Скачать или смотреть Resolving I2C Transmit Issues with DMA on STM32

Struggling to transmit data via I2C using DMA in your STM32 project? Discover effective solutions and detailed troubleshooting steps in this comprehensive guide.
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Resolving I2C Transmit Issues with DMA on STM32: A Comprehensive Guide

If you're working with an STM32 microcontroller and have faced challenges in transmitting data via I2C using Direct Memory Access (DMA), you're not alone. Many developers encounter similar issues, especially when attempting to send large buffers—like a full image—through I2C. This guide will guide you through the common problems, such as finishing DMA transfers while I2C is still operating, and offer solid solutions to get your data transmitting smoothly.

Understanding the Problem

When attempting to send a sizable 1024-byte buffer to an SSD1306 display using I2C and DMA, you might find that not all data sends successfully—often only the first 254 bytes get transferred. Below is a brief recap of the challenge:

Common Symptoms

Data transmission halts unexpectedly after transferring a portion of the data.

Expected output on the display does not align with the transmitted data.

In your specific case, using the HAL (Hardware Abstraction Layer) specifically generated in STM32CubeIDE for managing I2C and DMA becomes complex due to interrupt handling and the configuration required to support larger data buffers.

Step-by-Step Solution

1. Modify Interrupt Handlers

Your custom interrupt handlers (DMA1_Channel6_IRQHandler and I2C1_EV_IRQHandler) should be simplified. Remove unnecessary user-defined code since the HAL provides the necessary routines to manage these interrupts effectively.

2. Enable I2C Event Interrupts

Make sure to enable the I2C event interrupts in your STM32 Device Configuration Tool. This step is crucial for seamless data transmission.

3. Configure DMA Properly

Configure the DMA settings for your I2C transaction. Ensure that the data width is set correctly to byte/byte. This configuration allows for the transmission of each byte of data correctly over the I2C bus.

4. Use HAL Functions for DMA Transmission

Instead of manually handling DMA transfer commands, use HAL's built-in functions to initiate the I2C transmission. Here's a snippet of what the function might look like:

[[See Video to Reveal this Text or Code Snippet]]

5. Check for HAL State Before Each Transfer

Before sending another transmission, always check that HAL_I2C_STATE_READY is achieved. This practice avoids starting a new transmission before the previous has completed.

Understanding HAL's Internal Management

There's a clear distinction in how HAL manages I2C + DMA interactions. It effectively sends data in chunks—usually of 255 bytes—while handling interrupts for complete, pending, or error states automatically. This feature is where the built-in HAL functionality shines, so it's worthwhile to delve into the source code:

I2C_DMAMasterTransmitCplt: Handles the complete callback for DMA transfers.

I2C_Master_ISR_DMA: Resets parameters for subsequent transfers and ensures proper transfer configuration.

Working with Larger Buffers Using HAL

For transmitting larger datasets like your 1024-byte buffer, each transmission needs to respect the 255-byte limit inherently dictated by the I2C specifications. The HAL abstracts this complexity away through appropriate calls and settings that you need to trigger correctly. In advanced implementations, circular DMA mode can be leveraged for high frame rates—though note that this setup might require more intricate adjustments.

Example of Circular DMA Setup

Here is a brief code demonstration:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

When dealing with I2C and DMA on the STM32 platform, relying on HAL's capabilities ensures that you adhere to best practices and robust settings without unnecessary complexity. By simplifying your code and letting HAL manag