Does intra-PSRAM memcpy involve SPI bus data transmission?

wuyuanyi
Posts: 28
Joined: Wed Mar 09, 2022 11:54 am

Does intra-PSRAM memcpy involve SPI bus data transmission?

Postby wuyuanyi » Sun Oct 23, 2022 3:58 pm

Hi,
I am curious if I am memcpying a chunk of memory from PSRAM to PSRAM, does it happen bound within the PSRAM or the data were copied back and forth through the SPI Line?

Another related question is if the Async memcpy in ESP32S3 (https://docs.espressif.com/projects/esp ... emcpy.html) handles the intra-PSRAM memory copy by copying back and forth or not?

ESP_Sprite
Posts: 9739
Joined: Thu Nov 26, 2015 4:08 am

Re: Does intra-PSRAM memcpy involve SPI bus data transmission?

Postby ESP_Sprite » Mon Oct 24, 2022 12:04 am

PSRAM chips don't have functionality to do an internal copy, so it always happens via the SPI lines. Memcpy() also invokes the cache and CPU to do the copy, the async function uses DMA so the CPU is free.

wuyuanyi
Posts: 28
Joined: Wed Mar 09, 2022 11:54 am

Re: Does intra-PSRAM memcpy involve SPI bus data transmission?

Postby wuyuanyi » Mon Oct 24, 2022 6:47 am

ESP_Sprite wrote:
Mon Oct 24, 2022 12:04 am
PSRAM chips don't have functionality to do an internal copy, so it always happens via the SPI lines. Memcpy() also invokes the cache and CPU to do the copy, the async function uses DMA so the CPU is free.
Thanks for your clarification

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