Changes To The MMC / SD Memory Card Driver Files

Transcription

1 MMC / SD Memory Card FAT16 / FAT32 Driver Revision History This document lists changes that have been made to the driver project files to allow past customers to easily check for recent updates / bug fixes since they purchased their project. Changes To The MMC / SD Memory Card Driver Files First released version. Comments where FFC_DI is used we're misleading as they specified DO, relating to the memory card pin, rather than DI used in the code - comments corrected. 'while (!FFS_SPI_BUF_FULL)' in function ffs_write_byte in mem-mmcsd.c had no semicolon so the following return statement would occur immediately - corrected. Added the following to the function ffs_process in mem-mmcsd.c just after 'ffs_bytes_per_sector = 512;' and just before '//----- READ THE MASTER BOOT RECORD -----' as this fixed a user reported issue where writing files to the card would cause the card to require re-formatting:- FFS_CE = 1; //De-select card ffs_write_byte(0xff); //Send extra clock pulses in case card is still completing an operation FFS_CE = 0; //Re-select card Revision A This fixed a rare issue where some cards would become corrupted due to the card not processing some commands sent to it. In the file mem-mmcsd.h add the following define after #define FFS_DRIVER_GEN_512_BYTE_BUFFER:- #define DO_BUSY_STATE_ACCESS_DELAY Nop(); //('Nop();' is a single cycle null instruction for the C18 compiler, include multiple times if required to provide time for the card to drive the DO line if it needs to) Then in the file mem-mmcsd.c search on all 3 occurrences of the following line:- and add the this line before each:- Revision B The driver was not specifically using a low SPI bus speed for initialising a new card, which some cards require. In the file mem-mmcsd.h add the following define after #define FFS_CD_PIN_NC:- //SPI BUS LOW SPEED (Max 400KHz) //- Adjust as required for the microcontroller and instruction clock frequency being used

2 #define SPI_BUS_SET_TO_LOW_SPEED SSPCON1bits.SSPM3 = 0; SSPCON1bits.SSPM2 = 0; SSPCON1bits.SSPM1 = 1; SSPCON1bits.SSPM0 = 0; //SPI BUS FULL SPEED (Max 20MHz) //- Adjust as required for the microcontroller and instruction clock frequency being used #define SPI_BUS_SET_TO_FULL_SPEED SSPCON1bits.SSPM3 = 0; SSPCON1bits.SSPM2 = 0; SSPCON1bits.SSPM1 = 0; SSPCON1bits.SSPM0 = 0; Then in the function ffs_process add the following after //----- INITIALISE NEW MMC / SD CARD SPI_BUS_SET_TO_LOW_SPEED; And add the following before //Send command 1 (do initialise) SPI_BUS_SET_TO_FULL_SPEED; V1.07 Re-worked card initialise to include CMD8 for SD V2.00 compliance and CMD58 to determine card capacity type Added detection of MMC or SD card during initialisation, allowing higher 25MHz bus speed to be selected for SD cards. Added SDHC and MMC plus high capacity card support. Added optional SD write protect pin checking. V1.08 Added support for the Microchip C30 compiler. ffs_read_byte now reads the received byte after transmit is complete, to deal with devices that require this or will overflow. Added optional real time clock support. File creation, last modified and last accessed time and date values are automatically stored if enabled. When closing a file if the last write to the card before it is removed or powered down just occurred some cards have been found to not store the last sector written. In ffs_fclose we now check for card still busy and provide additional clock pulses if it is, by adding the following before the return statement:- FFS_CE = 0; //Select the card FFS_CE = 1; //Deselect the card V1.09 To fix possible problem when time and date stamping files, in mem-ffs.c added (WORD) in front of each occurance of FFS_RTC_YEAR, FFS_RTC_MONTH FFS_RTC_DATE, FFS_RTC_HOURS, FFS_RTC_MINUTES, FFS_RTC_SECONDS to ensure values are treated as 16 bit during bit shift operations. To fix issue with very large cards, in mem-mmcsd.c corrected two occurances of: ffs_write_byte((byte)((sector_lba & 0xff0000) >> 24)); //Data to be: ffs_write_byte((byte)((sector_lba & 0xff000000) >> 24)); //Data To correct minor error, in mem-ffs.c function ffs_get_next_free_cluster changed the following 2 lines:- w_data = (DWORD)*buffer_pointer++; w_data = (DWORD)(*buffer_pointer++) << 8; to be: w_data = (WORD)*buffer_pointer++; w_data = (WORD)(*buffer_pointer++) << 8; V1.10 Direct support added for CrossWorks for ARM compiler using NXP 32bit Arm micro.

