André Nunes
ze
Dependencies: mbed WakeUp OneWire
Diff: DS1820.cpp
- Revision:
- 2:15f2d7d650bb
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/DS1820.cpp Sun Nov 22 20:11:11 2020 +0000
@@ -0,0 +1,420 @@
+/*
+ * 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
+ * ThisThread::sleep_for(1000);// 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
+ * ThisThread::sleep_for(1000); // 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, int sample_point_us /* = 13 */) {
+ oneWire = new OneWire(pin, sample_point_us);
+ 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();
+ //ThisThread::sleep_for(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);
+}
+
+