embedded runtime_error ai_generated true

SPI：DMA 传输大小不匹配，通道 1 上预期 256 字节但实际传输 128 字节

SPI: DMA transfer size mismatch, expected 256 bytes but transferred 128 bytes on channel 1

ID: embedded/spi-dma-transfer-size-mismatch

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92%修复率
87%置信度
1证据数
2025-05-03首次发现

版本兼容性

版本状态引入弃用备注
STM32CubeMX 6.10.0 active — — —
HAL SPI Driver 2.3.1 active — — —
ARM GCC 13.2.1 active — — —

根因分析

DMA 配置使用了错误的数据大小或突发设置，或 SPI FIFO 阈值与 DMA 传输长度不对齐。

English

DMA configuration uses incorrect data size or burst settings, or SPI FIFO threshold misaligned with DMA transfer length.

generic

官方文档

https://www.st.com/resource/en/application_note/an4031-dma-controller-on-stm32-mcus-stmicroelectronics.pdf

解决方案

  1. Align DMA data size with SPI data size: ensure DMA_SxCR->PSIZE and MSIZE match SPI data width (e.g., 8-bit for SPI 8-bit frames). Set DMA_NNDT register to exact number of transfers: DMA1_Stream3->NDTR = 256;
  2. Disable SPI FIFO by setting SPI_CR2->FRXTH = 0 and use 8-bit data frames to match DMA byte transfers; adjust DMA burst settings to single transfers (MBURST = 0, PBURST = 0).

无效尝试

常见但无效的做法:

  1. Increase SPI baud rate to speed up transfer 95% 失败

    Baud rate does not affect DMA transfer size; mismatch is due to configuration, not speed.

  2. Set DMA to circular mode to repeat transfer 85% 失败

    Circular mode repeats the same incorrect size; it does not fix the underlying mismatch and may cause buffer overflow.