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Coffeemaker controller
Diff: DS1820.cpp
- Revision:
- 0:17c5e4f9a805
diff -r 000000000000 -r 17c5e4f9a805 DS1820.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/DS1820.cpp Sat Sep 26 00:30:09 2020 +0000 @@ -0,0 +1,419 @@ +/* + * Dallas' DS1820 family temperature sensor. + * This library depends on the OneWire library (Dallas' 1-Wire bus protocol implementation) + * available at <http://developer.mbed.org/users/hudakz/code/OneWire/> + * + * Example of use: + * + * Single sensor. + * + * #include "mbed.h" + * #include "DS1820.h" + * + * Serial pc(USBTX, USBRX); + * DigitalOut led(LED1); + * OneWire oneWire(D8); // substitute D8 with actual mbed pin name connected 1-wire bus + * float temp = 0; + * int result = 0; + * + * int main() + * { + * pc.printf("\r\n--Starting--\r\n"); + * if (ds1820.begin()) { + * while (1) { + * ds1820.startConversion(); // start temperature conversion from analog to digital + * wait(1.0); // let DS1820 complete the temperature conversion + * result = ds1820.read(temp); // read temperature from DS1820 and perform cyclic redundancy check (CRC) + * switch (result) { + * case 0: // no errors -> 'temp' contains the value of measured temperature + * pc.printf("temp = %3.1f%cC\r\n", temp, 176); + * break; + * + * case 1: // no sensor present -> 'temp' is not updated + * pc.printf("no sensor present\n\r"); + * break; + * + * case 2: // CRC error -> 'temp' is not updated + * pc.printf("CRC error\r\n"); + * } + * + * led = !led; + * } + * } + * else + * pc.printf("No DS1820 sensor found!\r\n"); + * } + * + * + * More sensors connected to the same 1-wire bus. + * + * #include "mbed.h" + * #include "DS1820.h" + * + * #define SENSORS_COUNT 64 // number of DS1820 sensors to be connected to the 1-wire bus (max 256) + * + * Serial pc(USBTX, USBRX); + * DigitalOut led(LED1); + * OneWire oneWire(D8); // substitute D8 with actual mbed pin name connected to the DS1820 data pin + * DS1820* ds1820[SENSORS_COUNT]; + * int sensors_found = 0; // counts the actually found DS1820 sensors + * float temp = 0; + * int result = 0; + * + * int main() { + * int i = 0; + * + * pc.printf("\r\n Starting \r\n"); + * //Enumerate (i.e. detect) DS1820 sensors on the 1-wire bus + * for(i = 0; i < SENSORS_COUNT; i++) { + * ds1820[i] = new DS1820(&oneWire); + * if(!ds1820[i]->begin()) { + * delete ds1820[i]; + * break; + * } + * } + * + * sensors_found = i; + * + * if (sensors_found == 0) { + * pc.printf("No DS1820 sensor found!\r\n"); + * return -1; + * } + * else + * pc.printf("Found %d sensors.\r\n", sensors_found); + * + * while(1) { + * pc.printf("-------------------\r\n"); + * for(i = 0; i < sensors_found; i++) + * ds1820[i]->startConversion(); // start temperature conversion from analog to digital + * wait(1.0); // let DS1820s complete the temperature conversion + * for(int i = 0; i < sensors_found; i++) { + * if(ds1820[i]->isPresent()) + * pc.printf("temp[%d] = %3.1f%cC\r\n", i, ds1820[i]->read(), 176); // read temperature + * } + * } + * } + * + */ + +#include "DS1820.h" + +#define DEBUG 0 + +//* Initializing static members +uint8_t DS1820::lastAddr[8] = {0, 0, 0, 0, 0, 0, 0, 0}; +/** + * @brief Constructs a generic DS1820 sensor + * @note begin() must be called to detect and initialize the actual model + * @param pin: Name of data pin + * @retval + */ +DS1820::DS1820(PinName pin) { + oneWire = new OneWire(pin); + present = false; + model_s = false; +} + +/** + * @brief Constructs a generic DS1820 sensor + * @note begin() must be called to detect and initialize the actual model + * @param pin: Name of data pin + * @retval + */ +DS1820::DS1820(OneWire* wire) : + oneWire(wire) { + present = false; + model_s = false; +} + +/** + * @brief Detects and initializes the actual DS1820 model + * @note + * @param + * @retval true: if a DS1820 family sensor was detected and initialized + false: otherwise + */ +bool DS1820::begin(void) { +#if DEBUG + printf("lastAddr ="); + for(uint8_t i = 0; i < 8; i++) { + printf(" %x", lastAddr[i]); + } + printf("\r\n"); +#endif + if(!oneWire->search(lastAddr)) { +#if DEBUG + printf("No addresses.