diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/ao_adc.c | 12 | ||||
| -rw-r--r-- | src/ao_convert.c | 10 |
2 files changed, 16 insertions, 6 deletions
diff --git a/src/ao_adc.c b/src/ao_adc.c index b0bfceb1..2b972e6c 100644 --- a/src/ao_adc.c +++ b/src/ao_adc.c @@ -46,16 +46,18 @@ ao_adc_isr(void) interrupt 1 uint8_t __xdata *a; sequence = (ADCCON2 & ADCCON2_SCH_MASK) >> ADCCON2_SCH_SHIFT; + if (sequence == ADCCON3_ECH_TEMP) + sequence = 2; a = (uint8_t __xdata *) (&ao_adc_ring[ao_adc_head].accel + sequence); a[0] = ADCL; a[1] = ADCH; if (sequence < 5) { /* start next channel conversion */ - sequence++; - /* skip channel 2, we don't have a temp sensor on v0.2 */ - if (sequence == 2) - sequence++; - ADCCON3 = ADCCON3_EREF_VDD | ADCCON3_EDIV_512 | sequence; + /* v0.2 replaces external temp sensor with internal one */ + if (sequence == 1) + ADCCON3 = ADCCON3_EREF_1_25 | ADCCON3_EDIV_512 | ADCCON3_ECH_TEMP; + else + ADCCON3 = ADCCON3_EREF_VDD | ADCCON3_EDIV_512 | (sequence + 1); } else { /* record this conversion series */ ao_adc_ring[ao_adc_head].tick = ao_time(); diff --git a/src/ao_convert.c b/src/ao_convert.c index 57ed7370..f29ce9e9 100644 --- a/src/ao_convert.c +++ b/src/ao_convert.c @@ -49,7 +49,15 @@ ao_temp_to_dC(int16_t temp) __reentrant int16_t ret; ao_mutex_get(&ao_temp_mutex); - ret = (int16_t) ((temp >> 4) * 3300L / 2047L) - 500; + /* Output voltage at 0°C = 0.755V + * Coefficient = 0.00247V/°C + * Reference voltage = 1.25V + * + * temp = ((value / 32767) * 1.25 - 0.755) / 0.00247 + * = (value - 19791.268) / 32768 * 1.25 / 0.00247 + * ≃ (value - 19791) * 1012 / 65536 + */ + ret = ((temp - 19791) * 1012L) >> 16; ao_mutex_put(&ao_temp_mutex); return ret; } |