Dallas' DS1820 family temperature sensor. For more details see [https://developer.mbed.org/users/hudakz/code/DS1820/wiki/Homepage]
Dependents: BLE_nRF24L01 frdm_serialfgmp gather_sensor_data UltiSaverController ... more
Some programs using the DS1820 library:
Import programDS1820_Hello
Simple DS1820 sensor demo showing how to use the DS1820 library [https://developer.mbed.org/users/hudakz/code/DS1820/]
Import programBLE_nRF24L01
Bluetooth Low Energy (BLE) beacon with nRF24L01(+). Data is received and displayed by Android device (Android app source code is attached).
Examples of use:
Single DS1820 sensor
/* * Single DS1820 sensor GPIO driven * * Note: Don't forget to connect a 4.7k Ohm resistor * between the DS1820's data pin and the +3.3V pin * * ---------------- * | | -----------------------> +3.3V * | MBED BOARD | | * | | | ------ * | +3.3V |--o--| 4.7k |------- * | | ------ | * | | | * | | | * | | | * | | | * | GPIO |--------------------o-----> 1-wire bus/line * | | * | | * | GND |--------------------------> GND * | | * ---------------- * */ #include "mbed.h" #include "DS1820.h" Serial serial(USBTX, USBRX); int main() { DS1820 ds1820(D8); // substitute D8 with actual mbed pin name connected to the DS1820 data pin if(ds1820.begin()) { while(1) { ds1820.startConversion(); // start temperature conversion ThisThread::sleep_for(1000); // let DS1820 complete the temperature conversion serial.printf("temp = %3.1f\r\n", ds1820.read()); // read temperature } } else serial.printf("No DS1820 sensor found!\r\n"); }
Single DS1820 sensor. Data integrity is assured by performing CRC.
/* * Single DS1820 sensor GPIO driven + performing CRC * * Note: Don't forget to connect a 4.7k Ohm resistor * between the DS1820's data pin and the +3.3V pin * * ---------------- * | | -----------------------> +3.3V * | MBED BOARD | | * | | | ------ * | +3.3V |--o--| 4.7k |------- * | | ------ | * | | | * | | | * | | | * | | | * | GPIO |--------------------o-----> 1-wire bus/line * | | * | | * | GND |--------------------------> GND * | | * ---------------- * */ #include "mbed.h" #include "DS1820.h" Serial serial(USBTX, USBRX); int main() { DS1820 ds1820(D8); // substitute D8 with actual mbed pin name connected to the DS1820 data pin float temp = 0; int error = 0; if(ds1820.begin()) { while(1) { ds1820.startConversion(); // start temperature conversion ThisThread::sleep_for(1000); // let DS1820 complete the temperature conversion error = ds1820.read(temp); // read temperature from DS1820 and perform cyclic redundancy check (CRC) switch(error) { case 0: // no errors -> 'temp' contains the value of measured temperature serial.printf("temp = %3.1f\r\n", temp); break; case 1: // no sensor present -> 'temp' is not updated serial.printf("no sensor present\n\r"); break; case 2: // CRC error -> 'temp' is not updated serial.printf("CRC error\r\n"); } } } else serial.printf("No DS1820 sensor found!\r\n"); }
Several DS1820 sensors connected to the same 1-wire bus.