\r\n"); +#endif + oneWire->reset_search(); + wait_ms(250); + return false; + } + + for (int i = 0; i < 8; i++) + addr[i] = lastAddr[i]; + +#if DEBUG + printf("ROM ="); + for(uint8_t i = 0; i < 8; i++) { + printf(" %x", addr[i]); + } + printf("\r\n"); +#endif + + if(OneWire::crc8(addr, 7) == addr[7]) { + present = true; + + // the first ROM byte indicates which chip + switch(addr[0]) { + case 0x10: + model_s = true; +#if DEBUG + printf("DS18S20 or old DS1820\r\n"); +#endif + break; + + case 0x28: + model_s = false; +#if DEBUG + printf("DS18B20\r\n"); +#endif + break; + + case 0x22: + model_s = false; +#if DEBUG + printf("DS1822\r\n"); +#endif + break; + + default: + present = false; +#if DEBUG + printf("Device doesn't belong to the DS1820 family\r\n"); +#endif + return false; + } + return true; + } + else { +#if DEBUG + printf("Invalid CRC!\r\n"); +#endif + return false; + } +} + +/** + * @brief Informs about presence of a DS1820 sensor. + * @note begin() shall be called before using this function + * if a generic DS1820 instance was created by the user. + * No need to call begin() for a specific DS1820 instance. + * @param + * @retval true: when a DS1820 sensor is present + * false: otherwise + */ +bool DS1820::isPresent(void) { + return present; +} + +/** + * @brief Sets temperature-to-digital conversion resolution. + * @note The configuration register allows the user to set the resolution + * of the temperature-to-digital conversion to 9, 10, 11, or 12 bits. + * Defaults to 12-bit resolution for DS18B20. + * DS18S20 allows only 9-bit resolution. + * @param res: Resolution of the temperature-to-digital conversion in bits. + * @retval + */ +void DS1820::setResolution(uint8_t res) { + // keep resolution within limits + if(res > 12) + res = 12; + if(res < 9) + res = 9; + if(model_s) + res = 9; + + oneWire->reset(); + oneWire->select(addr); + oneWire->write_byte(0xBE); // to read Scratchpad + for(uint8_t i = 0; i < 9; i++) // read Scratchpad bytes + data[i] = oneWire->read_byte(); + + data[4] |= (res - 9) << 5; // update configuration byte (set resolution) + oneWire->reset(); + oneWire->select(addr); + oneWire->write_byte(0x4E); // to write into Scratchpad + for(uint8_t i = 2; i < 5; i++) // write three bytes (2nd, 3rd, 4th) into Scratchpad + oneWire->write_byte(data[i]); +} + +/** + * @brief Starts temperature conversion + * @note The time to complete the converion depends on the selected resolution: + * 9-bit resolution -> max conversion time = 93.75ms + * 10-bit resolution -> max conversion time = 187.5ms + * 11-bit resolution -> max conversion time = 375ms + * 12-bit resolution -> max conversion time = 750ms + * @param + * @retval + */ +void DS1820::startConversion(void) { + if(present) { + oneWire->reset(); + oneWire->select(addr); + oneWire->write_byte(0x44); //start temperature conversion + } +} + +/** + * @brief Reads temperature from the chip's Scratchpad + * @note + * @param + * @retval Floating point temperature value + */ +float DS1820::read(void) { + if(present) { + oneWire->reset(); + oneWire->select(addr); + oneWire->write_byte(0xBE); // to read Scratchpad + for(uint8_t i = 0; i < 9; i++) // reading scratchpad registers + data[i] = oneWire->read_byte(); + + // Convert the raw bytes to a 16-bit unsigned value + uint16_t* p_word = reinterpret_cast < uint16_t * > (&data[0]); + +#if DEBUG + printf("raw = %#x\r\n", *p_word); +#endif + + if(model_s) { + *p_word = *p_word << 3; // 9-bit resolution + if(data[7] == 0x10) { + + // "count remain" gives full 12-bit resolution + *p_word = (*p_word & 0xFFF0) + 12 - data[6]; + } + } + else { + uint8_t cfg = (data[4] & 