntimeError;
+    }
+    #ifdef IAPDEBUG
+    printf("IAP: No error reported\r\n");
+    #endif
+    return Success;
+}
\ No newline at end of file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/FreescaleIAP.h	Wed Jul 16 23:33:12 2014 +0000
@@ -0,0 +1,87 @@
+/*
+ *  Freescale FTFA Flash Memory programmer
+ *
+ *  Sample usage:
+
+#include "mbed.h"
+#include "FreescaleIAP.h"
+  
+int main() {
+    int address = flash_size() - SECTOR_SIZE;           //Write in last sector
+    
+    int *data = (int*)address;
+    printf("Starting\r\n"); 
+    erase_sector(address);
+    int numbers[10] = {0, 1, 10, 100, 1000, 10000, 1000000, 10000000, 100000000, 1000000000};
+    program_flash(address, (char*)&numbers, 40);        //10 integers of 4 bytes each: 40 bytes length
+    printf("Resulting flash: \r\n");
+    for (int i = 0; i<10; i++)
+        printf("%d\r\n", data[i]);
+    
+    printf("Done\r\n\n");
+        
+ 
+    while (true) {
+    }
+}
+
+*/
+
+#ifndef FREESCALEIAP_H
+#define FREESCALEIAP_H
+ 
+#include "mbed.h"
+ 
+#ifdef TARGET_KLXX
+#define SECTOR_SIZE     1024
+#elif TARGET_K20D5M
+#define SECTOR_SIZE     2048
+#elif TARGET_K64F
+#define SECTOR_SIZE     4096
+#else
+#define SECTOR_SIZE     1024
+#endif
+ 
+enum IAPCode {
+    BoundaryError = -99,    //Commands may not span several sectors
+    AlignError,             //Data must be aligned on longword (two LSBs zero)
+    ProtectionError,        //Flash sector is protected
+    AccessError,            //Something went wrong
+    CollisionError,         //During writing something tried to flash which was written to
+    LengthError,            //The length must be multiples of 4
+    RuntimeError,           
+    EraseError,             //The flash was not erased before writing to it
+    Success = 0
+    };
+ 
+/** Erase a flash sector
+ *
+ * The size erased depends on the used device
+ *
+ * @param address address in the sector which needs to be erased
+ * @param return Success if no errors were encountered, otherwise one of the error states
+ */
+IAPCode erase_sector(int address);
+ 
+/** Program flash
+ *
+ * Before programming the used area needs to be erased. The erase state is checked
+ * before programming, and will return an error if not erased.
+ *
+ * @param address starting address where the data needs to be programmed (must be longword alligned: two LSBs must be zero)
+ * @param data pointer to array with the data to program
+ * @param length number of bytes to program (must be a multiple of 4)
+ * @param return Success if no errors were encountered, otherwise one of the error states
+ */
+IAPCode program_flash(int address, char *data, unsigned int length);
+ 
+/**
+ * Returns size of flash memory
+ * 
+ * This is the first address which is not flash
+ *
+ * @param return length of flash memory in bytes
+ */
+uint32_t flash_size(void);
+ 
+#endif
--- a/MMA8451Q.lib	Fri Jul 11 03:26:11 2014 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,1 +0,0 @@
-http://mbed.org/users/emilmont/code/MMA8451Q/#c4d879a39775
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MMA8451Q/MMA8451Q.cpp	Wed Jul 16 23:33:12 2014 +0000
@@ -0,0 +1,176 @@
+/* Copyright (c) 2010-2011 mbed.org, MIT License
+*
+* Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+* and associated documentation files (the "Software"), to deal in the Software without
+* restriction, including without limitation the rights to use, copy, modify, merge, publish,
+* distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the
+* Software is furnished to do so, subject to the following conditions:
+*
+* The above copyright notice and this permission notice shall be included in all copies or
+* substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
+* BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+#include "MMA8451Q.h"
+
+#define REG_WHO_AM_I      0x0D
+#define REG_CTRL_REG_1    0x2A
+#define REG_CTRL_REG_2    0x2B
+#define REG_CTRL_REG_3    0x2c
+#define REG_CTRL_REG_4    0x2D
+#define REG_CTRL_REG_5    0x2E
+#define REG_OFF_X         0x2F
+#define REG_OFF_Y         0x30
+#define REG_OFF_Z         0x31
+#define XYZ_DATA_CFG_REG  0x0E
+#define REG_OUT_X_MSB     0x01
+#define REG_OUT_Y_MSB     0x03
+#define REG_OUT_Z_MSB     0x05
+
+#define UINT14_MAX        16383
+
+#define CTL_ACTIVE        0x01
+#define FS_MASK           0x03
+#define FS_2G             0x00
+#define FS_4G             0x01
+#define FS_8G             0x02
+
+#define HPF_OUT_MASK      0x10
+
+#define MODS1_MASK        0x02
+#define MODS0_MASK        0x01
+#define SMODS_MASK        0x18
+#define MODS_MASK         0x03
+
+#define DR_MASK           0x38
+#define DR_800_HZ         0x00
+#define DR_400_HZ         0x08
+#define DR_200_HZ         0x10
+#define DR_100_HZ         0x18
+#define DR_50_HZ          0x20
+#define DR_12_HZ          0x28
+#define DR_6_HZ           0x30
+#define DR_1_HZ           0x38
+
+
+MMA8451Q::MMA8451Q(PinName sda, PinName scl, int addr) : m_i2c(sda, scl), m_addr(addr) 
+{
+    // go to standby mode
+    standby();
+    
+    // read the curent config register
+    uint8_t d1[1];
+    readRegs(XYZ_DATA_CFG_REG, d1, 1);
+    
+    // set 2g mode
+    uint8_t d2[2] = { XYZ_DATA_CFG_REG, (d1[0] & ~FS_MASK) | FS_2G };
+    writeRegs(d2, 2);
+    
+    // read the ctl2 register
+    uint8_t d3[1];
+    readRegs(REG_CTRL_REG_2, d3, 1);
+    
+    // set the high resolution mode
+    uint8_t d4[2] = {REG_CTRL_REG_2, (d3[0] & ~MODS_MASK) | MODS1_MASK};
+    writeRegs(d4, 2);
+    
+    // set 50 Hz mode
+    uint8_t d5[1];
+    readRegs(REG_CTRL_REG_1, d5, 1);
+    
+    uint8_t d6[2] = {REG_CTRL_REG_1, (d5[0] & ~DR_MASK) | DR_100_HZ};
+    writeRegs(d6, 2);
+    
+    // enter active mode
+    active();
+}
+
+MMA8451Q::~MMA8451Q() { }
+
+void MMA8451Q::standby()
+{
+    // read the current control register
+    uint8_t d1[1];
+    readRegs(REG_CTRL_REG_1, d1, 1);
+    
+    // write it back witht he Active bit cleared
+    uint8_t d2[2] = { REG_CTRL_REG_1, d1[0] & ~CTL_ACTIVE };
+    writeRegs(d2, 2);
+}
+
+void MMA8451Q::active()
+{
+    // read the current control register
+    uint8_t d1[1];
+    readRegs(REG_CTRL_REG_1, d1, 1);
+    
+    // write it back out with the Active bit set
+    uint8_t d2[2] = { REG_CTRL_REG_1, d1[0] | CTL_ACTIVE };
+    writeRegs(d2, 2);
+}
+
+uint8_t MMA8451Q::getWhoAmI() {
+    uint8_t who_am_i = 0;
+    readRegs(REG_WHO_AM_I, &who_am_i, 1);
+    return who_am_i;
+}
+
+float MMA8451Q::getAccX() {
+    return (float(getAccAxis(REG_OUT_X_MSB))/4096.0);
+}
+
+void MMA8451Q::getAccXY(float &x, float &y) 
+{
+    // read the X and Y output registers
+    uint8_t res[4];
+    readRegs(REG_OUT_X_MSB, res, 4);
+    
+    // translate the x value
+    uint16_t acc = (res[0] << 8) | (res[1]);
+    x = int16_t(acc)/(4*4096.0);
+    
+    // translate the y value
+    acc = (res[2] << 9) | (res[3]);
+    y = int16_t(acc)/(4*4096.0);
+}
+
+float MMA8451Q::getAccY() {
+    return (float(getAccAxis(REG_OUT_Y_MSB))/4096.0);
+}
+
+float MMA8451Q::getAccZ() {
+    return (float(getAccAxis(REG_OUT_Z_MSB))/4096.0);
+}
+
+void MMA8451Q::getAccAllAxis(float * res) {
+    res[0] = getAccX();
+    res[1] = getAccY();
+    res[2] = getAccZ();
+}
+
+int16_t MMA8451Q::getAccAxis(uint8_t addr) {
+    int16_t acc;
+    uint8_t res[2];
+    readRegs(addr, res, 2);
+
+    acc = (res[0] << 6) | (res[1] >> 2);
+    if (acc > UINT14_MAX/2)
+        acc -= UINT14_MAX;
+
+    return acc;
+}
+
+void MMA8451Q::readRegs(int addr, uint8_t * data, int len) {
