For those that might be interested I figured it out and it was indeed per what Sprite_TM stated. Use of the function Cache_WriteBack_Addr in the code solves for the issue. I can now clock out 24bits (3 bytes) in parallel at about 6Mhz from SPIRAM via. the I2S 'LCD Mode'. https://github.com/mrcodetas...

Figured out the problem.

Ending the DMA transfer does not trigger an interrupt by the SPI device. It just sits there in silence. You need to zero out SPI_USR_CONF_NXT to trigger an interrupt.

Solution here: https://github.com/mrcodetastic/esp32s3 ... x_seg_loop

Hi, I have created a 'simple' example of using ESP32S3's Segmented Transfer mode for SPI in order to create a continuous loop. However, I can NEVER get it to trigger a SPI_DMA_SEG_TRANS_DONE_INT interrupt never seems to trigger, no matter what I do. https://github.com/mrcodetastic/esp32s3_spi_dma_tx...

Thanks ESP_Sprite.

If I used say the esp-camera example (https://github.com/espressif/esp32-camera) and re-write it to be an LCD output instead, do you think that could potentially do the trick? I see a bunch of PSRAM data alignment stuff in this code.

Bring back 24-bit or greater parallel output.

ESP32 supported 24-bit parallel LCD... but didn't have enough GPIOs!
S2 does, but apparently doesn't work with PSRAM properly.
S3 has a GDMA that can pull data from PSRAM... but only a 16-bit LCD interface.

I don't want to use the SRAM. I want to use the PSRAM.

The TRM says you can use it for I2S and LCD output, but I there's no guidance anywhere on how to achieve this in code.

Hello. The TRM seems to imply that one can create a buffer in PSRAM memory, and use EDMA to send out via the I2S peripheral (for parallel output LCD mode). However, any attempts I try produce garbage output when any of the buffer is allocated to the ESP32-S2's PSRAM. What is this the case? The TRM s...

That doesn't make sense when I'm sending in 8-bit parallel.

So I need to multiply by 8 even though it is only 31000 bit LENGTH of the transmission... just there are 8 serial lines in parallel.

On another note, the SPI driver code is a dog's breakfast. Espressif could have coded this better.

I want to be able to send an SPI 8-bit transaction of about 32kBytes (so 4000 bits in parallel), but the ESP32-S3 doesn't ever send more than one DMA linked list's worth of data? If I create an spi_transaction_t of 32k, I only ever get about one DMA max payload lengths worth of data? Is there some b...

Edit: Figured out issue.

I was setting the SPICOMMON_BUSFLAG_OCTAL flag to the 'devcfg' not 'buscfg'. Facepalm