/* * Multiple sensors GPIO driven * * Note: Don't forget to connect a 4.7k Ohm resistor * between the 1-wire bus data line and the +3.3V rail * * ---------------- * | | -----------------------> +3.3V * | MBED BOARD | | * | | | ------ * | +3.3V |--o--| 4.7k |------- * | | ------ | * | | | * | | | * | | | * | | | * | GPIO |--------------------o-----> 1-wire bus/line * | | * | | * | GND |--------------------------> GND * | | * ---------------- * */ #include "mbed.h" #include "DS1820.h" #define MAX_SENSOSRS 32 // max number of DS1820 sensors to be connected to the 1-wire bus (max 256) DS1820* ds1820[MAX_SENSOSRS]; Serial pc(USBTX, USBRX); DigitalOut led(LED1); OneWire oneWire(D8); // substitute D8 with the actual pin name connected to the 1-wire bus int sensorsFound = 0; // counts the actually found DS1820 sensors int main() { pc.printf("\r\n--Starting--\r\n"); //Enumerate (i.e. detect) DS1820 sensors on the 1-wire bus for (sensorsFound = 0; sensorsFound < MAX_SENSOSRS; sensorsFound++) { ds1820[sensorsFound] = new DS1820(&oneWire); if (!ds1820[sensorsFound]->begin()) { delete ds1820[sensorsFound]; break; } } switch (sensorsFound) { case 0: pc.printf("No DS1820 sensor found!\r\n"); return -1; case 1: pc.printf("One DS1820 sensor found.\r\n"); break; default: pc.printf("Found %d DS1820 sensors.\r\n", sensorsFound); } while (1) { pc.printf("----------------\r\n"); for (int i = 0; i < sensorsFound; i++) ds1820[i]->startConversion(); // start temperature conversion from analog to digital ThisThread::sleep_for(1000); // let DS1820 sensors complete the temperature conversion for (int i = 0; i < sensorsFound; i++) { if (ds1820[i]->isPresent()) pc.printf("temp[%d] = %3.1f%cC\r\n", i, ds1820[i]->read(), 176); // read temperature } } }
Several DS1820 sensors connected to the same 1-wire bus. UART is used to implement the bus
/* * Multiple sensors UART driven: * * UART is driving the 1-Wire Bus Master according to Maxim Integrated application note * * https://www.maximintegrated.com/en/design/technical-documents/tutorials/2/214.html * * In addition to the 4.7k Ohm resistor between the 1-wire data bus/line and the +3.3V pin, * a 470 Ohm resistor shall be tied to the UART's tx and rx pin. UART's rx pin is then used * as 1-wire data bus/line. * * ---------------- * | | -----------------------> +3.3V * | MBED BOARD | | * | | | ------ * | +3.3V |--o--| 4.7k |------- * | | ------ | * | | ------ | * | UART TX |-----| 470 |--- | * | | ------ | | * | | | | * | UART RX |----------------o---o-----> 1-wire bus/line * | | * | | * | GND |--------------------------> GND * | | * ---------------- * */ #include "mbed.h" #include "DS1820.h" #define MAX_SENSOSRS 32 // max number of DS1820 sensors to be connected to the 1-wire bus (max 256) DS1820* ds1820[MAX_SENSOSRS]; DigitalOut led(LED1); OneWire oneWire(p9, p10); // LPC1768 (UART Tx pin, UART Rx pin) //OneWire oneWire(PA_0, PA_1); // NUCLE0-F446RE (UART Tx pin, UART Rx pin) int sensorsFound = 0; // counts the actually found DS1820 sensors /** * @brief * @note * @param * @retval */ int main() { printf("\r\n--Starting--\r\n"); //Enumerate (i.e. detect) DS1820 sensors on the 1-wire bus for (sensorsFound = 0; sensorsFound < MAX_SENSOSRS; sensorsFound++) { ds1820[sensorsFound] = new DS1820(&oneWire); if (!ds1820[sensorsFound]->begin()) { delete ds1820[sensorsFound]; break; } } switch (sensorsFound) { case 0: printf("No DS1820 sensor found!\r\n"); return -1; case 1: printf("One DS1820 sensor found.\r\n"); break; default: printf("Found %d DS1820 sensors.\r\n", sensorsFound); } while (1) { led = !led; printf("----------------\r\n"); for (int i = 0; i < sensorsFound; i++) ds1820[i]->startConversion(); // start temperature conversion from analog to digital #if (MBED_MAJOR_VERSION > 5) ThisThread::sleep_for(1s); #else wait(1); #endif for (int i = 0; i < sensorsFound; i++) { if (ds1820[i]->isPresent()) printf("temp[%d] = %3.1f%cC\r\n", i, ds1820[i]->read(), 176); // read temperature } } }
Diff: DS1820.cpp
- Revision:
- 0:433af64321d5
- Child:
- 1:e4689408d617
