Benoit Agache
c
Diff: DS1820.cpp
- Revision:
- 2:ee820a991b95
- Parent:
- 1:6a427f54e82c
- Child:
- 3:8f2b7f4940b5
--- a/DS1820.cpp Wed Dec 14 20:22:16 2011 +0000
+++ b/DS1820.cpp Thu Dec 15 19:07:36 2011 +0000
@@ -1,390 +0,0 @@
-#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
- int delay_time = 750; // Default delay time
- char resolution;
- if (device==all_devices)
- skip_ROM(); // Skip ROM command, will convert for ALL devices
- else {
- match_ROM();
- if (FAMILY_CODE == FAMILY_CODE_DS18B20 ) {
- resolution = RAM[4] & 0x60;
- if (resolution == 0x00) // 9 bits
- delay_time = 94;
- if (resolution == 0x20) // 10 bits
- delay_time = 188;
- if (resolution == 0x40) // 11 bits. Note 12bits uses the 750ms default
- delay_time = 375;
- }
- }
- onewire_byte_out( 0x44); // perform temperature conversion
- if (_parasite_power)
- _parasitepin = 1; // Parasite power strong pullup
- wait_ms(delay_time);
- 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();
- }
-}
-
-bool DS1820::set_configuration_bits(unsigned int resolution) {
- bool answer = false;
- resolution = resolution - 9;
- if (resolution < 4) {
- resolution = resolution<<5; // align the bits
- RAM[4] = (RAM[4] & 0x60) | resolution; // mask out old data, insert new
- write_scratchpad ((RAM[2]<<8) + RAM[3]);
-// store_scratchpad (DS1820::this_device); // Need to test if this is required
- answer = true;
- }
- return answer;
-}
-
-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)
- if ( FAMILY_CODE == FAMILY_CODE_DS18B20 ) {
- onewire_byte_out(RAM[4]); // Configuration register
- }
-}
-
-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
- }
- answer = reading +0.0; // convert to floating point
- if ( FAMILY_CODE == FAMILY_CODE_DS18B20 ) {
- answer = answer / 8.0;
- }
- else {
- remaining_count = RAM[6];
- count_per_degree = RAM[7];
- 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();
-}