![]() To bring the card specification in line with company policies, it is necessary to modify the CID value. The default CID value of a card manufacturer might not be in line with the company’s specifications. Companies may use specific IP methods or strategies to control their content. Modifying the CID value on a microSD Card might be necessary because the content owner must validate the content information. The CID number can also be combined with other data on the card to create signatures that can be used for verification of the validity. CID can also be used to verify that the card has not been altered or tampered with. The CID number can also be used to verify card authenticity and data. It can be used to identify it, verify its authenticity, track its performance, and so on. The unique identifier of the memory card is the CID number. Programming can be done with the CID value. The card model and controller will determine the CID value, so the command used to read it will differ depending on which manufacturer the card is manufactured. The command must also be sent to the vendor-specific register of the card, which cannot be accessed by the USB bus. To read the CID value of a Secure Digital card, however, you will need to issue a vendor command to the controller. ![]() The Universal Serial Bus (USB) can be used to read the CID value on a Secure Digital card. This method is available.Ĭommon questions include how to read or write a CID value to the read-only memory space of a Secure Digital card (either microSD or SD). There are situations when content owners might want to modify CID values to conform to their IP (Intellectual Property). It cannot be changed, duplicated, or modified by any user. The CID value is stored in Read Only Memory (ROM). ![]() It is done during the card creation stage. The manufacturing process includes the writing of the CID value. It is used to identify the card and verify its authenticity. It is usually a 16-digit number that is unique to each card. It is stored in the card’s read-only memory and used to track card usage and performance. This article provides a basic overview of how to read and write CID values from a Secure Digital memory card.ĬID numbers, also known as Card ID numbers, are unique identifiers assigned to Secure Digital memory cards. There are many theories on the internet, but there are not many clear answers. I assumed SD card initialization is not properly working now, but can't see any critical differences between H7 and F7 HAL Library.The reading and writing CID values to microSD cards is still a mystery. My Previous board used STM32F743NI MCU and I used SDCARD before, and didn't have any trouble with capacity of SD Card I was using. I've tried 0, 0xFFFFFFFF, but 4GB SD card still works.I don't understand why.ģ. I know the have to be, but it seems it doesn't matter. As you can see, I've tested with variety of arguments for CMD1. (It took 70 'seconds' after the debugging, before the modification it took 1 second when I used 2GB SD card.) Can you tell me why?Ģ. After I changed the code, 4GB SD Card works, but total file-read speed has been significantly slowed down. Hsd->SdCard.Class = (SDMMC_GetResponse(hsd->Instance, SDMMC_RESP2) > 20) Įrrorstate = SDMMC_CmdSelDesel(hsd->Instance, (uint32_t)(((uint32_t)hsd->SdCard.RelCardAdd) Instance, 0x40000000) Hsd->CSD = SDMMC_GetResponse(hsd->Instance, SDMMC_RESP4) Hsd->CSD = SDMMC_GetResponse(hsd->Instance, SDMMC_RESP3) Hsd->CSD = SDMMC_GetResponse(hsd->Instance, SDMMC_RESP2) * Send CMD9 SEND_CSD with argument as card's RCA */Įrrorstate = SDMMC_CmdSendCSD(hsd->Instance, (uint32_t)(hsd->SdCard.RelCardAdd CSD = SDMMC_GetResponse(hsd->Instance, SDMMC_RESP1) * Send CMD3 SET_REL_ADDR with argument 0 */Įrrorstate = SDMMC_CmdSetRelAdd(hsd->Instance, &sd_rca) Hsd->CID = SDMMC_GetResponse(hsd->Instance, SDMMC_RESP4) Hsd->CID = SDMMC_GetResponse(hsd->Instance, SDMMC_RESP3) Hsd->CID = SDMMC_GetResponse(hsd->Instance, SDMMC_RESP2) ![]() Hsd->CID = SDMMC_GetResponse(hsd->Instance, SDMMC_RESP1) * Get Card identification number data */ Return HAL_SD_ERROR_REQUEST_NOT_APPLICABLE Įrrorstate = SDMMC_CmdSendCID(hsd->Instance) If(SDMMC_GetPowerState(hsd->Instance) = 0) Static uint32_t SD_InitCard(SD_HandleTypeDef *hsd) , and modified SD_InitCard() function in stm32h7xx_hal_sd.c and inserted CMD1 code like below. I've tested the project on my own board and it worked as expected when I use 2GB SD card, but it failed at f_open() when I use 4GB SD card. I'm not using the Eval board for the project, so what I've done is remove MFX I/O related codes from BSP sd.c driver file. My MCU is STM32H743XI, and the base for the project, I modified the FatFS uSD standalone application example in Cube FW for H7 V1.2.0, for STM32H743I-EVAL board. I'm currently working on a project that needs to 'Read' a File in SDCARD.
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