Why STM32F429NIH6 is Not Writing to Flash Memory : Common Issues

Why STM32F429NIH6 is Not Writing to Flash Memory: Common Issues and Solutions

The STM32F429NIH6 microcontroller is a Power ful device commonly used in embedded systems, but sometimes developers encounter issues when trying to write to its flash memory. Here’s a detailed analysis of the common causes and step-by-step solutions to help you troubleshoot and resolve this problem.

1. Flash Memory Write Protection

Cause: One of the most common reasons STM32F429NIH6 may not write to flash memory is due to flash write protection. The microcontroller has a built-in write protection mechanism that prevents accidental overwriting of flash memory.

Solution:

Check the Flash Write Protection: The STM32F429NIH6 allows for certain sectors of flash memory to be write-protected. Ensure the relevant flash memory sectors are not write-protected. This can be checked via the Flash Option Bytes. Disable Write Protection: To disable write protection, you can modify the Option Bytes through the STM32CubeProgrammer tool or directly in code. Example code to disable write protection: c FLASH_OB_Unlock(); // Unlock Option Bytes FLASH_OB_RDPLevelConfig(FLASH_OB_RDP_Level_0); // Set Read-Out Protection to Level 0 FLASH_OB_WRPConfig(FLASH_OB_WRP_Sector_All, DISABLE); // Disable write protection on all sectors FLASH_OB_Launch(); // Commit the changes Reboot the MCU to apply the new configuration. 2. Flash Memory Erasure

Cause: STM32 flash memory must be erased before writing new data to it. If a flash sector is not erased, writing to that sector can fail.

Solution:

Erase the Flash Memory Sectors:

Use the HALFLASHErase function to erase the sector before writing to it. If you’re using an STM32CubeMX-generated HAL project, you can implement the following in your code:

FLASH_EraseInitTypeDef EraseInitStruct; uint32_t SectorError; EraseInitStruct.TypeErase = FLASH_TYPEERASE_SECTORS; EraseInitStruct.Sector = FLASH_SECTOR_3; // Specify the sector to erase EraseInitStruct.NbSectors = 1; EraseInitStruct.VoltageRange = FLASH_VOLTAGE_RANGE_3; if (HAL_FLASH_Unlock() == HAL_OK) { if (HAL_FLASHEx_Erase(&EraseInitStruct, &SectorError) != HAL_OK) { // Handle erase error } HAL_FLASH_Lock(); // Lock the flash again after erasing }

Verify Erasure: You can verify that the sector is erased by reading back the flash and ensuring that the data is set to 0xFF (erased state).

3. Incorrect Voltage Supply or Power Issues

Cause: Writing to flash memory requires a stable voltage supply. If the MCU is not receiving adequate voltage or if the power supply is unstable, writing to flash memory will fail.

Solution:

Check Power Supply: Ensure that the STM32F429NIH6 is receiving a stable 3.3V (or appropriate voltage as per the datasheet) at all times, especially during write operations. Verify Power Stability: If using a battery or an external power supply, make sure it is capable of delivering consistent power during flash operations. 4. Flash Programming Algorithm Issues

Cause: The STM32F429NIH6 uses specific programming algorithms to write to flash memory. Incorrect configuration or improper use of these algorithms may prevent successful writes.

Solution:

Use Correct Programming Sequence: Flash programming involves unlocking the flash, performing the erase, and writing data in the correct sequence. Ensure your programming code follows the correct sequence:

Unlock the flash memory.

Erase the sector.

Write the data.

Lock the flash memory again.

Example code to write data to flash:

uint32_t address = 0x08008000; // Flash start address uint32_t data = 0x12345678; // Data to write // Unlock flash memory if (HAL_FLASH_Unlock() == HAL_OK) { if (HAL_FLASH_Program(TYPEPROGRAM_WORD, address, data) != HAL_OK) { // Handle write error } HAL_FLASH_Lock(); // Lock flash memory after writing } Use STM32CubeIDE or STM32CubeProgrammer: If you’re unsure about your programming sequence, try using STM32CubeIDE or STM32CubeProgrammer to write directly to flash. This tool ensures all necessary steps are performed correctly. 5. Incorrect Clock Settings

Cause: The STM32F429NIH6 relies on its system clock to control the speed of various operations, including flash writes. If the clock settings are misconfigured, the flash write operation may not function correctly.

Solution:

Verify Clock Configuration: Ensure that the microcontroller is running with the correct clock settings. Use STM32CubeMX to configure the clock settings and ensure they align with your hardware setup. Check Flash Latency: If the system clock is running at higher speeds, ensure the appropriate flash latency is configured to allow stable flash writes. This is especially important when operating at higher frequencies (e.g., 180 MHz). 6. Read-Out Protection (ROP) Enabled

Cause: STM32 microcontrollers have a Read-Out Protection feature, which can prevent access to flash memory if enabled. If the Read-Out Protection level is set too high, it could prevent writing to the flash.

Solution:

Check the Read-Out Protection (ROP) Level: The STM32F429NIH6 supports three levels of read-out protection: Level 0 (unprotected), Level 1 (full protection), and Level 2 (backdoor protection). Disable ROP (if necessary): You can disable Read-Out Protection using STM32CubeProgrammer or through code. Example: c FLASH_OB_Unlock(); // Unlock Option Bytes FLASH_OB_RDPLevelConfig(FLASH_OB_RDP_Level_0); // Set Read-Out Protection to Level 0 FLASH_OB_Launch(); // Commit the changes Reboot the MCU after making changes to ROP settings to ensure they take effect.

Conclusion

When facing issues with writing to flash memory on the STM32F429NIH6, it’s important to methodically check these common causes: write protection, memory erasure, voltage stability, programming algorithm errors, clock settings, and read-out protection. By following the outlined steps, you should be able to troubleshoot and resolve the issue effectively. Always remember to refer to the STM32F429 datasheet and reference manual for additional insights into the configuration and usage of the flash memory.