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The SAADC internal sample timer only works with a single enabled channel, so hardware-timed multi-channel scan was not possible. Add NRF52_SAADC_TIMER_PPI, a third trigger mode in which a general-purpose TIMER compare event is routed to TASKS_SAMPLE over PPI. All enabled channels are scanned, and the TIMER prescaler allows much lower sample rates than the internal timer, which is limited to 16MHz/CC with CC in 80..2047. NRF52_SAADC_CONTINUOUS is no longer tied to the internal timer and works with either source. Its EasyDMA buffers now hold NRF52_SAADC_CONTINUOUS_BUFLEN whole scans rather than that many single samples, so MAXCNT becomes chan_len * BUFLEN. Samples are interleaved scan by scan, so a channel map is built once at configure() time and passed to the upper half with the batch; the upper half already accepts a per-sample channel array. A single-channel configuration produces the same MAXCNT and the same delivery as before. Because both features want a PPI channel, add a build-time check that NRF52_SAADC_PPI_CHANNEL and NRF52_SAADC_CONTINUOUS_PPI_CH differ, and constrain the latter under the SoftDevice controller like the former. NRF52_SAADC_CHANNELS gains a default and range for the new mode, and documents that the internal timer is restricted to one channel. Assisted-by: Claude Code Signed-off-by: raiden00pl <raiden00@railab.me> |
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