topic Re: S32K312 uart AsyncReceive callback event is always error when SPI DMA transfer mass data in S32K

S32K312 uart AsyncReceive callback event is always error when SPI DMA transfer mass data

gan89557 — Sat, 13 Dec 2025 14:57:18 GMT

Hello,

S32K312 S32DS3.5 RTD4.0.0 project, SPI0 and SPI1 work with DMA mode, and UART1 work with Interrupt mode.

UART1 work well when sync send or async receive a frame of 12 bytes.

But uart AsyncReceive callback event is always error when SPI DMA transfer mass data.

Any suggestion?

Re: S32K312 uart AsyncReceive callback event is always error when SPI DMA transfer mass data

PetrS — Mon, 15 Dec 2025 10:28:50 GMT

Hi,

there can be below possible reasons for UART Async Receive Errors during SPI DMA bursts:

1. Interrupt Priority Issue

- UART RX interrupt is not serviced quickly because DMA completion or other ISRs have equal or higher priority.
- Result: UART RX FIFO overflows → overrun or framing error.

Ensure LPUART1_IRQn has higher priority (numerically lower) than all DMA-related IRQs (e.g., DMATCDx_IRQn). Confirm interrupt grouping allows preemption.

2. Bus Occupation by DMA

- eDMA channels for SPI can saturate the AXBS crossbar during large bursts.
- CPU and peripheral register accesses (including UART RX handling) are delayed, increasing ISR latency.

Configure SPI DMA channels to allow eDMA engine stalls (BWC setting)

BR, Petr

Re: S32K312 uart AsyncReceive callback event is always error when SPI DMA transfer mass data

gan89557 — Mon, 15 Dec 2025 13:18:17 GMT

Yes, It is the Interrupt Priority Issue, Uart1 works after Raising it's Priority.

Thanks so much!