+    char t[1] = {addr};
+    m_i2c.write(m_addr, t, 1, true);
+    m_i2c.read(m_addr, (char *)data, len);
+}
+
+void MMA8451Q::writeRegs(uint8_t * data, int len) {
+    m_i2c.write(m_addr, (char *)data, len);
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MMA8451Q/MMA8451Q.h	Wed Jul 16 23:33:12 2014 +0000
@@ -0,0 +1,125 @@
+/* Copyright (c) 2010-2011 mbed.org, MIT License
+*
+* Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+* and associated documentation files (the "Software"), to deal in the Software without
+* restriction, including without limitation the rights to use, copy, modify, merge, publish,
+* distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the
+* Software is furnished to do so, subject to the following conditions:
+*
+* The above copyright notice and this permission notice shall be included in all copies or
+* substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
+* BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+#ifndef MMA8451Q_H
+#define MMA8451Q_H
+
+#include "mbed.h"
+
+/**
+* MMA8451Q accelerometer example
+*
+* @code
+* #include "mbed.h"
+* #include "MMA8451Q.h"
+* 
+* #define MMA8451_I2C_ADDRESS (0x1d<<1)
+* 
+* int main(void) {
+* 
+* MMA8451Q acc(P_E25, P_E24, MMA8451_I2C_ADDRESS);
+* PwmOut rled(LED_RED);
+* PwmOut gled(LED_GREEN);
+* PwmOut bled(LED_BLUE);
+* 
+*     while (true) {       
+*         rled = 1.0 - abs(acc.getAccX());
+*         gled = 1.0 - abs(acc.getAccY());
+*         bled = 1.0 - abs(acc.getAccZ());
+*         wait(0.1);
+*     }
+* }
+* @endcode
+*/
+class MMA8451Q
+{
+public:
+  /**
+  * MMA8451Q constructor
+  *
+  * @param sda SDA pin
+  * @param sdl SCL pin
+  * @param addr addr of the I2C peripheral
+  */
+  MMA8451Q(PinName sda, PinName scl, int addr);
+
+  /**
+  * MMA8451Q destructor
+  */
+  ~MMA8451Q();
+
+  /**
+   * Enter standby mode
+   */
+  void standby();
+  
+  /**
+   * Enter active mode
+   */
+  void active();
+  
+  /**
+   * Get the value of the WHO_AM_I register
+   *
+   * @returns WHO_AM_I value
+   */
+  uint8_t getWhoAmI();
+
+  /**
+   * Get X axis acceleration
+   *
+   * @returns X axis acceleration
+   */
+  float getAccX();
+
+  /**
+   * Get Y axis acceleration
+   *
+   * @returns Y axis acceleration
+   */
+  float getAccY();
+  
+  /**
+   *  Read an X,Y pair
+   */
+  void getAccXY(float &x, float &y);
+
+  /**
+   * Get Z axis acceleration
+   *
+   * @returns Z axis acceleration
+   */
+  float getAccZ();
+
+  /**
+   * Get XYZ axis acceleration
+   *
+   * @param res array where acceleration data will be stored
+   */
+  void getAccAllAxis(float * res);
+
+private:
+  I2C m_i2c;
+  int m_addr;
+  void readRegs(int addr, uint8_t * data, int len);
+  void writeRegs(uint8_t * data, int len);
+  int16_t getAccAxis(uint8_t addr);
+
+};
+
+#endif
--- a/USBJoystick.cpp	Fri Jul 11 03:26:11 2014 +0000
+++ b/USBJoystick.cpp	Wed Jul 16 23:33:12 2014 +0000
@@ -99,9 +99,9 @@
              LOGICAL_MINIMUM(1), 0x81,   // each value ranges -127...
              LOGICAL_MAXIMUM(1), 0x7f,   // ...to 127
              REPORT_SIZE(1), 0x08,       // 8 bits per report
-             REPORT_COUNT(1), 0x03,      // 3 reports
+             REPORT_COUNT(1), 0x03,      // 2 reports
              INPUT(1), 0x02,             // Data, Variable, Absolute
-        
+
              REPORT_COUNT(1), 0x08,      // input report count (LEDWiz messages)
              0x09, 0x01,                 // usage
              0x91, 0x01,                 // Output (array)
--- a/main.cpp	Fri Jul 11 03:26:11 2014 +0000
+++ b/main.cpp	Wed Jul 16 23:33:12 2014 +0000
@@ -1,31 +1,34 @@
 #include "mbed.h"
 #include "USBJoystick.h"
 #include "MMA8451Q.h"
-#include "tls1410r.h"
+#include "tsl1410r.h"
+#include "FreescaleIAP.h"
 
