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performancesd-card
Deha
Deha

Reputation: 1

Writing to Micro SD from SHARC 21469 idle and speed issues.

I can properly read/write to a 2GB Kingston Micro SD using single pin SPI, but after writing using the WRITE_MULTIPLE_BLOCK command to write several blocks, the card goes into idle mode. I know this because when I try send a command to write more data, the card returns an 'in idle state' flag. I created a work around that pulls the card from idle after each write but this severely reduces the bandwidth. Does anyone know why this happens?

Also, the maximum SPI Baud I have obtained is 1Mbs. When I set the SPI clk to >1MHz the commands do not work properly. If I send commands at a baud of < 1Mbs then send the data at >1Mbs, the data is corrupted. Is there a reason I have not been able to get the 25MHz specification speed as listed in the SDCARD.org spec on p2?

https://www.sdcard.org/developers/tech/sdio/sdio_spec/Simplified_SDIO_Card_Spec.pdf

Upvotes: 0

Views: 193

Answers (1)

Turbo J
Turbo J

Reputation: 7701

I got SPI Speeds less than 1 MBit/s when I tried to use the wrong SPI clock polarity once. Double check this, and this is also a possible candidate as a source for you "idle" error.

Upvotes: 0

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