Echelon Mini FX - Manual (Page 104)

Mini FX User's Guide 91
Thermostat();
}
when(timer_expires(sampleTimer)) {
Thermostat();
}
when(nv_update_occurs(nviSetpoint)) {
Thermostat();
}
void OnButtonPressed(void)
{
// do nothing in this application
}
The Thermostat() function then implements the behavior of the functional block:
//
// The Thermostat function samples the current temperature,
// computes the control values for heater and cooler, and
// updates the status network variable as it goes along.
// Current and setpoint values are being displayed, and the
// next sample is scheduled.
//
// Thermostat() uses the Display() utility function.
//
void Display(unsigned row, unsigned column,
const char* format, SNVT_temp_p value);
void Thermostat(void)
{
SNVT_temp_p reading;
// Get the true current temperature
reading = GetTemperature();
// Discard current reading and use previous value, if new
// reading is still within hysteresis band:
if (nciHysteresis == 0
|| reading < nvoCurrent-nciHysteresis
|| reading > nvoCurrent+nciHysteresis) {
nvoCurrent = reading;
} else {
// refresh output network variable for re-propagation
// (heartbeat)
nvoCurrent = nvoCurrent;
}
// compute cooler and heater control values
if (nvoCurrent < nviSetpoint) {
nvoCool = 0;
nvoHeat = nvoUnitStatus.heat_output_primary =
muldiv(nviSetpoint-nvoCurrent,
nciHeatFactor.multiplier,
nciHeatFactor.divisor);
nvoUnitStatus.mode = HVAC_HEAT;
}
if (nvoCurrent > nviSetpoint) {
nvoHeat = 0;
nvoCool = nvoUnitStatus.cool_output =
muldiv(nvoCurrent-nviSetpoint,
nciCoolFactor.multiplier,
nciCoolFactor.divisor);
nvoUnitStatus.mode = HVAC_COOL;
}
// Indicate heat/cool status and drive value display
SetLeds((boolean)nvoCool, (boolean)nvoHeat);
Display(2,0, "Current: 0.00", nvoCurrent);