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GPIO15 : "Boot up from flash " or "TX of swapped UART" ?

PostPosted: Sat Sep 15, 2018 8:01 am
by Rasoul
Hi , i'm having a connection through UART and i use serial.swap() to change the pins of UART for having communication with another device . ( i cant use original pins because of problems with Serial programming whitch causes the 2nd device to crash )
after i use serial.swap() the 2 pins for UART are GPIO13 and GPIO15 .
but we should pull-down GPIO15 for booting up from flash ...

how can i use the second UART pins but also making sure that if my module resets it will boot up from flash (and not from SD-Card ) ?

Re: GPIO15 : "Boot up from flash " or "TX of swapped UART"

PostPosted: Sun May 21, 2023 4:23 pm
by Linus Hack
Hello, I am answering this question to help solve this problem. If we decide to connect some interface to the GPIO15 and at the same time we want to guarantee the programming operation (flash) it is sufficient to insert a 1n4148 diode between the GPIO15 and the external circuit and always keeping the 10K pull-down resistor between the GPIO15 and GND .