RE: Connecting LPCOMP CROSS event to TWO DPPI-driven tasks (GPIOTE toggle + TIMER count) simultaneously — only the last-configured one fires

Kenneth — Thu, 02 Jul 2026 12:48:39 GMT

Hello,

Question 1: Can one event publish to multiple DPPI channels?
No. The datasheet explicitly states "One publish register per event," and the PUBLISH register has a single CHIDX field. This means Approach A cannot work by design, writing to the same event's publish register a second time overwrites the first channel assignment, which is what you observed.

Question 2: Why Didn't Approach B Work?
Approach B should work in theory (one channel with multiple task subscriptions), but it failed likely because:

Domain mismatch not handled - LPCOMP publishes on DPPIC30; GPIOTE/TIMER subscribe on DPPIC20
Missing PPIB configuration - No bridge was set up between the domains
Errata [26] workaround not applied - For nRF54L15 Rev 1 and 2, the PPIB channel number must match the DPPIC channel index (e.g., use PPIB channel 0 with DPPIC channel 0) https://docs.nordicsemi.com/r/bundle/errata_nrf54l15_rev2/page/err/nrf54l15/rev2/latest/anomaly_l15_26.html

Question 3: Is there a DPPI domain mismatch?
Likely wes. Looking at the instantiation table:

Peripheral Domain DPPIC

LPCOMP LP DPPIC30 (4 channels)

GPIOTE20 PERI DPPIC20 (16 channels)

TIMER20/21 PERI DPPIC20 (16 channels)

LPCOMP is in the LP power domain with DPPIC30, while GPIOTE20 and TIMER20/21 are in the PERI power domain with DPPIC20. These domains cannot communicate directly via DPPI.

Use PPIB (PPI Bridge) to Cross Domains. To connect LPCOMP -> GPIOTE20/TIMER20, you must bridge the LP domain to the PERI domain using PPIB30 -> PPIB22 (per the Figure 23: Power domains and PPI bridges in datasheet).

Hope that helps,
Kenneth