HM Yoong
Dependents: BMS_BMUCore_Max_DummyData
Revision 0:245af9360f0d, committed 2012-02-28
- Comitter:
- yoonghm
- Date:
- Tue Feb 28 07:42:07 2012 +0000
- Commit message:
Changed in this revision
| DS1820.cpp | Show annotated file Show diff for this revision Revisions of this file |
| DS1820.h | Show annotated file Show diff for this revision Revisions of this file |
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/DS1820.cpp Tue Feb 28 07:42:07 2012 +0000
@@ -0,0 +1,357 @@
+#include "DS1820.h"
+#include "mbed.h"
+
+// Global variables shared between all DS1820 objects
+bool DS1820_done_flag;
+int DS1820_last_descrepancy;
+char DS1820_search_ROM[8];
+
+
+DS1820::DS1820 (PinName data_pin, PinName power_pin) : _datapin(data_pin), _parasitepin(power_pin) {
+ int byte_counter;
+ _parasite_power = true;
+ for(byte_counter=0;byte_counter<8;byte_counter++)
+ ROM[byte_counter] = 0xFF;
+ for(byte_counter=0;byte_counter<9;byte_counter++)
+ RAM[byte_counter] = 0x00;
+}
+DS1820::DS1820 (PinName data_pin) : _datapin(data_pin), _parasitepin(NC) {
+ int byte_counter;
+ _parasite_power = false;
+ for(byte_counter=0;byte_counter<8;byte_counter++)
+ ROM[byte_counter] = 0xFF;
+ for(byte_counter=0;byte_counter<9;byte_counter++)
+ RAM[byte_counter] = 0x00;
+}
+
+bool DS1820::onewire_reset() {
+// This will return false if no devices are present on the data bus
+ bool presence=false;
+ _datapin.output();
+ _datapin = 0; // bring low for 500 us
+ wait_us(500);
+ _datapin.input(); // let the data line float high
+ wait_us(90); // wait 90us
+ if (_datapin.read()==0) // see if any devices are pulling the data line low
+ presence=true;
+ wait_us(410);
+ return presence;
+}
+
+void DS1820::onewire_bit_out (bool bit_data) {
+ _datapin.output();
+ _datapin = 0;
+ wait_us(5);
+ if (bit_data) {
+ _datapin.input(); // bring data line high
+ wait_us(55);
+ } else {
+ wait_us(55); // keep data line low
+ _datapin.input();
+ }
+}
+
+void DS1820::onewire_byte_out(char data) { // output data character (least sig bit first).
+ int n;
+ for (n=0; n<8; n++) {
+ onewire_bit_out(data & 0x01);
+ data = data >> 1; // now the next bit is in the least sig bit position.
+ }
+}
+
+bool DS1820::onewire_bit_in() {
+ bool answer;
+ _datapin.output();
+ _datapin = 0;
+ wait_us(5);
+ _datapin.input();
+ wait_us(5);
+ answer = _datapin.read();
+ wait_us(50);
+ return answer;
+}
+
+char DS1820::onewire_byte_in() { // read byte, least sig byte first
+ char answer = 0x00;
+ int i;
+ for (i=0; i<8; i++) {
+ answer = answer >> 1; // shift over to make room for the next bit
+ if (onewire_bit_in())
+ answer = answer | 0x80; // if the data port is high, make this bit a 1
+ }
+ return answer;
+}
+
+bool DS1820::search_ROM() {
+ return search_ROM_routine(0xF0); // Search ROM command
+}
+
+bool DS1820::search_alarm() {
+ return search_ROM_routine(0xEC); // Search Alarm command
+}
+
+bool DS1820::search_ROM_routine(char command) {
+ extern bool DS1820_done_flag;
+ extern int DS1820_last_descrepancy;
+ extern char DS1820_search_ROM[8];
+ int descrepancy_marker, ROM_bit_index;
+ bool return_value, Bit_A, Bit_B;
+ char byte_counter, bit_mask;
+
+ return_value=false;
+ if (!DS1820_done_flag) {
+ if (!onewire_reset()) {
+ DS1820_last_descrepancy = 0; // no devices present
