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Code Issues Releases Wiki Activity

Support MAX31855 as Temperature Sensor -3

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This commit is contained in:
Scott Lahteine 2016-03-08 06:58:11 -08:00
parent bedd4dab6a
commit 27f244ba2c
24 changed files with 76 additions and 51 deletions

59
Marlin/temperature.cpp
View file

@ -1145,21 +1145,31 @@ void disable_all_heaters() {
}
#if ENABLED(HEATER_0_USES_MAX6675)
#define MAX6675_HEAT_INTERVAL 250u
#if ENABLED(MAX6675_IS_MAX31855)
unsigned long max6675_temp = 2000;
#define MAX6675_READ_BYTES 4
#define MAX6675_ERROR_MASK 7
#define MAX6675_DISCARD_BITS 18
#else
unsigned int max6675_temp = 2000;
#define MAX6675_READ_BYTES 2
#define MAX6675_ERROR_MASK 4
#define MAX6675_DISCARD_BITS 3
#endif
static millis_t next_max6675_ms = 0;
int max6675_temp = 2000;
static int read_max6675() {
millis_t ms = millis();
if (ms < next_max6675_ms)
return max6675_temp;
if (ms < next_max6675_ms) return (int)max6675_temp;
next_max6675_ms = ms + MAX6675_HEAT_INTERVAL;
max6675_temp = 0;
CBI(
#ifdef PRR
PRR
@ -1169,36 +1179,29 @@ void disable_all_heaters() {
, PRSPI);
SPCR = _BV(MSTR) | _BV(SPE) | _BV(SPR0);
// enable TT_MAX6675
WRITE(MAX6675_SS, 0);
WRITE(MAX6675_SS, 0); // enable TT_MAX6675
// ensure 100ns delay - a bit extra is fine
asm("nop");//50ns on 20Mhz, 62.5ns on 16Mhz
asm("nop");//50ns on 20Mhz, 62.5ns on 16Mhz
// read MSB
SPDR = 0;
for (; !TEST(SPSR, SPIF););
max6675_temp = SPDR;
max6675_temp <<= 8;
// read LSB
SPDR = 0;
for (; !TEST(SPSR, SPIF););
max6675_temp |= SPDR;
// disable TT_MAX6675
WRITE(MAX6675_SS, 1);
if (max6675_temp & 4) {
// thermocouple open
max6675_temp = 4000;
}
else {
max6675_temp = max6675_temp >> 3;
// Read a big-endian temperature value
max6675_temp = 0;
for (uint8_t i = MAX6675_READ_BYTES; i--;) {
SPDR = 0;
for (;!TEST(SPSR, SPIF););
max6675_temp |= SPDR;
if (i > 0) max6675_temp <<= 8; // shift left if not the last byte
}
return max6675_temp;
WRITE(MAX6675_SS, 1); // disable TT_MAX6675
if (max6675_temp & MAX6675_ERROR_MASK)
max6675_temp = 4000; // thermocouple open
else
max6675_temp >>= MAX6675_DISCARD_BITS;
return (int)max6675_temp;
}
#endif //HEATER_0_USES_MAX6675