+// on-board RGB LED elements - we use these for diagnostics
 PwmOut led1(LED1), led2(LED2), led3(LED3);
-DigitalOut out1(PTE29);
 
-
+// calibration button - switch input and LED output
+DigitalIn calBtn(PTE29);
+DigitalOut calBtnLed(PTE23);
 
 static int pbaIdx = 0;
 
 // on/off state for each LedWiz output
-static uint8_t ledOn[32];
+static uint8_t wizOn[32];
 
 // profile (brightness/blink) state for each LedWiz output
-static uint8_t ledVal[32] = {
+static uint8_t wizVal[32] = {
     0, 0, 0, 0, 0, 0, 0, 0,
     0, 0, 0, 0, 0, 0, 0, 0,
     0, 0, 0, 0, 0, 0, 0, 0,
     0, 0, 0, 0, 0, 0, 0, 0
 };
 
-static double ledState(int idx)
+static float wizState(int idx)
 {
-    if (ledOn[idx]) {
+    if (wizOn[idx]) {
         // on - map profile brightness state to PWM level
-        uint8_t val = ledVal[idx];
+        uint8_t val = wizVal[idx];
         if (val >= 1 && val <= 48)
             return 1.0 - val/48.0;
         else if (val >= 129 && val <= 132)
@@ -39,27 +42,75 @@
     }
 }
 
-static void updateLeds()
+static void updateWizOuts()
+{
+    led1 = wizState(0);
+    led2 = wizState(1);
+    led3 = wizState(2);
+}
+
+struct AccPrv
 {
-    led1 = ledState(0);
-    led2 = ledState(1);
-    led3 = ledState(2);
-}
+    AccPrv() : x(0), y(0) { }
+    float x;
+    float y;
+    
+    double dist(AccPrv &b)
+    {
+        float dx = x - b.x, dy = y - b.y;
+        return sqrt(dx*dx + dy*dy);
+    }
+};
 
 int main(void)
 {
+    // turn off our on-board indicator LED
     led1 = 1;
     led2 = 1;
     led3 = 1;
-    Timer timer;
+    
+    // plunger calibration data
+    const int npix = 320;
+    int plungerMin = 0, plungerMax = npix;
+    
+    // plunger calibration button debounce timer
+    Timer calBtnTimer;
+    calBtnTimer.start();
+    int calBtnDownTime = 0;
+    int calBtnLit = false;
+    
+    // Calibration button state:
+    //  0 = not pushed
+    //  1 = pushed, not yet debounced
+    //  2 = pushed, debounced, waiting for hold time
+    //  3 = pushed, hold time completed - in calibration mode
+    int calBtnState = 0;
+    
+    // set up a timer for our heartbeat indicator
+    Timer hbTimer;
+    hbTimer.start();
+    int t0Hb = hbTimer.read_ms();
+    int hb = 0;
+    
+    // set a timer for accelerometer auto-centering
+    Timer acTimer;
+    acTimer.start();
+    int t0ac = acTimer.read_ms();
+    
+    // set up a timer for reading the plunger sensor
+    Timer ccdTimer;
+    ccdTimer.start();
+    int t0ccd = ccdTimer.read_ms();
+    
+#if 0
+    // DEBUG
+    Timer ccdDbgTimer;
+    ccdDbgTimer.start();
+    int t0ccdDbg = ccdDbgTimer.read_ms();
+#endif
 
-    // set up a timer for spacing USB reports   
-    timer.start();
-    float t0 = timer.read_ms();    
-    float tout1 = timer.read_ms();
-
-    // Create the joystick USB client.  Show a read LED while connecting, and
-    // change to green when connected.
+    // Create the joystick USB client.  Light the on-board indicator LED
+    // red while connecting, and change to green after we connect.
     led1 = 0.75;
     USBJoystick js(0xFAFA, 0x00F7, 0x0001);
     led1 = 1;
@@ -68,13 +119,23 @@
     // create the accelerometer object
     const int MMA8451_I2C_ADDRESS = (0x1d<<1);
     MMA8451Q accel(PTE25, PTE24, MMA8451_I2C_ADDRESS);
-    printf("MMA8451 ID: %d\r\n", accel.getWhoAmI());
     
     // create the CCD array object
-    TLS1410R ccd(PTE20, PTE21, PTB0);
+    TSL1410R ccd(PTE20, PTE21, PTB0);
+
+    // recent accelerometer readings, for auto centering
+    int iAccPrv = 0, nAccPrv = 0;
+    const int maxAccPrv = 5;
+    AccPrv accPrv[maxAccPrv];
 