3 FFS_CE output pin definition modified to support pin set and pin clear registers where needed. Added ffs_change_file_size() function. The ffs_check_command_response_byte function relied on the last response value being retained in FFS_SPI_RX_BYTE_BUFFER as the value was read again and tested by various functions which called ffs_check_command_response_byte. This is not suitable for microcontrollers that have a fifo buffer on the SPI port receive. Changed to use a new global variable called chk_cmd_response_data in which the FFS_SPI_RX_BYTE_BUFFER value is stored and which the calling functions instead use to test with. It has been found in some circumstances that corruption issues can be solved by replacing the following occurrences: with this: The cause of this is unknown as the specification does not appear to require this, but it does not prohibit it either so it is sensible to include. Added the following at the end of ffs_flush: //----- ENSURE CARD HAS COMPLETED LAST WRITE PROCESS //When closing a file if the last write to the card before it is removed or powered down just occurred //some cards have been found to not store the last sector written. If the card is flagging that its busy //then provide clock pulses to allow it to complete its last operation FFS_CE(0); //Select the card FFS_CE(1); //Deselect the card return(0); Removed the ENSURE CARD HAS COMPLETED LAST WRITE PROCESS section from ffs_fclose as this is now provided by ffs_flush. ffs_read_sector_to_buffer function modified to include retry if the read fails to deal with rare cards found to not action the command if busy whilst not actually flagging that they are busy. ffs_write_sector_from_buffer function modified to include retry if the read fails to deal with rare cards found to not action the command if busy whilst not actually flagging that they are busy.. ffs_remove function updated to ensure both FAT tables are updated. Issue fixed in ffs_fputc where overwriting within a file across a cluster boundary could cause corruption. In mem-ffs.c changed: bytes_to_new_posn -= (DWORD)0 - offset; to be bytes_to_new_posn -= (DWORD)(0 - offset); as this solved a "unary minus operator applied to unsigned type" error with the Codewarrior compiler.

4 Changes To The Sample Project Files First released version. Corrected RB3 pin TRIS definition from an input to an output (LED2 pin). V1.07 V1.08 Changed sample project to run on a PIC18LF4620 at +3.3V our_file_0 and our_file_1 definitions changed to static in process_mode to deal with file close on next call if an error occurs. Changed c_string_buffer definition in process_mode to 60 bytes as the previous length was too short to hold text_file_line2_string, causing memory overflow when the following line was executed: ffs_fread(c_string_buffer, sizeof(char), (int)strlen(text_file_line2_string), our_file_1); V1.09 V1.10 NXP LPC2365 ARM sample project added. Special Note Regarding SPI Bus Please see the: Signal Noise Issues With MMC & SD Memory Cards (& Clocked Devices In General) page in the resources area of our web site for details of a common problem experienced when using MMC and SD memory cards. Some manufacturers demo / evaluation boards have been found to suffer from this issue. Many of the PIC microcontrollers have silicon bug issues that are detailed in the Microchip errata sheets. If you are experiencing problems with a PIC microcontroller accessing cards check the errata sheet for the device you are using.

5 Changes To The Technical Manual V1.00 Original release V1.01 Added sections on Fast Reading Of Bulk File Data and Fast Writing Of Bulk File Data. Added Searching In The Directory section to demonstrate how it is possible to search in the root directory for files. Updated schematic for PIC18 sample project at the end of this manual with correction to PIC pinning to match sample project code. Updated Driver Technical Overview section with explanation of using SD cards with capacities above 1GB and with the addition of SDHC and MMC Plus high capacity card compatibility. Minor additions to other sections of the manual. Updated various sections for changed PIC18 sample project microcontroller, C30 compiler support and real time clock support. New look and re-structured with new format to make it easier to be quickly up and running with the driver. Added code examples to the Fast Reading Of Bulk File Data and Fast Writing Of Bulk File Data sections. NXP LPC2365 ARM sample project and ffs_change_file_size function added.