+ } else {
+ ROM_bit_index=1;
+ descrepancy_marker=0;
+ onewire_byte_out(command); // Search ROM command or Search Alarm command
+ byte_counter = 0;
+ bit_mask = 0x01;
+ while (ROM_bit_index<=64) {
+ Bit_A = onewire_bit_in();
+ Bit_B = onewire_bit_in();
+ if (Bit_A & Bit_B) {
+ descrepancy_marker = 0; // data read error, this should never happen
+ ROM_bit_index = 0xFF;
+ } else {
+ if (Bit_A | Bit_B) {
+ // Set ROM bit to Bit_A
+ if (Bit_A) {
+ DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] | bit_mask; // Set ROM bit to one
+ } else {
+ DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] & ~bit_mask; // Set ROM bit to zero
+ }
+ } else {
+ // both bits A and B are low, so there are two or more devices present
+ if ( ROM_bit_index == DS1820_last_descrepancy ) {
+ DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] | bit_mask; // Set ROM bit to one
+ } else {
+ if ( ROM_bit_index > DS1820_last_descrepancy ) {
+ DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] & ~bit_mask; // Set ROM bit to zero
+ descrepancy_marker = ROM_bit_index;
+ } else {
+ if (( DS1820_search_ROM[byte_counter] & bit_mask) == 0x00 )
+ descrepancy_marker = ROM_bit_index;
+ }
+ }
+ }
+ onewire_bit_out (DS1820_search_ROM[byte_counter] & bit_mask);
+ ROM_bit_index++;
+ if (bit_mask & 0x80) {
+ byte_counter++;
+ bit_mask = 0x01;
+ } else {
+ bit_mask = bit_mask << 1;
+ }
+ }
+ }
+ DS1820_last_descrepancy = descrepancy_marker;
+ if (ROM_bit_index != 0xFF) {
+ for(byte_counter=0;byte_counter<8;byte_counter++)
+ ROM[byte_counter] = DS1820_search_ROM[byte_counter];
+ return_value = true;
+ }
+ }
+ if (DS1820_last_descrepancy == 0)
+ DS1820_done_flag = true;
+ }
+ return return_value;
+}
+
+void DS1820::search_ROM_setup() {
+ extern bool DS1820_done_flag;
+ extern int DS1820_last_descrepancy;
+ extern char DS1820_search_ROM[8];
+ DS1820_done_flag = false;
+ DS1820_last_descrepancy = 0;
+ int i;
+ for (i=0; i<8; i++)
+ DS1820_search_ROM[i]=0x00;
+}
+
+void DS1820::read_ROM() {
+ // NOTE: This command can only be used when there is one DS1820 on the bus. If this command
+ // is used when there is more than one slave present on the bus, a data collision will occur
+ // when all the DS1820s attempt to respond at the same time.
+ int i;
+ onewire_reset();
+ onewire_byte_out(0x33); // Read ROM id
+ for (i=0; i<8; i++)
+ ROM[i]=onewire_byte_in();
+}
+
+void DS1820::match_ROM() {
+// Used to select a specific device
+ int i;
+ onewire_reset();
+ onewire_byte_out( 0x55); //Match ROM command
+ for (i=0;i<8;i++)
+ onewire_byte_out(ROM[i]);
+}
+
+void DS1820::skip_ROM() {
+ onewire_reset();
+ onewire_byte_out(0xCC); // Skip ROM command
+}
+
+bool DS1820::ROM_checksum_error() {
+ char CRC=0x00;
+ int i;
+ for(i=0;i<7;i++) // Only going to shift the lower 7 bytes
+ CRC = CRC_byte(CRC, ROM[i]);
+ // After 7 bytes CRC should equal the 8th byte (ROM CRC)
+ return (CRC!=ROM[7]); // will return true if there is a CRC checksum error
+}
+
+bool DS1820::RAM_checksum_error() {
+ char CRC=0x00;
+ int i;
+ read_RAM();
+ for(i=0;i<8;i++) // Only going to shift the lower 8 bytes
+ CRC = CRC_byte(CRC, RAM[i]);
+ // After 8 bytes CRC should equal the 9th byte (RAM CRC)
+ return (CRC!=RAM[8]); // will return true if there is a CRC checksum error