0x60); // default 12-bit resolution + + // at lower resolution, the low bits are undefined, so let's clear them + if(cfg == 0x00) + *p_word = *p_word &~7; // 9-bit resolution + else + if(cfg == 0x20) + *p_word = *p_word &~3; // 10-bit resolution + else + if(cfg == 0x40) + *p_word = *p_word &~1; // 11-bit resolution + + } + + // Convert the raw bytes to a 16-bit signed fixed point value : + // 1 sign bit, 7 integer bits, 8 fractional bits (two’s compliment + // and the LSB of the 16-bit binary number represents 1/256th of a unit). + *p_word = *p_word << 4; + + // Convert to floating point value + return(toFloat(*p_word)); + } + else + return 0; +} + +/** + * @brief Reads temperature from chip's scratchpad. + * @note Verifies data integrity by calculating cyclic redundancy check (CRC). + * If the calculated CRC dosn't match the one stored in chip's scratchpad register + * the temperature variable is not updated and CRC error code is returned. + * @param temp: The temperature variable to be updated by this routine. + * (It's passed as reference to floating point.) + * @retval error code: + * 0 - no errors ('temp' contains the temperature measured) + * 1 - sensor not present ('temp' is not updated) + * 2 - CRC error ('temp' is not updated) + */ +uint8_t DS1820::read(float& temp) { + if(present) { + oneWire->reset(); + oneWire->select(addr); + oneWire->write_byte(0xBE); // to read Scratchpad + for(uint8_t i = 0; i < 9; i++) // reading scratchpad registers + data[i] = oneWire->read_byte(); + + if(oneWire->crc8(data, 8) != data[8]) // if calculated CRC does not match the stored one + { +#if DEBUG + for(uint8_t i = 0; i < 9; i++) + printf("data[%d]=0x%.2x\r\n", i, data[i]); +#endif + return 2; // return with CRC error + } + + // Convert the raw bytes to a 16bit unsigned value + uint16_t* p_word = reinterpret_cast < uint16_t * > (&data[0]); + +#if DEBUG + printf("raw = %#x\r\n", *p_word); +#endif + + if(model_s) { + *p_word = *p_word << 3; // 9 bit resolution, max conversion time = 750ms + if(data[7] == 0x10) { + + // "count remain" gives full 12 bit resolution + *p_word = (*p_word & 0xFFF0) + 12 - data[6]; + } + + // Convert the raw bytes to a 16bit signed fixed point value : + // 1 sign bit, 7 integer bits, 8 fractional bits (two's compliment + // and the LSB of the 16bit binary number represents 1/256th of a unit). + *p_word = *p_word << 4; + // Convert to floating point value + temp = toFloat(*p_word); + return 0; // return with no errors + } + else { + uint8_t cfg = (data[4] & 0x60); // default 12bit resolution, max conversion time = 750ms + + // at lower resolution, the low bits are undefined, so let's clear them + if(cfg == 0x00) + *p_word = *p_word &~7; // 9bit resolution, max conversion time = 93.75ms + else + if(cfg == 0x20) + *p_word = *p_word &~3; // 10bit resolution, max conversion time = 187.5ms + else + if(cfg == 0x40) + *p_word = *p_word &~1; // 11bit resolution, max conversion time = 375ms + + // Convert the raw bytes to a 16bit signed fixed point value : + // 1 sign bit, 7 integer bits, 8 fractional bits (two's complement + // and the LSB of the 16bit binary number represents 1/256th of a unit). + *p_word = *p_word << 4; + // Convert to floating point value + temp = toFloat(*p_word); + return 0; // return with no errors + } + } + else + return 1; // error, sensor is not present +} + +/** + * @brief Converts a 16-bit signed fixed point value to floating point value + * @note The 16-bit unsigned integer represnts actually + * a 16-bit signed fixed point value: + * 1 sign bit, 7 integer bits, 8 fractional bits (two’s complement + * and the LSB of the 16-bit binary number represents 1/256th of a unit). + * @param 16-bit unsigned integer + * @retval Floating point value + */ +float DS1820::toFloat(uint16_t word) { + if(word & 0x8000) + return (-float(uint16_t(~word + 1)) / 256.0f); + else + return (float(word) / 256.0f); +} +