SPI slave driver, last 4 Bytes missing (using DMA)

ESP_Sprite
Posts: 2146
Joined: Thu Nov 26, 2015 4:08 am

Re: SPI slave driver, last 4 Bytes missing (using DMA)

Postby ESP_Sprite » Mon Jan 14, 2019 3:14 am

Not that I know. You may be able to use the non-DMA mode up to a point, but that only works up to a limited amount of bytes...

squonk11
Posts: 51
Joined: Wed Mar 01, 2017 6:53 pm
Location: Germany

Re: SPI slave driver, last 4 Bytes missing (using DMA)

Postby squonk11 » Mon Jan 14, 2019 12:21 pm

The non-DMA mode (just using the internal buffer of the ESP32) unfortunately is not a solution for me because I need to receive up to 114 bytes and the internal buffer of the ESP32 is only 32 bytes.
I am wondering if it might be possible to activate an interrupt instead of a DMA transaction. In order to check this I was studying the spi_slave.c driver sources. But for me it is not clear how the HW of the SSI works in detail. Is there some deeper description as given in the ESP32 Technical Refernce Manual?
"Wer glaubt etwas zu sein hat aufgehört etwas zu werden"
Sokrates

squonk11
Posts: 51
Joined: Wed Mar 01, 2017 6:53 pm
Location: Germany

Re: SPI slave driver, last 4 Bytes missing (using DMA)

Postby squonk11 » Thu Jan 17, 2019 5:02 pm

@ESP_sprite : do you know if there will be a new silicon version of the ESP32 with this issue fixed or at least a workaround in ESP-IDF? If not I will need to switch to a different chip because a SPI slave interface suitable for an arbitrary number of incoming data bytes is mandatory for my project.
"Wer glaubt etwas zu sein hat aufgehört etwas zu werden"
Sokrates

ESP_Sprite
Posts: 2146
Joined: Thu Nov 26, 2015 4:08 am

Re: SPI slave driver, last 4 Bytes missing (using DMA)

Postby ESP_Sprite » Sat Jan 19, 2019 3:40 am

We are working on new silicon, and we're very much aware that the SPI in the ESP32 is not perfect... we're trying as hard as we can to get the most common idiosyncracies in the current SPI peripheral out of the design, and I'd imagine this is one of them.

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