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# File 'ext/max31855/max31855.c', line 86
VALUE wMax31855_fetch(VALUE self)
{
struct spidev *device;
unsigned char* recv;
unsigned int thermocouple_raw;
unsigned int internal_raw;
double thermocouple, internal;
Data_Get_Struct(self, struct spidev, device);
recv = receiveData(device, 4);
thermocouple_raw = recv[0] << 8;
thermocouple_raw |= recv[1];
internal_raw = recv[2] << 8;
internal_raw |= recv[3];
if (thermocouple_raw & 0x0001) { // On error
char message[128];
memset(message, 0, 128);
if (internal_raw & 0x0004)
strcat(message, "Short to Vcc,");
if (internal_raw & 0x0002)
strcat(message, "Short to GND,");
if (internal_raw & 0x0001)
strcat(message, "Open Circuit");
rb_raise(rb_eStandardError, "Sensor error: %s", message);
return Qnil;
} else {
if ((thermocouple_raw & 0x8000) == 0) // above 0 Degrees Celsius
thermocouple = (thermocouple_raw >> 2) * 0.25;
else // below zero
thermocouple = (((~thermocouple_raw & 0xffff) >> 2) + 1) * -0.25;
if ((internal_raw & 0x8000) == 0) // above 0 Degrees Celsius
internal = (internal_raw >> 4) * 0.0625;
else // below zero
internal = (((~internal_raw & 0xffff) >> 4) + 1) * -0.0625;
return rb_ary_new3(2, rb_float_new(thermocouple), rb_float_new(internal));
}
}
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