arch/arm/src/stm32h7/stm32_fdcan_sock: fix clock, ILS register and ID#18300
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vrmay23 wants to merge 1 commit intoapache:masterfrom
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arch/arm/src/stm32h7/stm32_fdcan_sock: fix clock, ILS register and ID#18300vrmay23 wants to merge 1 commit intoapache:masterfrom
vrmay23 wants to merge 1 commit intoapache:masterfrom
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Feb 2, 2026
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I think it is correct now. Could you please check it again? Thank you! |
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@xiaoxiang781216 I have finished the reviews. Thanks for feedback! |
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Fix three issues in the STM32H7 FDCAN SocketCAN driver: 1. Clock configuration: Allow board.h to override STM32_FDCANCLK. Previously the driver hardcoded STM32_HSE_FREQUENCY, ignoring any board-specific clock configuration. 2. ILS register bug: Fix putreg32 call that was writing FDCAN_ILS_TCL constant instead of the computed regval, causing interrupt routing issues. 3. Extended ID filter size: Increase n_extid from 64 to 128. Despite the reference manual (RM0433) suggesting 64 max, testing shows that 128 is required for reliable extended ID frame reception. With 64, some extended ID frames were silently dropped. Signed-off-by: Vinicius May <vmay.sweden@gmail.com>
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Starting up: 
candump (500kpbs 1 msg per 10 ms): 
cansend (I have created an 'canflood app' to test NuttX SocketCAN transmission power, later on I'll also submit this PR): 
I'm wonder if it is needed a long stress test. If needed just tell me how to provide it. |
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fix clock, ILS register and ID (extended).
Fix three issues in the STM32H7 FDCAN SocketCAN driver:
Clock configuration: Allow board.h to override STM32_FDCANCLK. Previously the driver hardcoded STM32_HSE_FREQUENCY, ignoring any board-specific clock configuration.
ILS register bug: Fix putreg32 call that was writing FDCAN_ILS_TCL constant instead of the computed regval, causing interrupt routing issues.
Extended ID filter size: Increase n_extid from 64 to 128. Despite the reference manual (RM0433) suggesting 64 max, testing shows that 128 is required for reliable extended ID frame reception. With 64, some extended ID frames were silently dropped.
Note: Please adhere to Contributing Guidelines.
Summary
Fix three critical bugs in the STM32H7 FDCAN SocketCAN driver:
Clock configuration: Allow board.h to override STM32_FDCANCLK. Previously the driver hardcoded STM32_HSE_FREQUENCY, ignoring board-specific clock configurations. This causes incorrect bit timing on boards that use PLL-derived clocks instead of HSE.
ILS register bug: Fix putreg32 call writing FDCAN_ILS_TCL constant instead of the computed regval variable. This is a read-modify-write bug that zeroes other ILS register bits and breaks interrupt routing.
Extended ID filter size: Increase n_extid from 64 to 128. Testing shows the STM32H7 hardware supports 128 filters despite ambiguous documentation. With 64 filters, extended ID frames are silently dropped under load.
Impact
Improves driver reliability and portability. Users with non-HSE FDCAN clocks or heavy extended ID usage will see immediate improvements. Backward compatible with existing configurations.
Testing
Hardware: STM32 Nucleo-H753ZI + external CAN transceiver TJA1051T and TJA1050T.
Peer: Linux PC with PEAK USB-FD adapter
Config: nucleo-h753zi:evaluation
Tools: candump, cansend