Solution to the failure of uninterrupted power initialization using SD NAND in STM32F407 MCU

In the field of embedded systems, the combination of the STM32F407 microcontroller unit (MCU) and SD NAND provides a powerful storage solution. However, the problem of uninterrupted power initialization may cause system stability and data integrity to be damaged. We will introduce the initialization problems that may be encountered when integrating the STM32F407 with SD NAND and provide professional solutions.

STM32F407 MCU with MK FOUNDER SD NAND part number MKDV4GCL-ABB solution

Initialization failure is as following photo:

Yellow: miso

Green: mosi

Blue: clk

Yellow: cs

Look at the problem from the photo:

1. MISO (Master Input Slave Output): The MISO signal is the response signal of the SD card. During the initialization process, the SD card sends a specific response code on the MISO line. No response code is detected.

2. Chip select signal (CS), the chip select signal should be pulled low correctly during the initialization process. Check that the CS signal is not pulled low at the correct time point to activate the SD card.

Solution:

1. After the SD card is powered on, send at least 74 clock cycles to the SD card to complete the SD card's self-check and initialization and enter the IDLE state. The CS and MOSI pins must be kept high level.

2. When sending the CMD0 command (0x40) to reset the SD card, you need to pull down the CS signal

3. After sending the CMD0 command, wait for the SD card to return the response data, then wait for 8 clock cycles before pulling up the CS signal

4. In the subsequent CMD8, CMD55 and ACMD41 commands, the CS signal needs to be pulled low before each command is sent. After the command is sent, wait for the response data, and then wait for 8 clock cycles before pulling the CS signal high.

5. The CS signal should be pulled low at the following time points:

Before sending CMD0 command.

Before sending CMD8 command.

Before sending ACMD41 command.

Before sending CMD24 write operation command.

Before sending CMD17 read operation command.

Operation under the condition that the SD card cannot be read and written all the time:

Stagger the SD card reading and writing time, reset the MCU, modify the software timing to stop reading and writing the SD card, and then reset the MCU.

The normal photo is as following:

The combination of STM32F407 MCU and MK FOUNDER SD NAND is suitable for application such as industrial control, intelligent monitoring, medical equipment and smart home, providing these fields with efficient and reliable data storage and processing capabilities.