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/*
* ThermocoupleSensor31856.cpp
*
* Created on: 27 Jun 2017
* Author: David
*/
#include "ThermocoupleSensor31856.h"
#include "RepRap.h"
#include "Platform.h"
#include "GCodes/GCodeBuffer/GCodeBuffer.h"
const uint32_t MAX31856_Frequency = 4000000; // maximum for MAX31865 is 5MHz
static const char * const TypeLetters = "BEJKNRST"; // MAX31856 mapping of AVGSEWL bits to thermocouple types
const uint8_t TypeK = 3;
// SPI modes:
// If the inactive state of SCL is LOW (CPOL = 0): (in the case of the MAX31865, this is sampled on the falling edge of CS):
// The MAX31856 changes data after the rising edge of CLK, and samples input data on the falling edge.
// This requires NCPHA = 0.
const uint8_t MAX31856_SpiMode = SPI_MODE_1;
// Define the minimum interval between readings
const uint32_t MinimumReadInterval = 100; // minimum interval between reads, in milliseconds
// Default configuration registers.
// CR0:
// CMODE=1 continuous conversion
// 1shot=0 no 1-shot conversion
// OCFAULT=01 open circuit detection enabled, input resistance <5K
// CJ=0 cold junction temperature sensing enabled
// FAULT=1 fault bit and output remain set until cleared explicitly
// FAULTCLR=1 clear any existing fault
// 50/60Hz=1 reject 50Hz (configurable via F parameter)
const uint8_t DefaultCr0 = 0b10010111;
const uint8_t Cr0ReadMask = 0b10111101; // bits 1 and 6 auto clear, so ignore the value read
// CR1:
// Reserved=0
// AVGSEL=010 4 samples averaged, takes about 80ms
// TCTYPE=0011 K type thermocouple
const uint8_t DefaultCr1 = 0b00100000; // the thermocouple type needs to be or'd in
const uint8_t Cr1ReadMask = 0b01111111; // ignore the reserved bits
// MASK:
// reserved=00
// CJhigh = 1 don't assert fault on cold junction temperature high
// CJlow = 1 don't assert fault on cold junction temperature low
// TChigh = 1 don't assert fault on thermocouple temperature high
// TClow = 1 don't assert fault on thermocouple temperature low
// OV/UV=0 assert fault on under/over voltage
// Openfault=0 assert fault on open circuit condition
const uint8_t DefaultFaultMask = 0b00111100;
ThermocoupleSensor31856::ThermocoupleSensor31856(unsigned int sensorNum)
: SpiTemperatureSensor(sensorNum, "Thermocouple (MAX31856)", MAX31856_SpiMode, MAX31856_Frequency),
cr0(DefaultCr0), thermocoupleType(TypeK)
{
}
// Configure this temperature sensor
GCodeResult ThermocoupleSensor31856::Configure(GCodeBuffer& gb, const StringRef& reply)
{
bool seen = false;
if (!ConfigurePort(gb, reply, seen))
{
return GCodeResult::error;
}
TryConfigureSensorName(gb, seen);
if (gb.Seen('F'))
{
seen = true;
if (gb.GetIValue() == 60)
{
cr0 &= ~0x01; // set 60Hz rejection
}
else
{
cr0 |= 0x01; // default to 50Hz rejection
}
}
String<2> buf;
if (gb.TryGetQuotedString('K', buf.GetRef(), seen))
{
const char *p;
if (buf.strlen() == 1 && (p = strchr(TypeLetters, toupper(buf.c_str()[0]))) != nullptr)
{
thermocoupleType = p - TypeLetters;
}
else
{
reply.copy("Bad thermocouple type letter in M305 command");
return GCodeResult::error;
}
}
if (seen)
{
// Initialise the sensor
InitSpi();
TemperatureError rslt;
for (unsigned int i = 0; i < 3; ++i) // try 3 times
{
rslt = TryInitThermocouple();
if (rslt == TemperatureError::success)
{
break;
}
delay(MinimumReadInterval);
}
lastReadingTime = millis();
lastResult = rslt;
lastTemperature = 0.0;
if (rslt != TemperatureError::success)
{
reprap.GetPlatform().MessageF(ErrorMessage, "Failed to initialise thermocouple: %s\n", TemperatureErrorString(rslt));
}
}
else
{
CopyBasicDetails(reply);
reply.catf(", thermocouple type %c, reject %dHz", TypeLetters[thermocoupleType], (cr0 & 0x01) ? 50 : 60);
}
return GCodeResult::ok;
}
TemperatureError ThermocoupleSensor31856::TryInitThermocouple() const
{
const uint8_t modeData[4] = { 0x80, cr0, (uint8_t)(DefaultCr1 | thermocoupleType), DefaultFaultMask }; // write registers 0, 1, 2
uint32_t rawVal;
TemperatureError sts = DoSpiTransaction(modeData, ARRAY_SIZE(modeData), rawVal);
if (sts == TemperatureError::success)
{
static const uint8_t readData[4] = { 0x00, 0x00, 0x00, 0x00 }; // read registers 0, 1, 2
sts = DoSpiTransaction(readData, ARRAY_SIZE(readData), rawVal);
}
//debugPrintf("Status %d data %04x\n", (int)sts, rawVal);
if (sts == TemperatureError::success)
{
const uint32_t expectedResponseMask = (0b10111101 << 16) // bits 1 and 5 of CR0 auto-clear
| (0b01111111 << 8) // ignore the reserved bit
| (0b00111111); // ignore the reserved bits
if ((rawVal & expectedResponseMask) != (((modeData[1] << 16) | (modeData[2] << 8) | modeData[3]) & expectedResponseMask))
{
// debugPrintf("expected %08x got %08x\n", rawVal & expectedResponseMask, ((modeData[1] << 16) | (modeData[2] << 8) | modeData[3]) & expectedResponseMask);
sts = TemperatureError::badResponse;
}
}
return sts;
}
void ThermocoupleSensor31856::Poll()
{
static const uint8_t dataOut[5] = {0x0C, 0x55, 0x55, 0x55, 0x55}; // read registers LTCB0, LTCB1, LTCB2, Fault status
uint32_t rawVal;
TemperatureError sts = DoSpiTransaction(dataOut, ARRAY_SIZE(dataOut), rawVal);
if (sts != TemperatureError::success)
{
SetResult(sts);
}
else
{
lastReadingTime = millis();
if ((rawVal & 0x00FF) != 0)
{
// One or more fault bits is set
SetResult( (rawVal & 0x02) ? TemperatureError::overOrUnderVoltage
: (rawVal & 0x01) ? TemperatureError::openCircuit
: TemperatureError::hardwareError
);
delayMicroseconds(1); // MAX31856 requires CS to be high for 400ns minimum
TryInitThermocouple(); // clear fault bits and re-initialise
}
else
{
const int16_t rawTemp = (int16_t)(rawVal >> 16); // keep just the most significant 2 bytes and interpret them as signed
SetResult((float)rawTemp / 16, TemperatureError::success);
}
}
}
// End
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