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
This patch renames the existing SPI flash API functions to reflect the fact
that the go through the cache:
mp_spiflash_flush -> mp_spiflash_cache_flush
mp_spiflash_read -> mp_spiflash_cached_read
mp_spiflash_write -> mp_spiflash_cached_write
This patch removes the global cache variables from the SPI flash driver and
now requires the user to provide the cache memory themselves, via the SPI
flash configuration struct. This allows to either have a shared cache for
multiple SPI flash devices (by sharing a mp_spiflash_cache_t struct), or
have a single cache per device (or a mix of these options).
To configure the cache use:
mp_spiflash_cache_t spi_bdev_cache;
const mp_spiflash_config_t spiflash_config =
// any bus options
.cache = &spi_bdev_cache,
};
mp_spiflash_read had a bug in it where "dest" and "addr" were incremented
twice for a certain special case. This was fixed, which then allowed the
function to be simplified to reduce code size.
mp_spiflash_write had a bug in it where "src" was not incremented correctly
for the case where the data to be written included the caching buffer as
well as some bytes after this buffer. This was fixed and the resulting
code simplified.
This patch alters the SPI-flash memory driver so that it uses the new
low-level C SPI protocol (from drivers/bus/spi.h) instead of the uPy SPI
protocol (from extmod/machine_spi.h). This allows the SPI-flash driver to
be used independently from the uPy runtime.
This patch takes the software SPI implementation from extmod/machine_spi.c
and moves it to a dedicated file in drivers/bus/softspi.c. This allows the
SPI driver to be used independently of the uPy runtime, making it a more
general component.
The spiflash memory driver is reworked to allow the underlying bus to be
either normal SPI or QSPI. In both cases the bus can be implemented in
software or hardware, as long as the spiflash driver is passed the correct
configuration structure.
Damien George
Andrew Leech
Peter Hinch
roland
Mateusz Kijowski
Hemanth kumar