+}
+
+char DS1820::CRC_byte (char CRC, char byte ) {
+ int j;
+ for(j=0;j<8;j++) {
+ if ((byte & 0x01 ) ^ (CRC & 0x01)) {
+ // DATA ^ LSB CRC = 1
+ CRC = CRC>>1;
+ // Set the MSB to 1
+ CRC = CRC | 0x80;
+ // Check bit 3
+ if (CRC & 0x04) {
+ CRC = CRC & 0xFB; // Bit 3 is set, so clear it
+ } else {
+ CRC = CRC | 0x04; // Bit 3 is clear, so set it
+ }
+ // Check bit 4
+ if (CRC & 0x08) {
+ CRC = CRC & 0xF7; // Bit 4 is set, so clear it
+ } else {
+ CRC = CRC | 0x08; // Bit 4 is clear, so set it
+ }
+ } else {
+ // DATA ^ LSB CRC = 0
+ CRC = CRC>>1;
+ // clear MSB
+ CRC = CRC & 0x7F;
+ // No need to check bits, with DATA ^ LSB CRC = 0, they will remain unchanged
+ }
+ byte = byte>>1;
+ }
+return CRC;
+}
+
+void DS1820::convert_temperature(devices device) {
+ // Convert temperature into scratchpad RAM for all devices at once
+ if (device==all_devices)
+ skip_ROM(); // Skip ROM command, will convert for ALL devices
+ else
+ match_ROM();
+ onewire_byte_out( 0x44); // perform temperature conversion
+ if (_parasite_power)
+ _parasitepin = 1; // Parasite power strong pullup
+ wait_ms(750);
+ if (_parasite_power)
+ _parasitepin = 0;
+}
+
+void DS1820::read_RAM() {
+ // This will copy the DS1820's 9 bytes of RAM data
+ // into the objects RAM array. Functions that use
+ // RAM values will automaticly call this procedure.
+ int i;
+ match_ROM(); // Select this device
+ onewire_byte_out( 0xBE); //Read Scratchpad command
+ for(i=0;i<9;i++) {
+ RAM[i] = onewire_byte_in();
+ }
+}
+
+int DS1820::read_scratchpad() {
+ int answer;
+ read_RAM();
+ answer = (RAM[2]<<8) + RAM[3];
+ return answer;
+}
+
+void DS1820::write_scratchpad(int data) {
+ RAM[3] = data;
+ RAM[2] = data>>8;
+ match_ROM();
+ onewire_byte_out(0x4E); // Copy scratchpad into DS1820 ram memory
+ onewire_byte_out(RAM[2]); // T(H)
+ onewire_byte_out(RAM[3]); // T(L)
+}
+
+void DS1820::store_scratchpad(devices device) {
+ if (device==all_devices)
+ skip_ROM(); // Skip ROM command, will store for ALL devices
+ else
+ match_ROM();
+ onewire_byte_out(0x48); // Write scratchpad into E2 command
+ if (_parasite_power)
+ _parasitepin=1;
+ wait_ms(10); // Parasite power strong pullup for 10ms
+ if (_parasite_power)
+ _parasitepin=0;
+}
+
+int DS1820::recall_scratchpad(devices device) {
+// This copies the E2 values into the DS1820's memory.
+// If you specify all_devices this will return zero, otherwise
+// it will return the value of the scratchpad memory.
+ int answer=0;
+ if (device==all_devices)
+ skip_ROM(); // Skip ROM command, will recall for ALL devices
+ else
+ match_ROM();
+ onewire_byte_out(0xB8); // Recall E2 data to scratchpad command
+ wait_ms(10); // not sure I like polling for completion
+ // it could cause an infinite loop
+ if (device==DS1820::this_device) {
+ read_RAM();
+ answer = read_scratchpad();
+ }
+ return answer;
+}
+
+float DS1820::temperature(char scale) {
+// The data specs state that count_per_degree should be 0x10 (16), I found my devices
+// to have a count_per_degree of 0x4B (75). With the standard resolution of 1/2 deg C
+// this allowed an expanded resolution of 1/150th of a deg C. I wouldn't rely on this
+// being super acurate, but it does allow for a smooth display in the 1/10ths of a
+// deg C or F scales.
