Sorry about the mess with transaction/transmission usage. I've edited the post to be more clear. The problem exists only when using the hardware CS (.spics_io_num > 0), because then the spi hardware activates/deactivates the CS. I'm always using the software CS (.spics_io_num = -1 & .spics_ext_io_nu...

Thank you for the suggestion about C++ guard, I'll add it. About the CS problem, please try to use "software CS": spi_nodma_device_interface_config_t devcfg={ ........ .spics_io_num=-1, //we will use "software" CS pin .spics_ext_io_num=PIN_NUM_CS, //your "software" CS pin ........ }; spi_nodma_trans...

@rsimpsonbusa Sorry, I've only tested the driver locally. I have now changed the conflicting functions and struct names in spi_master_nodma driver, so now you can place spi_master_nodma.c in <esp-idf_path>/components/driver directory and spi_master_nodma.h in <esp-df_path>/components/driver/include/...

Is this issue considered so unimportant or is it so complicated to implement the support?

I've had similar problems with SPI reads (see https://www.esp32.com/viewtopic.php?f=14&t=1527 ). I'm now using non DMA spi driver ( https://www.esp32.com/viewtopic.php?f=18&t=1546 ) which passes all my tests for all combinations of write/reads. If your processor has nothing useful to do during the l...

Sometimes, using the spi driver not based on DMA transfer is more convenient. I've created a new nonDMA spi_master driver (based on esp-idf spi_master) which is available on GitHub. https://github.com/loboris/ESP32_SPI_MASTER_NODMA_EXAMPLE Main features Transfers data to SPI device in direct mode, n...

It looks like there is serious bug in spi-master receive when DMA is used. I was testing it with ILI9341 display with application based on spi-master example (the example itself works ok). I've added the function to read line of data from display. Display data format (when read) is: dummy_byte [R_by...

https://github.com/loboris/ESP32_NEW_SPI_MASTER_EXAMPLE Driver modifications Number of the devices attached to the bus which uses hw CS can be 3 ( NO_CS ) as in original driver Additional devices which does not use hw CS can be attached to the bus, up to NO_DEV Additional parameter spics_ext_io_num...

Ooops.... I can set spics_io_num = -1, but when I call spi_bus_add_device > 3 times, driver still said E (199) spi_master: spi_bus_add_device(326): no free cs pins for host .... If you wan to use more than 3 devices, you have to modify spi_bus_add_device() function, something like this: #define NO_...

You can add an arbitrary (well, with the current driver, 3 per host) SPI memory devices to the ESP32 and you can access them using DMA transfers. However, only one device can be memory mapped, and you're limited to 4MiB of memory mapped memory. Also, at the moment memory mapping is not supported in...