-    // process sensor reports and LedWiz requests forever
-    int x = 0, y = 127, z = 0;
+    // last accelerometer report, in mouse coordinates
+    int x = 127, y = 127, z = 0;
+    
+    // raw accelerator centerpoint, on the unit interval (-1.0 .. +1.0)
+    float xCenter = 0.0, yCenter = 0.0;    
+
+    // we're all set up - now just loop, processing sensor reports and 
+    // host requests
     for (;;)
     {
         // Look for an incoming report.  Continue processing input as
@@ -85,7 +146,8 @@
         while (js.readNB(&report) && report.length == 8)
         {
             uint8_t *data = report.data;
-            if (data[0] == 64) {
+            if (data[0] == 64) 
+            {
                 // LWZ-SBA - first four bytes are bit-packed on/off flags
                 // for the outputs; 5th byte is the pulse speed (0-7)
                 //printf("LWZ-SBA %02x %02x %02x %02x ; %02x\r\n",
@@ -98,16 +160,17 @@
                         bit = 1;
                         ++ri;
                     }
-                    ledOn[i] = ((data[ri] & bit) != 0);
+                    wizOn[i] = ((data[ri] & bit) != 0);
                 }
     
-                // update the physical LED state
-                updateLeds();
+                // update the physical outputs
+                updateWizOuts();
                 
                 // reset the PBA counter
                 pbaIdx = 0;
             }
-            else {
+            else 
+            {
                 // LWZ-PBA - full state dump; each byte is one output
                 // in the current bank.  pbaIdx keeps track of the bank;
                 // this is incremented implicitly by each PBA message.
@@ -116,73 +179,242 @@
 
                 // update all output profile settings
                 for (int i = 0 ; i < 8 ; ++i)
-                    ledVal[pbaIdx + i] = data[i];
+                    wizVal[pbaIdx + i] = data[i];
 
                 // update the physical LED state if this is the last bank                    
                 if (pbaIdx == 24)
-                    updateLeds();
+                    updateWizOuts();
 
                 // advance to the next bank
                 pbaIdx = (pbaIdx + 8) & 31;
             }
         }
-        
-#if 1
-        // check the accelerometer
+       
+        // check for plunger calibration
+        if (!calBtn)
         {
-            // read the accelerometer
-            float xa = accel.getAccX();
-            float ya = accel.getAccY();
-            
-            // figure the new joystick position
-            int xnew = (int)(127 * xa);
-            int ynew = (int)(127 * ya);
-            
-            // send an update if the position has changed
-            if (xnew != x || ynew != y)
+            // check the state
+            switch (calBtnState)
             {
-                x = xnew;
-                y = ynew;
-
-                // send the status report
-                js.update(x, y, z, 0);
+            case 0: 
+                // button not yet pushed - start debouncing
+                calBtnTimer.reset();
+                calBtnDownTime = calBtnTimer.read_ms();
+                calBtnState = 1;
+                break;
+                
+            case 1:
+                // pushed, not yet debounced - if the debounce time has
+                // passed, start the hold period
+                if (calBtnTimer.read_ms() - calBtnDownTime > 50)
+                    calBtnState = 2;
+                break;
+                
+            case 2:
+                // in the hold period - if the button has been held down
+                // for the entire hold period, move to calibration mode
+                if (calBtnTimer.read_ms() - calBtnDownTime > 2050)
+                {
+                    // enter calibration mode
+                    calBtnState = 3;
+                    
+                    // reset the calibration limits
+                    plungerMax = 0;
+                    plungerMin = npix;
+                }
+                break;
             }
         }
-#else
-        // Send a joystick report if it's been long enough since the
-        // last report        
-        if (timer.read_ms() - t0 > 250)
+        else
+        {
+            // Button released.  If we're not already in calibration mode,
+            // reset the button state.  Once calibration mode starts, it sticks
+            // until the calibration time elapses.
+            if (calBtnState != 3)
+                calBtnState = 0;
+            else if (calBtnTimer.read_ms() - calBtnDownTime > 32500)
+                calBtnState = 0;
+        }       
+        
+        // light/flash the calibration button light, if applicable
+        int newCalBtnLit = calBtnLit;
+        switch (calBtnState)
         {
-            // send the current joystick status report
-            js.update(x, y, z, 0);
-
-            // update our internal joystick position record
-            x += dx;
-            y += dy;
-            z += dz;
-            if (x > xmax || x < xmin) {
-                dx = -dx;
-                x += 2*dx;
+        case 2:
+            // in the hold period - flash the light
+            newCalBtnLit = (((calBtnTimer.read_ms() - calBtnDownTime)/250) & 1);
+            break;
+            
+        case 3:
+            // calibration mode - show steady on
+            newCalBtnLit = true;
+            break;
+            
+        default:
+            // not calibrating/holding - show steady off
+            newCalBtnLit = false;
+            break;
+        }
+        if (calBtnLit != newCalBtnLit)
+        {
+            calBtnLit = newCalBtnLit;
+            calBtnLed = (calBtnLit ? 1 : 0);
+        }
+        
+        // read the plunger sensor
+        int znew = z;
+        /* if (ccdTimer.read_ms() - t0ccd > 33) */
+        {
+            // read the sensor at reduced resolution
+            uint16_t pix[npix];
+            ccd.read(pix, npix, 0);
+            
+#if 0
+            // debug - send samples every 5 seconds
+            if (ccdDbgTimer.read_ms() - t0ccdDbg > 5000)
+            {
+                for (int i = 0 ; i < npix ; ++i)
+                    printf("%x ", pix[i]);
+                printf("\r\n\r\n");
+            
+                ccdDbgTimer.reset();
+                t0ccdDbg = ccdDbgTimer.read_ms();
             }
-            if (y > ymax || y < ymin) {
-                dy = -dy;
-                y += 2*dy;
-            }
-            if (z > zmax || z < zmin) {
-                dz = -dz;
-                z += 2*dz;
-            }
+#endif
+    
+            // check which end is the brighter - this is the "tip" end
+            // of the plunger
+            long avg1 = (long(pix[0]) + long(pix[1]) + long(pix[2]) + long(pix[3]) + long(pix[4]))/5;
+            long avg2 = (long(pix[npix-1]) + long(pix[npix-2]) + long(pix[npix-3]) + long(pix[npix-4]) + long(pix[npix-5]))/5;
+            
+            // figure the midpoint in the brightness
+            long midpt = (avg1 + avg2)/2 * 3;
+            
+            // Work from the bright end to the dark end.  VP interprets the
+            // Z axis value as the amount the plunger is pulled: the minimum
+            // is the rest position, the maximum is fully pulled.  So we 
+            // essentially want to report how much of the sensor is lit,
+            // since this increases as the plunger is pulled back.
+            int si = 1, di = 1;
+            if (avg1 < avg2)
+                si = npix - 1, di = -1;
 