+ float answer, remaining_count, count_per_degree;
+ int reading;
+ read_RAM();
+ reading = (RAM[1] << 8) + RAM[0];
+ if (reading & 0x8000) { // negative degrees C
+ reading = 0-((reading ^ 0xffff) + 1); // 2's comp then convert to signed int
+ }
+ remaining_count = RAM[6];
+ count_per_degree = RAM[7];
+ answer = reading +0.0;
+ answer = answer - 0.25 + (count_per_degree - remaining_count) / count_per_degree;
+ if (scale=='C' or scale=='c')
+ answer = answer / 2.0;
+ else
+ // Convert to deg F
+ answer = answer * 9.0 / 10.0 + 32.0;
+ return answer;
+}
+
+bool DS1820::read_power_supply(devices device) {
+// This will return true if the device (or all devices) are Vcc powered
+// This will return false if the device (or ANY device) is parasite powered
+ if (device==all_devices)
+ skip_ROM(); // Skip ROM command, will poll for any device using parasite power
+ else
+ match_ROM();
+ onewire_byte_out(0xB4); // Read power supply command
+ return onewire_bit_in();
+}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/DS1820.h Tue Feb 28 07:42:07 2012 +0000
@@ -0,0 +1,252 @@
+/* mbed DS1820 Library, for the Dallas (Maxim) 1-Wire Digital Thermometer
+ * Copyright (c) 2010, Michael Hagberg Michael@RedBoxCode.com
+ *
+ * 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 MBED_DS1820_H
+#define MBED_DS1820_H
+
+#include "mbed.h"
+
+// ****** THIS GLOBAL VARIABLES MUST BE DEFINED IN main.cpp
+
+// Global variables shared between all DS1820 objects
+//bool DS1820_done_flag;
+//int DS1820_last_descrepancy;
+//char DS1820_search_ROM[8];
+
+/** DS1820 Dallas 1-Wire Temperature Probe
+ *
+ * Example:
+ * @code
+ * #include "mbed.h"
+ *
+ * #include "TextLCD.h"
+ * #include "DS1820.h"
+ *
+ * TextLCD lcd(p25, p26, p21, p22, p23, p24, TextLCD::LCD16x2); // rs, e, d0-d3, layout
+ *
+ * const int MAX_PROBES = 16;
+ * DS1820* probe[MAX_PROBES];
+ *
+ * int main() {
+ * int i;
+ * int devices_found=0;
+ * // Initialize the probe array to DS1820 objects
+ * for (i = 0; i < MAX_PROBES; i++)
+ * probe[i] = new DS1820(p27);
+ * // Initialize global state variables
+ * probe[0]->search_ROM_setup();
+ * // Loop to find all devices on the data line
+ * while (probe[devices_found]->search_ROM() and devices_found<MAX_PROBES-1)
+ * devices_found++;
+ * // If maximum number of probes are found,
+ * // bump the counter to include the last array entry
+ * if (probe[devices_found]->ROM[0] != 0xFF)
+ * devices_found++;
+ *
+ * lcd.cls();
+ * if (devices_found==0)
+ * lcd.printf("No devices found");
+ * else {
+ * while (true) {
+ * probe[0]->convert_temperature(DS1820::all_devices);
+ * lcd.cls();
+ * for (i=0; i<devices_found; i++) {
+ * lcd.printf("%3.1f ",probe[i]->temperature('f'));
+ * }
+ * }
+ * }
+ * }
+ * @endcode
+ */
+
+class DS1820 {
+public:
+ enum devices{
+ this_device, // command applies to only this device
+ all_devices }; // command applies to all devices
+
+ /** Create a probe object connected to the specified pins
+ *
+ * @param data_pin DigitalInOut pin for the data bus
+ * @param power_pin DigitalOut pin to control the power MOSFET
+ */
+ DS1820(PinName data_pin, PinName power_pin); // Constructor with parasite power pin
+
+ /** Create a probe object connected to the specified pin
+ * this is used when all probes are externally powered
+ *
+ * @param data_pin DigitalInOut pin for the data bus
+ */
+ DS1820(PinName data_pin);
+
+ /** ROM is a copy of the internal DS1820's ROM
+ * It's created during the search_ROM() or search_alarm() commands
+ *
+ * ROM[0] is the Dallas Family Code
+ * ROM[1] thru ROM[6] is the 48-bit unique serial number
+ * ROM[7] is the device CRC
+ */
+ char ROM[8];
+
+ /** RAM is a copy of the internal DS1820's RAM
+ * It's updated during the read_RAM() command
+ * which is automaticaly called from any function
+ * using the RAM values.
+ */
+ char RAM[9];
+
+ /* This function copies the DS1820's RAM into the object's
+ * RAM[].
+ */
+ void read_RAM();
+
+ /** This routine initializes the global variables used in
+ * the search_ROM() and search_alarm() funtions. It should
+ * be called once before looping to find devices.