diff -r 000000000000 -r 433af64321d5 DS1820.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/DS1820.cpp Sun Mar 15 14:16:16 2015 +0000 @@ -0,0 +1,201 @@ +#include "DS1820.h" + +#define DEBUG 1 + +#if DEBUG +extern Serial serial; +#endif + +/** + * @brief Constructs a generic DS1820 sensor + * @note begin() must be called to detect and initialize the actual model + * @param Name of data pin + * @retval + */ +DS1820::DS1820(PinName pin) : + oneWire(pin) { + present = 0; + type_s = 0; +} + +/** + * @brief Constructs a specific model + * @note No need to call begin() to detect and initialize the model + * @param One character model name: 'S', 's', 'B' or 'b' + * Name of data pin + * @retval + */ +DS1820::DS1820(char model, PinName pin) : + oneWire(pin) { + if((model == 'S') or (model == 's')) { + present = 1; + type_s = 1; + } + else if((model == 'B') or (model == 'b')) { + present = 1; + type_s = 0; + } + else + present = 0; +} + +/** + * @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) { + oneWire.reset_search(); + wait_ms(250); + if(!oneWire.search(addr)) { +#if DEBUG + serial.printf("No addresses.\r\n"); +#endif + oneWire.reset_search(); + wait_ms(250); + return false; + } + +#if DEBUG + serial.printf("ROM ="); + for(uint8_t i = 0; i < 8; i++) { + serial.printf(" %x", addr[i]); + } + serial.printf("\r\n"); +#endif + + if(OneWire::crc8(addr, 7) == addr[7]) { + present = 1; + + // the first ROM byte indicates which chip + switch(addr[0]) { + case 0x10: + type_s = 1; +#if DEBUG + serial.printf("DS18S20 or old DS1820\r\n"); +#endif + break; + + case 0x28: + type_s = 0; +#if DEBUG + serial.printf("DS18B20\r\n"); +#endif + break; + + case 0x22: + type_s = 0; +#if DEBUG + serial.printf("DS1822\r\n"); +#endif + break; + + default: + present = 0; +#if DEBUG + serial.printf("Device doesn't belong to the DS1820 family\r\n"); + return false; +#endif + } + return true; + } +#if DEBUG + else { + serial.printf("Invalid CRC!\r\n"); + return false; + } +#endif +} + +/** + * @brief Starts temperature conversion + * @note The time to complete the converion depends on the selected resolusion + * @param + * @retval + */ +void DS1820::startConversion(void) { + if(present) { + oneWire.reset(); + + //oneWire.select(addr); + oneWire.skip(); + oneWire.write(0x44); //start 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.skip(); + oneWire.write(0xBE); // to read Scratchpad + for(uint8_t i = 0; i < 9; i++) + data[i] = oneWire.read(); + + // Convert the raw bytes to a 16bit signed fixed point value : + // 1 sign bit, 7 integer bits, 8 fractional bits (two’s compliment + // ie. the LSB of the 16bit binary number represents 1/256th of a unit). + + uint16_t* p_word = reinterpret_cast < uint16_t * > (&data[0]); + +#if DEBUG + serial.printf("raw = %#x\r\n", *p_word); +#endif + + + if(type_s) { + *p_word = *p_word << 3; // default 9 bit resolution + if(data[7] == 0x10) { + + // "count remain" gives full 12 bit resolution + *p_word = (*p_word & 0xFFF0) + 12 - data[6]; + } + + *p_word = *p_word << 4; + return(toFloat(*p_word)); + } + else { + uint8_t cfg = (data[4] & 0x60); + // at lower res, the low bits are undefined, so let's zero them + + if(cfg == 0x00) + *p_word = *p_word &~7; // 9 bit resolution, 93.75 ms + else + if(cfg == 0x20) + *p_word = *p_word &~3; // 10 bit res, 187.5 ms + else + if(cfg == 0x40) + *p_word = *p_word &~1; // 11 bit res, 375 ms + *p_word = *p_word << 4; // default is 12 bit resolution + return(toFloat(*p_word)); + } + } + else + return 0; +} + +/** + * @brief Converts a 16bit signed fixed point value to float + * @note The 16bit unsigned integer represnts actually + * a 16bit signed fixed point value: + * 1 sign bit, 7 integer bits, 8 fractional bits + * (two’s compliment ie. the LSB of the 16bit binary number + * represents 1/256th of a unit). + * @param 16bit unsigned integer + * @retval Floating point temperature value + */ +float DS1820::toFloat(uint16_t word) { + //word = word << 4; + if(word & 0x8000) + return (-float(uint16_t(~word + 1)) / 256.0f); + else + return (float(word) / 256.0f); +} +