I need to add external memory for datalogging using an RCM6750.
- Do I need any interface chips between the card socket and the processor (like a hot-swap chip) or can it connect directly to the SPI lines?
- Also I’ve read here that the SDflash library uses port B by default. The RCM6750 has its internal flash memory on this port. Will it conflict with the external SD card?
- Where do I define which line is the chip select?
- I already have seen that there is a 2GB limit in Dynamic C. Any way around that either now or in the future? I’m afraid the 2GB cards will not be made forever.
I’ve never dealt with external SD memory before so sorry for all the questions in one.
You could use the following configuration:
microSD | RCM6700
PB0 ---------- SCK
DI ----------- PC4
DO ---------- PC5
CS ---------- PE6
I recommend that our customers should use RCM_43XX_BIOS.LIB’s SPI and SD-related definitions and mutex definitions and code as a guide for setting up the necessary SPI settings and SD card connections using shared serial port B via the “usual” Rx/Tx on parallel port C. Our customers should also consider adding I/O connections to support the SD card’s card detect and write protect features and perhaps also power and LED connections similar to what is done on the RCM4300. Of course, the I/O choices must make sense for the RCM6700 as opposed to the RCM4300.
Our customers will probably also want FAT file system support for the custom SD card. In FAT_CONFIG.LIB, the RCM6700 entries and definitions should be modified, once again following the RCM4300’s example for the SD card. It is also possible, but more complicated, to set up the SD card as a secondary FAT device while leaving the on-core serial flash as the primary FAT device. The best example for this dual-device FAT file system support is actually in Dynamic C 9.62, where that version’s FAT_CONFIG.LIB’s RCM3900 conditional section demonstrates how to set up two different FAT interface drivers with two different devices, the second device being an SD card.
The SD card related macros for the RCM4300 family are defined in Lib\Rabbit4000\BIOSLIB\RCM43XX_BIOS.LIB. In Dynamic C 10.72 the relevant descriptive comments and macro definitions start at line 99 and end at line 211.
Before #use SDFLASH.LIB, the custom application should define its own copy of each of the macros defined within lines 99 through 211 in RCM43XX_BIOS.LIB, as appropriate for the custom SD card I/O connections.
I recommend that our customers should use RCM_43XX_BIOS.LIB’s SPI and SD-related definitions and mutex definitions and code as a guide for setting up the necessary SPI settings and SD card connections using shared serial port B via the “usual” Rx/Tx on parallel port C. Our customer should also consider adding I/O connections to support the SD card’s card detect and write protect features and perhaps also power and LED connections similar to what is done on the RCM4300. Of course, the I/O choices must make sense for the RCM6700 as opposed to the RCM4300.
Our customers will probably also want FAT file system support for the custom SD card. In FAT_CONFIG.LIB, the RCM6700 entries and definitions should be modified, once again following the RCM4300’s example for the SD card. It is also possible, but more complicated, to set up the SD card as a secondary FAT device while leaving the on-core serial flash as the primary FAT device. The best example for this dual-device FAT file system support is actually in Dynamic C 9.62, where that version’s FAT_CONFIG.LIB’s RCM3900 conditional section demonstrates how to set up two different FAT interface drivers with two different devices, the second device being an SD card.
Thank you for the help. I will take a look at the RCM4300 schematics too.