2019-07-15 05:41 PM
I believe this signal is not needed by the 1bit interface, that only D0, CMD and CK is required. However since I cant get my card responding I start questioning my design. I thought CDIR was only used for SD cards used in SPI mode?
Alternatively I may connect to a free IO to microSD pin 2, or thigh the CDIR pin to a certain level, (LOW for always select). But, I used CubeMX to generate code and it did not give any warning for not selecting SDMMC1_CDIR on PB9 when selecting 1bit mode so this pin is used for LTDC_B7 and stuck there, so if this is the problem, I must alter code to use the gpio I have available for command direction.
Thanks in advance
Vidar
2019-07-15 07:13 PM
No transceiver required for 3V operation in 1-bit mode
In stm32h7xx_hal_conf.f make sure you have :
#define USE_SD_TRANSCEIVER 0 /*!< don't use uSD Transceiver */
2019-07-16 04:13 AM
Thanks Clive, ..
I did that but to no help, but then I noticed that the internal pull-ups was not turned on.
After also enabling these, the uSD card responded perfectly.
Thanks for you help
2019-07-16 06:33 AM
Thanks for reporting back. A lot of designs use external pull-ups, but absent those you'd want the internal ones enabled.
You can also back-off the speed setting, as for short wires don't need the most aggressive slew-rates.
2019-07-16 11:37 AM
Yes, I have set speed to MEDIUM. But for the moment I use a very low peripheral clock speed, only 10 MHz while I was chasing ghosts.
Will monitor the edges to find optimum speed and setting for my board later.
Breg
Vidar