= Pimp My Sumovore =

|| After Nick Jones' original work with the Sumovore, and Simons subsequent experiments, I decided it was time to start pulling somthing together a bit. This was also inspired by Linton Village College starting up an Afterschool robotics club, for which we suggested the Sumovore as a great platform to build on.|| [[Image(source:/PimpMySumovore/doc/sumovore.jpg, title="Sumovore", 50%, nolink)]]  ||

The plan is to build a prototyping PCB platform that links the Sumovore sensors and motor drivers to the mbed board to take care of the wiring and form factor, but allow for experimentation.

== The connections ==

The first thing to look at is the connectivity between the main Sumovore board, and the brain board. I have taken the table of conenctions from Simons page, and reassigned the wire to more suitable positions.

||mbed pin||Sumovore pin||Explanation||
||GND||Pin 1||Ground||
||VIN||Pin 2||mbed input voltage||
||5||Pin 3||Left reverse enable||
||6||Pin 4||Left forward enable||
||7||Pin 5||Right reverse enable||
||8||Pin 6||Right forward enable||
||23||Pin 7||Left PWM||
||24||Pin 8||Right PWM||
||29||Pin 9||IR DET1||
||30||Pin 10||IR DET2||
||20||Pin 17||Edge1 Detector||
||19||Pin 18||Edge2 Detector||
||17||Pin 20||Edge3 Detector||
||16||Pin 19||Edge4 Detector||
||15||Pin 21||Edge5 Detector||


== The PCB ==

The main requirements are :

  * To be a drop in replacement for the Sumovore "Discrete brain board"
  * Replace the IR detector threshold detectors with a fixed resistor circuit connected to an AnalogIn - let the software decide, not a pot!
  * To hook up to tall the sensors and motor controllers, leaving as much useful IO free as possible.
  * Provide a PCB prototyping space for adding additional circuits
  * Provide easy access to all the mbed pins
  * Provide easy access to 0v, 3v3 and 5v

The PCB was captured and layed out in Eagle, and I had 20-off manufactured at PCBCART.com, costing a total of $150.

When it is up and running, I'll post the gerbers, in the mean time, here are the:

   * [source:/PimpMySumovore/doc/SumovoreBrainboard_sch.pdf Schematics]   
   * [source:/PimpMySumovore/doc/SumovoreBrainboard_pcb.pdf Layout]   
   * [source:/PimpMySumovore/doc/SumovoreBrainboard.png Screenshot]   


== Building it up ==

Okay, so it is 12:05 on 24/11/2008, and I have just got an email from reception to tell me my PCBs have arrived. I hit F5 in IE which has been open at the FedEx tracking page since 6am, and FedEx also tell me my PCBs are here.

The first thing I noticed is that although I ordered the longest possible pin connectors from Farnell, the ones I were after are now end-of-line and were replaced with something a little shorter, unfortunatley a little too short. So i'm onthe hunt again for SIL pin headers of the right length. In the mean time, I only push the pins through the PCB just enough to be able to soder them, keeping as much as I can below.

I have now ordered some parts from SAMTEC. Part number MTSW-108-11-T-S-600. I got them all 8 way, as there are 2 x 8 way connectors, and 2 x 4 way. three per board, snapping one in half for the 4 ways.

I've used a pair of 20 way SIL sockets for mounting the mbed board. They do make the mbed board sit very tall, but thats not too much of a problem.

I measureed the resistance that has been set on the potentiometer for the IR detectors to be 340k, which is consistent with being about 1/6 of a turn of the 2M pot. As I didnt have 330k resistors o hand, I've used some 390k. I will eventually get some 330k resistors and swap them in so I have a good reference point when it comes to useing the AnalogIn for sensing.


== First program ==

The first thing to do is take Simons original code, and port it to the new connectivity.


{{{
#include "mbed.h"

DigitalOut leftrev(p5);
DigitalOut leftfwd(p6);
DigitalOut rightrev(p7);
DigitalOut rightfwd(p8);

PwmOut pwmleft(p23);
PwmOut pwmright(p24);

int main() {
	leftfwd = 1;
	leftrev = 0;
	rightfwd = 1;
	rightrev = 0;

	pwmleft = 1;
	pwmright = 1;
	
	wait(1);

	leftfwd = 0;
	leftrev = 0;
	rightfwd = 0;
	rightrev = 0;	
}
}}}

Yup, as with Simons attempts, this got it moving.


