mirror of
https://github.com/sergeyyarkov/attiny45v_thermometer.git
synced 2026-10-11 10:19:03 +03:00
107 lines
2.7 KiB
C
107 lines
2.7 KiB
C
#include "dstemperature.h"
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uint8_t DallasTemp_ReadScratchpad(uint8_t *scratchpad) {
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OneWire_SkipROM();
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OneWire_WriteByte(DS18B20_CMD_RSCRATCHPAD);
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for (uint8_t i = 0; i < 8; i++) {
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scratchpad[i] = OneWire_ReadByte();
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}
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uint8_t calculated_crc = OneWire_CRC8_Update(scratchpad, 8);
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uint8_t crc = OneWire_ReadByte();
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if (calculated_crc != crc) return 0;
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return 1;
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}
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// TODO parasite power
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uint8_t DallasTemp_CopyScratchpad(void) {
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if (!OneWire_Presence()) return 0;
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OneWire_SkipROM();
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OneWire_WriteByte(DS18B20_CMD_CPSCRATCHPAD);
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_delay_ms(10);
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return 1;
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}
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void DallasTemp_WriteScratchpad(uint8_t *data) {
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uint8_t i = 3;
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OneWire_SkipROM();
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OneWire_WriteByte(DS18B20_CMD_WSCRATCHPAD);
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do {
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OneWire_WriteByte(*data++);
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} while (--i);
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DallasTemp_CopyScratchpad();
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}
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void DallasTemp_SetResolution(DallasSensor *Sensor, uint8_t r) {
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DallasTemp_ReadScratchpad(Sensor->SCRATCHPAD);
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uint8_t data[3] = { Sensor->SCRATCHPAD[2], Sensor->SCRATCHPAD[3], 0x7f };
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switch(r) {
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case 12:
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data[2] = 0x7f;
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break;
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case 11:
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data[2] = 0x5f;
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break;
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case 10:
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data[2] = 0x3f;
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break;
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case 9:
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data[2] = 0x1f;
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break;
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default:
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data[2] = 0x7f;
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break;
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}
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DallasTemp_WriteScratchpad(data);
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}
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uint8_t DallasTemp_Convert(void) {
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if (!OneWire_Presence()) return 0;
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OneWire_WriteByte(ONE_WIRE_SKIPROM);
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OneWire_WriteByte(DS18B20_CMD_CONVERTTEMP);
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return 1;
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}
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uint8_t DallasTemp_CheckError(DallasSensor* Sensor) {
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if (!OneWire_Presence()) return 1;
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OneWire_ReadROM(Sensor->ROM);
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if (Sensor->ROM[0] != DS18B20_CONST_FAMILY_CODE) return 1;
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return 0;
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}
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void DallasTemp_GetTemperature(DallasSensor *Sensor) {
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if (!DallasTemp_Convert()) return;
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if (!(~Sensor->SCRATCHPAD[4] & 0x60)) {
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_delay_ms(750);
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} else if (!(~Sensor->SCRATCHPAD[4] & 0x40)) {
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_delay_ms(375);
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} else if (!(~Sensor->SCRATCHPAD[4] & 0x20)) {
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_delay_ms(188);
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} else {
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_delay_ms(94);
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}
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if (!DallasTemp_ReadScratchpad(Sensor->SCRATCHPAD)) return;
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Sensor->TEMPERATURE = ((Sensor->SCRATCHPAD[1] << 8) | Sensor->SCRATCHPAD[0]) / 16;
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/*
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* Двойное дополнение для дробной части если минусовая температура:
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* проверяем что последние пять битов в старшем байте температуры стоят в единице
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*/
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if (Sensor->SCRATCHPAD[1] & 0xf8) Sensor->SCRATCHPAD[0] = -Sensor->SCRATCHPAD[0];
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/**
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* Получаем дробную часть через битовую маску 0x0f, умножаем для получения точности.
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*/
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Sensor->TEMPERATURE_FRACTION = ((Sensor->SCRATCHPAD[0] & 0x0f) * 1000) / 16;
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} |