How long does the reset-Pin triggered? about esp-link HOT 3 OPEN

Looks like 2ms, it was simply to find in the code. If you really want to code your own, you should learn how to search, and understand others code.

serbridgeReset()
{
if (mcu_reset_pin >= 0) {
#ifdef SERBR_DBG
os_printf("MCU reset gpio%d\n", mcu_reset_pin);
#endif
GPIO_OUTPUT_SET(mcu_reset_pin, 0);
os_delay_us(2000L); // esp8266 needs at least 1ms reset pulse, it seems...
GPIO_DIS_OUTPUT(mcu_reset_pin);
}
#ifdef SERBR_DBG
else { os_printf("MCU reset: no pin\n"); }
#endif
}

from esp-link.

I've known for a while that the Lock bit is the problem.

Naturally, I examined the code and tested it, as well as the code for the bootloader. Just curious about why it doesn't jump into the UART programming session.

It may function even with 1 ms or less of trigger time. Make sure the Atmega has a bootloader and that the lock bit didn't go wrong.

The lock bit may be set during bootloader burning and removed if an SPI programmer is used.

Read others code is not the way to solve the problem, must know why they did that.

from esp-link.

The timing for the bootloader to be ready to acknowledge sync after reboot, I suspect is different for each board. The approach seems to be, start sending sync immediately after reboot and REPEAT until sync reply or to a count of 10 tries and then fail. The same thing happens happens with boards directly connected to usb. Arduino IDE tries 10 times. There is some delay between repeated sync attempts I would guess.

from esp-link.