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pounder stamper: overflow at u32 boundary

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This commit is contained in:
Robert Jördens 2021-02-04 15:42:29 +01:00
parent 473bdaa9bc
commit 2d492055f3
1 changed files with 4 additions and 14 deletions
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18
src/hardware/configuration.rs
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@ -759,23 +759,13 @@ pub fn setup(
// Pounder is configured to generate a 500MHz reference clock, so a 125MHz sync-clock is
// output. As a result, dividing the 125MHz sync-clk provides a 31.25MHz tick rate for
// the timestamp timer. 31.25MHz corresponds with a 32ns tick rate.
// This is less than fCK_INT/3 of the timer as required for oversampling the trigger.
timestamp_timer.set_external_clock(timers::Prescaler::Div4);
timestamp_timer.start();
// We want the pounder timestamp timer to overflow once per batch.
let tick_ratio = {
let sync_clk_mhz: f32 = design_parameters::DDS_SYSTEM_CLK.0
as f32
/ design_parameters::DDS_SYNC_CLK_DIV as f32;
sync_clk_mhz / design_parameters::TIMER_FREQUENCY.0 as f32
};
let period = (tick_ratio
* design_parameters::ADC_SAMPLE_TICKS as f32
* design_parameters::SAMPLE_BUFFER_SIZE as f32)
as u32
/ 4;
timestamp_timer.set_period_ticks((period - 1).try_into().unwrap());
// Set the timer to wrap at the u32 boundary to meet the PLL periodicity.
// Scale and wrap before or after the PLL.
timestamp_timer.set_period_ticks(u32::MAX);
let tim8_channels = timestamp_timer.channels();
pounder::timestamp::Timestamper::new(