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Altera_Forum
Honored Contributor I
785 Views

Cyclone V sdcard pull-up

Hi All 

 

According to Cyclone® V Device Family Pin Connection Guidelines - SDMMC_CMD and SDMMC_D0 should have 10k pull-ups but there is no mention of 

pull-ups for SDMMC_D1, SDMMC_D2, SDMMC_D3. Does anyone know if it is correct to have a pull-up on those pins. 

 

Thanks for advice.
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2 Replies
Altera_Forum
Honored Contributor I
50 Views

Hi, you are right it is recommended to have pull up on those data pins. I looked at the dev kit schematic and also the MMC jedec specification, the pull ups are recommended. Please note however that on D3, the SD simplified specification mention that there is an internal pull up (in SD card) that can be disabled by software.  

https://members.sdcard.org/downloads/pls/simplified_specs/part1_410.pdf
Altera_Forum
Honored Contributor I
50 Views

Thanks for answering. The reason I ask is that some of our custom boards fails in 4-bit mode, but works in 1-bit mode. Anyone have the same experience?