diff options
Diffstat (limited to 'center_fw/adc.c')
| -rw-r--r-- | center_fw/adc.c | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/center_fw/adc.c b/center_fw/adc.c index 0fb8251..d702274 100644 --- a/center_fw/adc.c +++ b/center_fw/adc.c @@ -77,8 +77,11 @@ void adc_configure_scope_mode(uint8_t channel_mask, int sampling_interval_ns) { adc_timer_init(12/*250ns/tick*/, cycles); } -/* Regular operation receiver mode */ -void adc_configure_monitor_mode(const struct command_if_def *cmd_if, int ivl_us) { +/* FIXME figure out the proper place to configure this. */ +#define ADC_TIMER_INTERVAL_US 20 + +/* Regular operation receiver mode. */ +void adc_configure_monitor_mode(const struct command_if_def *cmd_if) { /* First, disable trigger timer, DMA and ADC in case we're reconfiguring on the fly. */ TIM1->CR1 &= ~TIM_CR1_CEN; ADC1->CR &= ~ADC_CR_ADSTART; @@ -93,7 +96,8 @@ void adc_configure_monitor_mode(const struct command_if_def *cmd_if, int ivl_us) st.mean_aggregate_ctr = 0; st.det_st.hysteresis_mv = 6000; - st.det_st.base_interval_cycles = 10; + /* base_cycles * the ADC timer interval (20us) must match the driver's AC period. */ + st.det_st.base_interval_cycles = 40; /* 40 * 20us = 800us/1.25kHz */ st.det_st.sync = 0; st.det_st.last_bit = 0; @@ -121,7 +125,12 @@ void adc_configure_monitor_mode(const struct command_if_def *cmd_if, int ivl_us) ADC1->CR |= ADC_CR_ADEN; ADC1->CR |= ADC_CR_ADSTART; - adc_timer_init(SystemCoreClock/1000000/*1.0us/tick*/, ivl_us); + /* Initialize the timer. Set the divider to get a nice round microsecond tick. The interval must be long enough to + * comfortably fit all conversions inside. There should be some margin since the ADC runs off its own internal RC + * oscillator and will drift w.r.t. the system clock. 20us is a nice value when four channels are selected (A, B, + * T and V). + */ + adc_timer_init(SystemCoreClock/1000000/*1.0us/tick*/, 20/* us */); } static void adc_dma_init(int burstlen, bool enable_interrupt) { @@ -189,7 +198,7 @@ void receive_bit(struct bit_detector_st *st, int bit) { receive_symbol(&st->rx_st, symbol); GPIOA->BRR = 1<<9; /* debug */ - /* Debug scope logic */ + /* Exceedingly handy piece of debug code: The Debug Scope 2000 (TM) */ /* static int debug_buf_pos = 0; if (st->sync) { |