uint8_t DS18B20_Manager_readScratchpad(DS18B20_Manager_t *a_pMe)
{
uint8_t retVal = DS18B20_OK;
OneWireBusStatus_t oneWireBusStatus;
uint8_t u8crc8 = 0; // CRC8 initial value
uint8_t u8Idx;
// Send reset pulse to sensor
oneWireBusStatus = OneWireMaster_reset(a_pMe->oneWireBusMasterPtr);
if (OneWireBus_DEVICE_PRESENT == oneWireBusStatus)
{
// Device is present. Issue Skip ROM command to address all devices.
OneWireBusMaster_writeByte(a_pMe->oneWireBusMasterPtr, SKIP_ROM_18B20);
// Issue read scratchpad function command
OneWireBusMaster_writeByte(a_pMe->oneWireBusMasterPtr, READ_SCRATCHPAD_18B20);
// Read scratchpad: 9 bytes
for (u8Idx = 0; u8Idx < SCRATCHPAD_SIZE_18B20; u8Idx++)
{
a_pMe->scratchpad[u8Idx] = OneWireBusMaster_readByte(a_pMe->oneWireBusMasterPtr);
}
// Calculate CRC8 for received scratchpad data
for (u8Idx = 0; u8Idx < (SCRATCHPAD_SIZE_18B20 - 1); u8Idx++)
{
u8crc8 = OneWire_crc8(a_pMe->scratchpad[u8Idx], u8crc8);
}
// Check data integrity
if (u8crc8 != a_pMe->scratchpad[SCRATCHPAD_SIZE_18B20-1])
{
retVal = DS18B20_CRC_ERROR;
}
else
{
// Nothing to do
}
}
else
{
// No device present or short circuit
retVal = DS18B20_ERROR;
}
return retVal;
}
void Sensors_Poll(void)
{
/* This function must be call 100 ms periods */
// // check warning level
// if (sensors.Gas > __flash_data._thesis._data.Gas ||
// sensors.Lighting > __flash_data._thesis._data.Lighting ||
// sensors.TempC > __flash_data._thesis._data.TempC)
// {
// // turn on buzzer if enable
// if (__flash_data._thesis._output.Buzzer)
// {
// TurnBuzzerOn();
// }
// // turn on speaker if enable
// if (__flash_data._thesis._output.Speaker)
// {
// TurnSpeakerOn();
// }
// // turn on relay if enable
// if (__flash_data._thesis._output.Relay)
// {
// TurnRelayOn();
// }
// }
// else
// {
// // turn off buzzer if enable
// if (__flash_data._thesis._output.Buzzer)
// {
// TurnBuzzerOff();
// }
// // turn off speaker if enable
// if (__flash_data._thesis._output.Speaker)
// {
// TurnSpeakerOff();
// }
// // turn off relay if enable
// if (__flash_data._thesis._output.Relay)
// {
// TurnRelayOff();
// }
// }
// recalculate sensor values
sensors.Gas = (ADCConvertedValue[0] + ADCConvertedValue[2] + ADCConvertedValue[4])/3;
sensors.Lighting = (ADCConvertedValue[1] + ADCConvertedValue[3] + ADCConvertedValue[5])/3;
#if SENSORS_DEBUG
if (SS_Debug_delay == 0)
{
USART1_SendStr("\nGas Value: ");
USART1_SendFloat(sensors.Gas);
USART1_SendStr(" kppm.\n");
USART1_SendStr("\nLighting Value: ");
USART1_SendFloat(sensors.Lighting);
USART1_SendStr(" Lux.\n");
SS_Debug_delay = 10;
}
else
{
SS_Debug_delay--;
}
#endif
switch (OW_CurrState)
{
case OneWire_Idle:
if ( !OneWire_search(addr)) {
#if SENSORS_DEBUG
USART1_SendStr("\nNo more addresses.\n");
USART1_SendStr("\n\n");
#endif
OneWire_reset_search();
// delay 300 ms before try again
OW_CurrState = OneWire_Delay;
OW_NextState = OneWire_Idle;
OW_Delay = 3;
}