-            // note the time of the last report
-            t0 = timer.read_ms();
-        }            
-#endif
+            // scan for the midpoint                
+            for (int n = 1, i = si ; n < npix - 1 ; ++n, i += di)
+            {
+                // if we've crossed the midpoint, report this position
+                if (long(pix[i-1]) + long(pix[i]) + long(pix[i+1]) < midpt)
+                {
+                    // note the new position
+                    int pos = abs(i - si);
+                    
+                    // Calibrate, or apply calibration, depending on the mode.
+                    // In either case, normalize to a 0-127 range.  VP appears to
+                    // ignore negative Z axis values.
+                    if (calBtnState == 3)
+                    {
+                        // calibrating - note if we're expanding the calibration envelope
+                        if (pos < plungerMin)
+                            plungerMin = pos;   
+                        if (pos > plungerMax)
+                            plungerMax = pos;
+                            
+                        // normalize to the full physical range while calibrating
+                        znew = int(float(pos)/npix * 127);
+                    }
+                    else
+                    {
+                        // running normally - normalize to the calibration range
+                        if (pos < plungerMin)
+                            pos = plungerMin;
+                        if (pos > plungerMax)
+                            pos = plungerMax;
+                        znew = int(float(pos - plungerMin)/(plungerMax - plungerMin + 1) * 127);
+                    }
+                    
+                    // done
+                    break;
+                }
+            }
+            
+            // reset the timer
+            ccdTimer.reset();
+            t0ccd = ccdTimer.read_ms();
+        } 
+        
+        // read the accelerometer
+        float xa, ya;
+        accel.getAccXY(xa, ya);
+        
+        // check for auto-centering every so often
+        if (acTimer.read_ms() - t0ac > 1000) 
+        {
+            // add the sample to the history list
+            accPrv[iAccPrv].x = xa;
+            accPrv[iAccPrv].y = ya;
+            
+            // store the slot
+            iAccPrv += 1;
+            iAccPrv %= maxAccPrv;
+            nAccPrv += 1;
+            
+            // If we have a full complement, check for stability.  The
+            // raw accelerometer input is in the rnage -4096 to 4096, but
+            // the class cover normalizes to a unit interval (-1.0 .. +1.0).
+            const float accTol = .005;
+            if (nAccPrv >= maxAccPrv
+                && accPrv[0].dist(accPrv[1]) < accTol
+                && accPrv[0].dist(accPrv[2]) < accTol
+                && accPrv[0].dist(accPrv[3]) < accTol
+                && accPrv[0].dist(accPrv[4]) < accTol)
+            {
+                // figure the new center
+                xCenter = (accPrv[0].x + accPrv[1].x + accPrv[2].x + accPrv[3].x + accPrv[4].x)/5.0;
+                yCenter = (accPrv[0].y + accPrv[1].y + accPrv[2].y + accPrv[3].y + accPrv[4].y)/5.0;
+            }
+            
+            // reset the auto-center timer
+            acTimer.reset();
+            t0ac = acTimer.read_ms();
+        }
+        
+        // adjust for our auto centering
+        xa -= xCenter;
+        ya -= yCenter;
+        
+        // confine to the unit interval
+        if (xa < -1.0) xa = -1.0;
+        if (xa > 1.0) xa = 1.0;
+        if (ya < -1.0) ya = -1.0;
+        if (ya > 1.0) ya = 1.0;
 
