micropython

embedded microcontroller python micropython

Mateusz Kijowski 1751f5ac7b drivers/sdcard: Do not release CS during the middle of read operations. It seems that some cards do not tolerate releasing the card (by setting CS high) after issuing CMD17 (and 18) and raising it again before reading data. Somehow this causes the 0xfe data start marker not being read and SDCard.readinto() is spinning forever (or until this byte is in the data). This seems to fix weird behviour of SDCard.readblocks() returning different data, also solved hanging os.mount() for my case with a 16GB Infineon card. This stackexchange answer gives more context: https://electronics.stackexchange.com/questions/307214/sd-card-spi-interface-issue-read-operation-returns-0x3f-0xff-instead-of-0x7f-0#307268	6 years ago
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sdcard.py	drivers/sdcard: Do not release CS during the middle of read operations.	6 years ago
sdtest.py	drivers/sdcard: Add support for multi-block read/write; add SD test.	9 years ago

Mateusz Kijowski 1751f5ac7b drivers/sdcard: Do not release CS during the middle of read operations.

It seems that some cards do not tolerate releasing the card (by setting CS
high) after issuing CMD17 (and 18) and raising it again before reading
data. Somehow this causes the 0xfe data start marker not being read and
SDCard.readinto() is spinning forever (or until this byte is in the data).

This seems to fix weird behviour of SDCard.readblocks() returning different
data, also solved hanging os.mount() for my case with a 16GB Infineon card.

This stackexchange answer gives more context:
https://electronics.stackexchange.com/questions/307214/sd-card-spi-interface-issue-read-operation-returns-0x3f-0xff-instead-of-0x7f-0#307268

6 years ago

sdcard.py

drivers/sdcard: Do not release CS during the middle of read operations.

6 years ago

sdtest.py

drivers/sdcard: Add support for multi-block read/write; add SD test.

9 years ago