else
{
OW_CurrState = OneWire_Delay;
OW_NextState = OneWire_StartConv;
OW_Delay = 3;
}
break;
case OneWire_Delay:
if (OW_Delay == 0)
{
// switch state
OW_CurrState = OW_NextState;
}
else
{
OW_Delay--;
}
break;
case OneWire_StartConv:
#if SENSORS_DEBUG
USART1_SendStr("ROM =");
for( i = 0; i < 8; i++) {
USART1_SendChar(' ');
USART1_SendByte(addr[i], HEX);
}
#endif
if (OneWire_crc8(addr, 7) != addr[7]) {
#if SENSORS_DEBUG
USART1_SendStr("\nCRC is not valid!\n");
#endif
// goto delay 300ms before switch to idle to find device again
OW_CurrState = OneWire_Delay;
OW_NextState = OneWire_Idle;
OW_Delay = 3;
}
#if SENSORS_DEBUG
USART1_SendStr("\n\n");
#endif
// the first ROM byte indicates which chip
switch (addr[0]) {
case 0x10:
#if SENSORS_DEBUG
USART1_SendStr("\n Chip = DS18S20\n"); // or old DS1820
#endif
type_s = 1;
break;
case 0x28:
#if SENSORS_DEBUG
USART1_SendStr("\n Chip = DS18B20\n");
#endif
type_s = 0;
break;
case 0x22:
#if SENSORS_DEBUG
USART1_SendStr("\n Chip = DS1822\n");
#endif
type_s = 0;
break;
default:
#if SENSORS_DEBUG
USART1_SendStr("\nDevice is not a DS18x20 family device.\n");
#endif
// goto delay 300ms before switch to idle to find device again
OW_CurrState = OneWire_Delay;
OW_NextState = OneWire_Idle;
OW_Delay = 3;
break;
}
OneWire_reset();
OneWire_select(addr);
OneWire_write(0x44, 1); // start conversion, with parasite power on at the end
// goto delay 1000ms before read data
OW_CurrState = OneWire_Delay;
OW_NextState = OneWire_GetValue;
OW_Delay = 10;
break;
case OneWire_GetValue:
present = OneWire_reset();
OneWire_select(addr);
OneWire_write(0xBE, 0); // Read Scratchpad
#if SENSORS_DEBUG
USART1_SendStr(" Data = ");
USART1_SendByte(present, HEX);
USART1_SendStr(" ");
#endif
for ( i = 0; i < 9; i++) { // we need 9 bytes
data[i] = OneWire_read();
#if SENSORS_DEBUG
USART1_SendByte(data[i], HEX);
USART1_SendStr(" ");
#endif
}
#if SENSORS_DEBUG
USART1_SendStr(" CRC=");
USART1_SendByte(OneWire_crc8(data, 8), HEX);
USART1_SendStr("\n\n");
#endif
// Convert the data to actual temperature
// because the result is a 16 bit signed integer, it should
// be stored to an "int16_t" type, which is always 16 bits
// even when compiled on a 32 bit processor.
int16_t raw = (data[1] << 8) | data[0];
if (type_s) {
raw = raw << 3; // 9 bit resolution default
if (data[7] == 0x10) {
// "count remain" gives full 12 bit resolution
raw = (raw & 0xFFF0) + 12 - data[6];
}
} else {
byte cfg = (data[4] & 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
}
celsius = (float)raw / 16.0;
fahrenheit = celsius * 1.8 + 32.0;
#if SENSORS_DEBUG
USART1_SendStr(" Temperature = ");
USART1_SendFloat(celsius);
USART1_SendStr(" Celsius, ");
USART1_SendFloat(fahrenheit);
USART1_SendStr(" Fahrenheit\n");
#endif
sensors.TempC = celsius;
// goto delay 300ms before next convert
OW_CurrState = OneWire_Delay;
OW_NextState = OneWire_StartConv;
OW_Delay = 3;
break;
} // switch
}
