CXD5602 GPIO speed

[nimish]

How fast can I grab data from an externally clocked source using the GPIO directly into memory? From 1-4 pins if that matters, absolute max rate would be 44MHz.

[CamilaSouza]

@nimish

I ran a basic test to estimate GPIO speed by only toggling Pin D01 (UART2_TX) on and off using our GPIO API and got a frequency of 905.8kHz
You can probably get it to be higher than that with some optimizations, but 40MHz would definitely not be possible.

I'm attaching the code I wrote for the test and the picture I took from the wave shown on an analyzer.

Code:

#include <arch/board/board.h>
#include <arch/chip/pin.h>

int main(int argc, FAR char *argv[])
{
  while(1){
    board_gpio_write(PIN_UART2_TXD, 0);
    board_gpio_write(PIN_UART2_TXD, 1);
  }
  return 0;
}

[nimish]

@CamilaSouza thanks -- makes sense. Is there any other way to get high speed parallel IO into spresense? I guess I could hack the imaging interface to have the board read data as if it were raw camera data.