HomeEnergyMeter/STM32/Core/Src/oneWire.c

#include "stm32f1xx_hal.h"
#include "oneWireDriver.h"
#include<stdio.h>
#include<stdbool.h>

// global search state
static unsigned char ROM_NO[8];
static uint8_t LastDiscrepancy;
static uint8_t LastFamilyDiscrepancy;
static bool LastDeviceFlag;

void reset_oneWireSearch()
{
	// reset the search state
	LastDiscrepancy = 0;
	LastDeviceFlag = false;
	LastFamilyDiscrepancy = 0;
	for(int i = 7; ; i--) {
		ROM_NO[i] = 0;
		if ( i == 0) break;
	}
}


bool oneWireSearch(uint64_t *newAddr )
{
	const bool search_mode = true;
	uint8_t id_bit_number;
	uint8_t last_zero, rom_byte_number;
	bool    search_result;
	uint8_t id_bit, cmp_id_bit;

	unsigned char rom_byte_mask, search_direction;

	// initialize for search
	id_bit_number = 1;
	last_zero = 0;
	rom_byte_number = 0;
	rom_byte_mask = 1;
	search_result = false;

	// if the last call was not the last one
	if (!LastDeviceFlag) {
		// 1-Wire reset
		if (!oneWire_init()) {
			// reset the search
			LastDiscrepancy = 0;
			LastDeviceFlag = false;
			LastFamilyDiscrepancy = 0;
			return false;
		}

		// issue the search command
		if (search_mode == true) {
			writeByte(0xF0);   // NORMAL SEARCH
		} else {
			writeByte(0xEC);   // CONDITIONAL SEARCH
		}

		// loop to do the search
		do
		{
			// read a bit and its complement
			id_bit = readSlot();
			cmp_id_bit = readSlot();

			// check for no devices on 1-wire
			if ((id_bit == 1) && (cmp_id_bit == 1)) {
				break;
			} else {
				// all devices coupled have 0 or 1
				if (id_bit != cmp_id_bit) {
					search_direction = id_bit;  // bit write value for search
				} else {
					// if this discrepancy if before the Last Discrepancy
					// on a previous next then pick the same as last time
					if (id_bit_number < LastDiscrepancy) {
						search_direction = ((ROM_NO[rom_byte_number] & rom_byte_mask) > 0);
					} else {
						// if equal to last pick 1, if not then pick 0
						search_direction = (id_bit_number == LastDiscrepancy);
					}
					// if 0 was picked then record its position in LastZero
					if (search_direction == 0) {
						last_zero = id_bit_number;

						// check for Last discrepancy in family
						if (last_zero < 9)
							LastFamilyDiscrepancy = last_zero;
					}
				}

				// set or clear the bit in the ROM byte rom_byte_number
				// with mask rom_byte_mask
				if (search_direction == 1)
					ROM_NO[rom_byte_number] |= rom_byte_mask;
				else
					ROM_NO[rom_byte_number] &= ~rom_byte_mask;

				// serial number search direction write bit
				writeSlot(search_direction);

				// increment the byte counter id_bit_number
				// and shift the mask rom_byte_mask
				id_bit_number++;
				rom_byte_mask <<= 1;

				// if the mask is 0 then go to new SerialNum byte rom_byte_number and reset mask
				if (rom_byte_mask == 0) {
					rom_byte_number++;
					rom_byte_mask = 1;
				}
			}
		}
		while(rom_byte_number < 8);  // loop until through all ROM bytes 0-7

		// if the search was successful then
		if (!(id_bit_number < 65)) {
			// search successful so set LastDiscrepancy,LastDeviceFlag,search_result
			LastDiscrepancy = last_zero;

			// check for last device
			if (LastDiscrepancy == 0) {
				LastDeviceFlag = true;
			}
			search_result = true;
		}
	}

	// if no device found then reset counters so next 'search' will be like a first
	if (!search_result || !ROM_NO[0]) {
		LastDiscrepancy = 0;
		LastDeviceFlag = false;
		LastFamilyDiscrepancy = 0;
		search_result = false;
	} else {
		for (int i = 0; i < 8; i++) {
			(*newAddr)<<=8;
			(*newAddr) |= ROM_NO[i];
		}
	}
	return search_result;
}


static void sendROMCode(const uint64_t adr){
	for( uint8_t i = 8; i>0; i--) writeByte( (uint8_t)(adr >> ((i-1)*8))&0xFF );
}

static uint32_t initReadTemp(const uint64_t adr)
{
	uint32_t noOfSlots = 0;
	oneWire_init();
	writeByte(0x55); // match ROM
	sendROMCode(adr);
	writeByte(0x44); // convert t
	while( readSlot() == 0 ) {
		noOfSlots++;
		us_delay(1000);
	}
	return noOfSlots;
}

float readTemperature(const uint64_t adr)
{
	uint32_t time_ms = initReadTemp(adr);

	oneWire_init();
	writeByte(0x55); // skip ROM
	sendROMCode(adr);
	writeByte(0xBE); // Read Scratchpad
	uint8_t b0 = readByte();
	uint8_t b1 = readByte();
	uint8_t b2 = readByte();
	uint8_t b3 = readByte();
	uint8_t b4 = readByte();
	uint8_t b5 = readByte();
	uint8_t b6 = readByte();
	uint8_t b7 = readByte();
	uint16_t raw = (int16_t)((b1 << 8) | b0);
	uint16_t cfg = (b4 & 0x60);
	// at lower res, the low bits are undefined, so let's zero them
	if (cfg == 0x00) raw = raw & ~7;  // 9 bit resolution, 93.75 ms
	else if (cfg == 0x20) raw = raw & ~3; // 10 bit res, 187.5 ms
	else if (cfg == 0x40) raw = raw & ~1; // 11 bit res, 375 ms
	//// default is 12 bit resolution, 750 ms conversion time
	float temperature = (float)raw / 16.0;
	printf("%lumS  :  %02X %02X %02X %02X %02X",time_ms,b0,b1,b2,b3,b4);
	printf(" %02X %02X %02X = %.02f\n",b5,b6,b7,temperature);
	return temperature;
}