-        // pulse E29
-        if (timer.read_ms() - tout1 > 2000)
+        // figure the new mouse report data
+        int xnew = (int)(127 * xa);
+        int ynew = (int)(127 * ya);
+        
+        // send an update if the position has changed
+        // if (xnew != x || ynew != y || znew != z)
         {
-            out1 = !out1;
-            tout1 = timer.read_ms();
+            x = xnew;
+            y = ynew;
+            z = znew;
+
+            // Send the status report.  Note that the X axis needs to be
+            // reversed, becasue the native accelerometer reports seem to
+            // assume that the card is component side down.
+            js.update(x, -y, z, 0);
         }
-    }    
+        
+        // show a heartbeat flash in blue every so often
+        if (hbTimer.read_ms() - t0Hb > 1000) 
+        {
+            // invert the blue LED state
+            hb = !hb;
+            led3 = (hb ? .5 : 1);
+            
+            // reset the heartbeat timer
+            hbTimer.reset();
+            t0Hb = hbTimer.read_ms();
+        }
+    }
 }
--- a/tls1410r.cpp	Fri Jul 11 03:26:11 2014 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,74 +0,0 @@
-#include "mbed.h"
-#include "tls1410r.h"
-
-TLS1410R::TLS1410R(PinName siPort, PinName clockPort, PinName aoPort)
-    : si(siPort), clock(clockPort), ao(aoPort)
-{
-    // clear out power-on noise by clocking through all pixels twice
-    clear();
-    clear();
-}
-
-void TLS1410R::clear()
-{
-    // clock in an SI pulse
-    si = 1;
-    clock = 1;
-    clock = 0;
-    si = 0;
-    
-    // clock out all pixels
-    for (int i = 0 ; i < nPix+1 ; ++i) {
-        clock = 1;
-        clock = 0;
-    }
-}
-
-void TLS1410R::read(uint16_t *pix, int n, int integrate_us)
-{
-    // Start an integration cycle - pulse SI, then clock all pixels.  The
-    // CCD will integrate light starting 18 clocks after the SI pulse, and
-    // continues integrating until the next SI pulse, which cannot occur
-    // until all pixels have been clocked.
-    si = 1;
-    clock = 1;
-    clock = 0;
-    si = 0;
-    for (int i = 0 ; i < nPix+1 ; ++i) {
-        clock = 1;
-        clock = 0;
-    }
-        
-    // delay by the specified additional integration time
-    wait_us(integrate_us);
-    
-    // end the current integration cycle and hold the integrated values
-    si = 1;
-    clock = 1;
-    clock = 0;
-    si = 0;
-    
-    // figure how many pixels to skip on each read
-    int skip = nPix/n - 1;
-
-    // read the pixels
-    for (int src = 0, dst = 0 ; src < nPix ; ++src)
-    {
-        // read this pixel
-        pix[dst++] = ao;
-        
-        // clock in the next pixel
-        clock = 1;
-        clock = 0;
-        
-        // clock skipped pixels
-        for (int i = 0 ; i < skip ; ++i) {
-            clock = 1;
-            clock = 0;
-        }
-    }
-    
-    // clock out one extra pixel to make sure the device is ready for another go
-    clock = 1;
-    clock = 0;
-}
--- a/tls1410r.h	Fri Jul 11 03:26:11 2014 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,41 +0,0 @@
-/*
- *  TLS1410R interface class.
- *
- *  This provides a high-level interface for the Taos TLS1410R linear CCD array sensor.
- */
- 
- #include "mbed.h"
- 
- #ifndef TLS1410R_H
- #define TLS1410R_H
- 
-class TLS1410R
-{
-public:
-    // set up with the two DigitalOut ports (SI and clock), and the
-    // analog in port for reading the currently selected pixel value
-    TLS1410R(PinName siPort, PinName clockPort, PinName aoPort);
-
-    // Integrate light and read the pixels.  Fills in pix[] with the pixel values,
-    // scaled 0-0xffff.  n is the number of pixels to read; if this is less than
-    // the total number of pixels npix, we'll read every mth pixel, where m = npix/n.
-    // E.g., if you want 640 pixels out of 1280 on the sensor, we'll read every