== Motor Abstraction ==

As with Simons experiments, the next experiment is to make a Motor abstraction to simplify the control:

{{{
#include "mbed.h"

class Motor {
public:
	Motor(int pwm, int fwd, int rev) : _pwm(pwm), _fwd(fwd), _rev(rev) {}
	
	void speed(float p) {
		_fwd = (p > 0.0);
		_rev = (p < 0.0);
		_pwm = abs(p);
	}
	
private:
	PwmOut _pwm;
	DigitalOut _fwd;
	DigitalOut _rev;
};

Motor left(p23, p6, p5);
Motor right(p24, p8, p7);

int main() {
	left.speed(1);
	right.speed(1);
	
	wait(1);

	left.speed(0);
	right.speed(0);
}
}}}

Note this does exactly the same as before, but now the raw pwm and digitial motor controls are abstracted to a Motor object with a single speed control which takes a percentage between -1.0 and 1.0.

== Logo style interpreter ==

Now there is a nice abstraction for the motors, the next step is to reuse Nick Jones' code to recreate the logo style interpreter.

The code can be imported as a project :

   * [http://mbed.org/users/chris/published/f1cb7d1ecfd8aeeb36a8dce114f6a49a/mbedsumovore_logo.zip mbedsumovore_logo]

{{{
#include "mbed.h"
#include "Motor.h"

/*
 *  This code reads command files to control the motors.
 *  The file name it reads is command.txt
 *
 *  The file format is :
 *
 *      <command> <data> 
 *
 *  The commands are :
 *
 *      F - Forward, both motor on full speed forwards
 *      B - Backwards, both motors on full speed in reverse
 *      L - Left, left motor full speed backwards, right motor full speed forward
 *      R - Right, right motor full speed backwards, left motor full speed forward
 *      W - Wait, both motors stop
 *
 *  Data :
 *
 *      Data is a time in milliseconds to carry out the command.
 *
 *  Example :
 *
 *      F 1000
 *      W 200
 *      L 1000
 *      W 200
 *      R 1000
 *      W 200
 *      B 1000
 *      W 200
 */


LocalFileSystem local("local");

Serial pc(USBTX, USBRX);

BusOut leds(LED1,LED2,LED3,LED4);

Motor left(p23, p6, p5);
Motor right(p24, p8, p7);


int main() {    
            
    leds = 0x0;
    
    // flash the LED 3 time before starting
    for (int i=0; i < 3 ; i++) {
        leds = 0x1;    
        wait (0.5);    
        leds = 0x0;    
        wait (0.5);
    }
        
    // Open the command.txt file
    FILE *commandfile = fopen("/local/command.txt", "r");

    // If there is no file, sit flashing the LEDs
    if (commandfile == NULL) { 
        while(1) {
            leds = 0xf;
            wait(0.5);
            leds = 0x0;
            wait(0.5);
        }
    } 
    
    // process each of the commands in the file
    while (!feof(commandfile)) {
    
        char command = 0;
        int data = 0.0;
         
        // Read from the command file
        fscanf(commandfile, "%c %d\n", &command, &data); 
                         
        if((command=='f') || (command=='F')){
                left.speed(1);
                right.speed(1);
        }        
        else if((command=='b') || (command=='B')){
                left.speed(-1);
                right.speed(-1);
        }
        else if((command=='l') || (command=='L')){
                left.speed(-1);
                right.speed(1);
        }
        else if ((command=='r') || (command=='R')){
                left.speed(1);
                right.speed(-1);
        }
        // Wait commands
        else if ((command=='w') || (command=='W')){
        }

        // wait for the length of the command
        wait(data/1000.0);        

        // Switch the motors off
        left.speed(0);
        right.speed(0);


    } // this is the end of the file while loop


    for (int i=0;i<10;i++) {
        leds = 0x0;
        wait (0.2);
        leds = 0xf;
        wait (0.2);
    }
        
    fclose(commandfile);
    exit(0);
    
} // end of main
}}}