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temp.c: integrate next_start_adc_time clock into next_read_time. 

Extra clock next_start_adc_time was unnecessary. As @phord
observed, it was more understandable to explicitly call start_adc()
1 cycle ahead during temp_sensor_tick(), for sensors which use
analog_read().
This commit is contained in:
Robert Konklewski 2016-04-22 20:55:00 +02:00 committed by Markus Hitter
parent 1aa8698f62
commit 86c3d97315
1 changed files with 39 additions and 38 deletions
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77
temp.c
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@ -89,15 +89,6 @@ struct {
uint16_t next_read_time; ///< how long until we can read this sensor again?
} temp_sensors_runtime[NUM_TEMP_SENSORS];
#ifdef NEEDS_START_ADC
/**
Timer/counter for initiating ADC reads via start_adc(). Runs on the same
interval as analog_read(), but is shifted in time, which is why this
additional counter is needed.
*/
uint16_t next_start_adc_time;
#endif
/** \def TEMP_EWMA
Default alpha constant for the Exponentially Weighted Moving Average (EWMA)
@ -141,16 +132,18 @@ void temp_init() {
#ifdef TEMP_THERMISTOR
// Mostly handled by analog_init().
case TT_THERMISTOR:
// Schedule first read.
temp_sensors_runtime[i].next_read_time = ANALOG_READ_INTERVAL;
// Schedule first read. Decrement by 1, because clock_counter_250ms
// is 1 tick ahead.
temp_sensors_runtime[i].next_read_time = ANALOG_READ_INTERVAL - 1;
break;
#endif
#ifdef TEMP_AD595
// Mostly handled by analog_init().
case TT_AD595:
// Schedule first read.
temp_sensors_runtime[i].next_read_time = ANALOG_READ_INTERVAL;
// Schedule first read. Decrement by 1, because clock_counter_250ms
// is 1 tick ahead.
temp_sensors_runtime[i].next_read_time = ANALOG_READ_INTERVAL - 1;
break;
#endif
@ -171,16 +164,6 @@ void temp_init() {
break;
}
}
#ifdef NEEDS_START_ADC
/**
Schedule the first ADC conversion so that it starts one 10ms cycle
before the sensors are actually read. This way analog_read() returns a
value that's only 10ms old.
*/
next_start_adc_time = (ANALOG_READ_INTERVAL > 0) ?
(ANALOG_READ_INTERVAL - 1) : 0;
#endif
}
/**
@ -419,6 +402,39 @@ void temp_sensor_tick() {
) / EWMA_SCALE);
}
#ifdef NEEDS_START_ADC
/**
Sensors that use analog_read() need an start_adc() a 10ms cycle before
they actually do the reading so that ADC conversion can start and
finish in time.
*/
if (temp_sensors_runtime[i].next_read_time == 1) {
uint8_t needs_start_adc = 0;
// Determine if the sensor uses analog_read().
switch(temp_sensors[i].temp_type) {
#ifdef TEMP_THERMISTOR
case TT_THERMISTOR:
needs_start_adc = 1;
break;
#endif
#ifdef TEMP_AD595
case TT_AD595:
needs_start_adc = 1;
break;
#endif
default: /* Prevent compiler warning. */
break;
}
if (needs_start_adc) {
start_adc();
}
}
#endif
/**
Decrement the counter here so that we avoid a off-by-one error. It's
assumed that sensor update code in the switch statement above has set a
@ -426,21 +442,6 @@ void temp_sensor_tick() {
*/
temp_sensors_runtime[i].next_read_time--;
}
#ifdef NEEDS_START_ADC
// Start ADC conversion when the time comes.
if (next_start_adc_time > 1) {
next_start_adc_time--;
} else {
start_adc();
/**
start_adc() runs on the same interval as analog_read(), but it's
shifted in time so that it happens 10ms earlier. This way the ADC
conversion can finish before its results are read.
*/
next_start_adc_time = ANALOG_READ_INTERVAL;
}
#endif
}
/**