diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/avr32dd20.c | 60 | ||||
| -rw-r--r-- | arch/avr32dd20.h | 15 |
2 files changed, 46 insertions, 29 deletions
diff --git a/arch/avr32dd20.c b/arch/avr32dd20.c index 45923a8..998e9f6 100644 --- a/arch/avr32dd20.c +++ b/arch/avr32dd20.c @@ -52,19 +52,19 @@ inline void mcu_set_admux_therm() { ADC0.SAMPCTRL = 32; // set single-ended or differential // set resolution to 12 bits - // set left- or right-adjust (right) + // set left- or right-adjust // set free-running mode or not (yes) ADC0.CTRLA = ADC_CONVMODE_SINGLEENDED_gc | ADC_RESSEL_12BIT_gc - //| ADC_LEFTADJ_bm // not in temperature mode + | ADC_LEFTADJ_bm | ADC_FREERUN_bm; // set number of samples (requires adjustment in formula too) ADC0.CTRLB = ADC_SAMPNUM_NONE_gc; - // TODO: accumulate more samples for more resolution - // (and probably set the prescale faster too) - //ADC0.CTRLB = ADC_SAMPNUM_ACC16_gc; // 16 samples per result + // accumulate more samples for more resolution + ADC0.CTRLB = ADC_SAMPNUM_ACC16_gc; // 16 samples per result // set a clock prescaler - ADC0.CTRLC = ADC_PRESC_DIV64_gc; + //ADC0.CTRLC = ADC_PRESC_DIV64_gc; // use this when no accumulation + ADC0.CTRLC = ADC_PRESC_DIV4_gc; // measure faster when oversampling // enable the ADC ADC0.CTRLA |= ADC_ENABLE_bm; // actually start measuring (happens in another function) @@ -90,7 +90,7 @@ inline void mcu_set_admux_voltage() { // set number of samples ADC0.CTRLB = ADC_SAMPNUM_ACC16_gc; // 16 samples per result // set a clock prescaler - ADC0.CTRLC = ADC_PRESC_DIV16_gc; // not too fast, not too slow + ADC0.CTRLC = ADC_PRESC_DIV4_gc; // measure faster when oversampling // select the positive ADC input with MUXPOS #ifdef USE_VOLTAGE_DIVIDER // external voltage divider // ADC input pin / Vref @@ -113,11 +113,8 @@ inline void mcu_adc_sleep_mode() { } inline void mcu_adc_start_measurement() { - // FIXME: enable this after getting ADC stuff fixed - #if 0 ADC0.INTCTRL |= ADC_RESRDY_bm; // enable interrupt ADC0.COMMAND |= ADC_STCONV_bm; // actually start measuring - #endif } /* @@ -135,24 +132,35 @@ inline void mcu_adc_vect_clear() { ADC0.INTFLAGS = ADC_RESRDY_bm; // clear the interrupt } -inline uint16_t mcu_adc_result_temp() { - // FIXME: better math, higher precision - // Use the factory calibrated values in SIGROW.TEMPSENSE0 and - // SIGROW.TEMPSENSE1 to calculate a temperature reading in Kelvin, then - // left-align it. - int8_t sigrow_offset = SIGROW.TEMPSENSE1; // Read signed value from signature row - uint8_t sigrow_gain = SIGROW.TEMPSENSE0; // Read unsigned value from signature row - uint32_t temp = ADC0.RES - sigrow_offset; - temp *= sigrow_gain; // Result might overflow 16 bit variable (10bit+8bit) - temp += 0x80; // Add 1/2 to get correct rounding on division below - //temp >>= 8; // Divide result to get Kelvin - //return temp << 6; // left align it - return temp >> 2; // left-aligned uint16_t +inline uint16_t mcu_adc_result() { + // value is 12-bit left-aligned + 16x oversampling = 16 bits total + return ADC0.RES; } -inline uint16_t mcu_adc_result_volts() { - // voltage is 12-bit right-aligned + 16x oversampling = 16 bits total - return ADC0.RES; +inline uint16_t mcu_vdd_raw2cooked(uint16_t measurement) { + // In : 65535 * (Vbat / 10) / 1.024V + // Out: 65535 * (Vbat / 10) / 1.024V + // This MCU's native format is already correct + return measurement; +} + +inline uint16_t mcu_temp_raw2cooked(uint16_t measurement) { + // convert raw ADC values to calibrated temperature + // In: ADC raw temperature (16-bit, or 12-bit left-aligned) + // Out: Kelvin << 6 + // Precision: 1/64th Kelvin (but noisy) + // AVR DD datasheet section 33.3.3.8 + uint16_t sigrow_slope = SIGROW.TEMPSENSE0; // factory calibration data + uint16_t sigrow_offset = SIGROW.TEMPSENSE1; // 12-bit value + //const uint32_t scaling_factor = 4096; // use top 12 bits of ADC data + //uint32_t temp = sigrow_offset - (measurement >> 4); + const uint32_t scaling_factor = 65536; // use all 16 bits of ADC data + uint32_t temp = (sigrow_offset << 4) - measurement; + temp *= sigrow_slope; // 24-bit result + temp += scaling_factor / 8; // Add 1/8th K to get correct rounding on later divisions + //temp = temp >> 6; // change (K << 12) to (K << 6) + temp = temp >> 10; // change (K << 16) to (K << 6) + return temp; // left-aligned uint16_t, 0 to 1023.98 Kelvin } inline uint8_t mcu_adc_lsb() { diff --git a/arch/avr32dd20.h b/arch/avr32dd20.h index 7a6b8f1..3ebb05a 100644 --- a/arch/avr32dd20.h +++ b/arch/avr32dd20.h @@ -50,12 +50,21 @@ inline void mcu_adc_off(); #define ADC_vect ADC0_RESRDY_vect inline void mcu_adc_vect_clear(); +// both readings are left-aligned +inline uint16_t mcu_adc_result(); + // read ADC differently for temperature and voltage -#define MCU_ADC_RESULT_PER_TYPE +//#define MCU_ADC_RESULT_PER_TYPE +//inline uint16_t mcu_adc_result_temp(); +//inline uint16_t mcu_adc_result_volts(); -inline uint16_t mcu_adc_result_temp(); +// return (centiVolts << 6), range 0 to 10.24V +#define voltage_raw2cooked mcu_vdd_raw2cooked +inline uint16_t mcu_vdd_raw2cooked(uint16_t measurement); -inline uint16_t mcu_adc_result_volts(); +// return (temp in Kelvin << 6) +#define temp_raw2cooked mcu_temp_raw2cooked +inline uint16_t mcu_temp_raw2cooked(uint16_t measurement); inline uint8_t mcu_adc_lsb(); |