HTCC-AM01 bootloader mode if GPIO7 is LOW

#1

I just got a new PCB for HTCC-AM01 that replaces my earlier version that uses HTCC-AM02. AM02 works without any problem. Also HTCC-AM01 works fine but if I set GPIO07 LOW when resetting, the module goes to bootloader mode. I tested this with couple of modules and all of them go to bootloader if I have either GPIO0 or GPIO07 LOW and module is reset.

This is a big problem for me because I am using GPIO07 for a DIP-switch. I did not find any documents regarding any limitations of usage of GPIO07.

Why is GPIO7 acting like this and is there any way to make it possible to have GPIO07 set LOW so that the bootloader is not activated after reset?

kuva
kuva.png1000×1276 284 KB

1 Like
#2

yes that’s right, please an explanation

#3

hello arit
Is there a solution
my attempts fail. our circuits are the same.

am01
am01.jpg1119×476 243 KB

GPIO0-> 0 - RST ->0 RST->1 GPIO->1 never upload arduino sketch

GPIO0-> 0 - RST ->0 RST->1 GPIO->0 now upload arduino sketch but then go to
bootloader mode

#4

I don’t know how it happened.
Maybe the firmware is faulty
I flashed firmware with @wasn and it’s working now !!!
@wasn

and now GPIO0-> 0 - RST ->0 RST->1 GPIO->1 upload arduino sketch
BUT first time GPIO7 is VCC or pull up !!!

wasn
wasn.jpg1014×469 96.4 KB

#5

Compare once more my schematic to yours. There is major difference in reset and programming GPIO’s. For ex. if you press RST in your configuration it causes a short circuit (3.3V is in that case connected directly to GND). Use 10k pull up resistors as in my picture!

#6

my schema is correct, please check it again.
but the gpio7 problem persists.
same as heltec recommendation scheme.