+ */
+ void search_ROM_setup();
+
+ /** This routine will search for an unidentified device
+ * on the bus. It uses the variables in search_ROM_setup
+ * to remember the pervious ROM address found.
+ * It will return FALSE if there were no new devices
+ * discovered on the bus.
+ */
+ bool search_ROM();
+
+ /** This routine will search for an unidentified device
+ * which has the temperature alarm bit set. It uses the
+ * variables in search_ROM_setup to remember the pervious
+ * ROM address found. It will return FALSE if there were
+ * no new devices with alarms discovered on the bus.
+ */
+ bool search_alarm();
+
+ /** This routine will read the ROM (Family code, serial number
+ * and Checksum) from a dedicated device on the bus.
+ *
+ * NOTE: This command can only be used when there is only one
+ * DS1820 on the bus. If this command is used when there
+ * is more than one slave present on the bus, a data
+ * collision will occur when all the DS1820s attempt to
+ * respond at the same time.
+ */
+ void read_ROM();
+
+ /** This routine will initiate the temperature conversion within
+ * a DS1820. There is a built in 750ms delay to allow the
+ * conversion to complete.
+ *
+ * To update all probes on the bus, use a statement such as this:
+ * probe[0]->convert_temperature(DS1820::all_devices);
+ *
+ * @param allows the fnction to apply to a specific device or
+ * to all devices on the 1-Wire bus.
+ */
+ void convert_temperature(devices device=this_device);
+
+ /** This function will return the probe temperature. This function
+ * uses the count remainding values to interpolate the temperature
+ * to about 1/150th of a degree. Whereas the probe is not spec to
+ * that precision. It does seem to give a smooth reading to the
+ * tenth of a degree.
+ *
+ * @param scale, may be either 'c' or 'f'
+ * @returns temperature for that scale
+ */
+ float temperature(char scale='c');
+
+ /** This function calculates the ROM checksum and compares it to the
+ * CRC value stored in ROM[7].
+ *
+ * @returns true if the checksum matches, otherwise false.
+ */
+ bool ROM_checksum_error();
+
+ /** This function calculates the RAM checksum and compares it to the
+ * CRC value stored in RAM[8].
+ *
+ * @returns true if the checksum matches, otherwise false.
+ */
+ bool RAM_checksum_error();
+
+ /** This funtion returns the values stored in the temperature
+ * alarm registers.
+ *
+ * @returns a 16 bit integer of TH (upper byte) and TL (lower byte).
+ */
+ int read_scratchpad();
+
+ /** This function will store the passed data into the DS1820's RAM.
+ * Note: It does NOT save the data to the EEPROM for retention
+ * during cycling the power off and on.
+ *
+ * @param a 16 bit integer of TH (upper byte) and TL (lower byte).
+ */
+ void write_scratchpad(int data);
+
+ /** This function will transfer the TH and TL registers from the
+ * DS1820's RAM into the EEPROM.
+ * Note: There is a built in 10ms delay to allow for the
+ * completion of the EEPROM write cycle.
+ *
+ * @param allows the fnction to apply to a specific device or
+ * to all devices on the 1-Wire bus.
+ */
+ void store_scratchpad(devices device=this_device);
+
+ /** This function will copy the stored values from the EEPROM
+ * into the DS1820's RAM locations for TH and TL.
+ *
+ * @param allows the fnction to apply to a specific device or
+ * to all devices on the 1-Wire bus.
+ */
+ int recall_scratchpad(devices device=this_device);
+
+ /** This function will return the type of power supply for
+ * a specific device. It can also be used to query all devices
+ * looking for any device that is parasite powered.
+ *
+ * @returns true if the device (or all devices) are Vcc powered,
+ * returns false if the device (or ANY device) is parasite powered.
+ */
+ bool read_power_supply(devices device=this_device);
+
+private:
+ bool _parasite_power;
+ char CRC_byte (char CRC, char byte );
+ bool onewire_reset();
+ void match_ROM();
+ void skip_ROM();
+ bool search_ROM_routine(char command);
+ void onewire_bit_out (bool bit_data);
+ void onewire_byte_out(char data);
+ bool onewire_bit_in();
+ char onewire_byte_in();
+
+protected:
+ DigitalInOut _datapin;
+ DigitalOut _parasitepin;
+};
+
+
+#endif