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Electronics => Microcontrollers => Topic started by: exe on November 29, 2024, 10:53:01 pm

Title: esp32s3: maximum display bus speed? Overhead of GPIO matrix
Post by: exe on November 29, 2024, 10:53:01 pm

Hello my friends!

I'm connecting a display (16 bit bus) to esp32s3. I'd like to understand how much speed I can get. The datasheet says the MCU can deliver up to 40MHz on 8080-style bus, pin assignment doesn't matter ("5.2.1.4 LCD and Camera Controller"). However, I also remember that using GPIO matrix makes SPI bus twice slower.

Question: is there a way to bypass GPIO matrix for 16-bit bus and does this make sense? Or it adds just a static latency? I can't figure this out from the datasheet.

Title: Re: esp32s3: maximum display bus speed? Overhead of GPIO matrix
Post by: DavidAlfa on November 30, 2024, 11:03:30 pm

Use IOMux to directly connect pins and peripherals, avoiding the gpio Matrix latency.

https://www.eevblog.com/forum/microcontrollers/esp32-s3-(dual-core-240mhz-blah-blah)-crappy-performance/msg4200127/#msg4200127 (https://www.eevblog.com/forum/microcontrollers/esp32-s3-(dual-core-240mhz-blah-blah)-crappy-performance/msg4200127/#msg4200127)

Title: Re: esp32s3: maximum display bus speed? Overhead of GPIO matrix
Post by: exe on December 04, 2024, 05:43:52 pm

LCD bus doesn't support direct output, unfortunately. I'm attaching screenshot from esp32s technical reference, "Table 6-2. Peripheral Signals via GPIO Matrix"

Title: Re: esp32s3: maximum display bus speed? Overhead of GPIO matrix
Post by: DavidAlfa on December 04, 2024, 08:45:55 pm

Even if the GPIO matrix causes it to go slower, let's say 16MHz, it's a 16-bit parellel bus, should provide decent throughput for 60fps+ in most screens.