January 29, 2022, 01:18:14 am

STM32-P207 SD 4 bit bus

Started by swordman, August 10, 2015, 03:16:12 pm

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Hello everybody.
I bought a STM32-P207 for software prototyping and everything is working flawlessly.
A couple of days ago I started to develop an SD driver, which uses SDIO in 4 bit bus configuration.
No need to say that the current version of the driver is not working.
Earlier today I noticed that schematic shows that the SD is wired by default in SPI mode on SPI3.
Some resistors (0Ohm bridges) connect the SD socket to the SPI bus.
In order to enable the 4 bit bus mode I suppose I have to:
- remove the resistors (R29, R30, R31, R32)
- add bridges on the empty resistors (R24, R22, R25, R26, R27, R28)
Is this enough?
I see the presence of the pull-down of R8... is there any need to remove/move/tamper that too?
Thanks ion advance for the support!



You should consider that the  interrupt signals SD_D0/DCMI_D2 and SD_D1/DCMI_D3 go also to the camera interface (in the schematic located in the block named "640x480 [VGA] CAMERA"). You should also disconnect the camera manually.

The idea was that if you use MMC card by default it works in SPI mode. If you wish to use it in MMC mode then solder 0R resistors on R22, R24, R25, R26, R27, R28 and unsolder R29, R30, R31, R32 (and disconnect the camera interface).

Best regards,
Technical support and documentation manager at Olimex