-    // other pixel.  If you want 320, we'll read every fourth pixel.
-    // Before reading, we'll pause for integrate_us additional microseconds during
-    // the integration phase; use 0 for no additional integration time. 
-    void read(uint16_t *pix, int n, int integrate_us);
-
-    // clock through all pixels to clear the array
-    void clear();
-
-    // number of pixels in the array
-    static const int nPix = 1280;
-    
-    
-private:
-    DigitalOut si;
-    DigitalOut clock;
-    AnalogIn ao;
-};
- 
-#endif /* TLS1410R_H */
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tsl1410r.h	Wed Jul 16 23:33:12 2014 +0000
@@ -0,0 +1,41 @@
+/*
+ *  TSL1410R interface class.
+ *
+ *  This provides a high-level interface for the Taos TSL1410R linear CCD array sensor.
+ */
+ 
+ #include "mbed.h"
+ 
+ #ifndef TSL1410R_H
+ #define TSL1410R_H
+ 
+class TSL1410R
+{
+public:
+    // set up with the two DigitalOut ports (SI and clock), and the
+    // analog in port for reading the currently selected pixel value
+    TSL1410R(PinName siPort, PinName clockPort, PinName aoPort);
+
+    // Integrate light and read the pixels.  Fills in pix[] with the pixel values,
+    // scaled 0-0xffff.  n is the number of pixels to read; if this is less than
+    // the total number of pixels npix, we'll read every mth pixel, where m = npix/n.
+    // E.g., if you want 640 pixels out of 1280 on the sensor, we'll read every
+    // other pixel.  If you want 320, we'll read every fourth pixel.
+    // Before reading, we'll pause for integrate_us additional microseconds during
+    // the integration phase; use 0 for no additional integration time. 
+    void read(uint16_t *pix, int n, int integrate_us);
+
+    // clock through all pixels to clear the array
+    void clear();
+
+    // number of pixels in the array
+    static const int nPix = 1280;
+    
+    
+private:
+    DigitalOut si;
+    DigitalOut clock;
+    AnalogIn ao;
+};
+ 
+#endif /* TSL1410R_H */
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tsl410r.cpp	Wed Jul 16 23:33:12 2014 +0000
@@ -0,0 +1,74 @@
+#include "mbed.h"
+#include "tsl1410r.h"
+
+TSL1410R::TSL1410R(PinName siPort, PinName clockPort, PinName aoPort)
+    : si(siPort), clock(clockPort), ao(aoPort)
+{
+    // clear out power-on noise by clocking through all pixels twice
+    clear();
+    clear();
+}
+
+void TSL1410R::clear()
+{
+    // clock in an SI pulse
+    si = 1;
+    clock = 1;
+    clock = 0;
+    si = 0;
+    
+    // clock out all pixels
+    for (int i = 0 ; i < nPix+1 ; ++i) {
+        clock = 1;
+        clock = 0;
+    }
+}
+
+void TSL1410R::read(uint16_t *pix, int n, int integrate_us)
+{
+    // Start an integration cycle - pulse SI, then clock all pixels.  The
+    // CCD will integrate light starting 18 clocks after the SI pulse, and
+    // continues integrating until the next SI pulse, which cannot occur
+    // until all pixels have been clocked.
+    si = 1;
+    clock = 1;
+    clock = 0;
+    si = 0;
+    for (int i = 0 ; i < nPix+1 ; ++i) {
+        clock = 1;
+        clock = 0;
+    }
+        
+    // delay by the specified additional integration time
+    wait_us(integrate_us);
+    
+    // end the current integration cycle and hold the integrated values
+    si = 1;
+    clock = 1;
+    clock = 0;
+    si = 0;
+    
+    // figure how many pixels to skip on each read
+    int skip = nPix/n - 1;
+
+    // read the pixels
+    for (int src = 0, dst = 0 ; src < nPix ; ++src)
+    {
+        // read this pixel
+        pix[dst++] = ao.read_u16();
+        
+        // clock in the next pixel
+        clock = 1;
+        clock = 0;
+        
+        // clock skipped pixels
+        for (int i = 0 ; i < skip ; ++i, ++src) {
+            clock = 1;
+            clock = 0;
+        }
+    }
+    
+    // clock out one extra pixel to make sure the device is ready for another go
+    clock = 1;
+    clock = 0;
+}