Any way to disable bootloader from listening to UART1?

perryc
Posts: 25
Joined: Fri Feb 17, 2017 1:29 am

Any way to disable bootloader from listening to UART1?

Postby perryc » Fri Feb 17, 2017 1:51 am

I've got a free running GPS on UART1 that if the darn thing gets a fix and starts sending data it corrupts flash downloads as it appears the data gets merges with the real data being sent on UART0 (MD5 match errors etc). Obvious solution is to move the GPS to UART2 or but wondering is there a way to tell the bootloader to not listen to UART1?

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kolban
Posts: 1683
Joined: Mon Nov 16, 2015 4:43 pm
Location: Texas, USA

Re: Any way to disable bootloader from listening to UART1?

Postby kolban » Fri Feb 17, 2017 4:08 am

Howdy,
The default pins for the UARTs are:

UART0: RX: GPIO3, TX: GPIO1
UART1: RX: GPIO9, TX: GPIO10
UART2: RX: GPIO16, TX: GPIO17

At boot time, UART0 is mapped to the pins above.

For your GPS device, which pins are you using on the ESP32 for RX and TX?

Do remember, that you are not limited to the above pins. You can choose any usable pins for UART1 and UART2 and even redirect UART0s pins.
Free book on ESP32 available here: https://leanpub.com/kolban-ESP32

perryc
Posts: 25
Joined: Fri Feb 17, 2017 1:29 am

Re: Any way to disable bootloader from listening to UART1?

Postby perryc » Fri Feb 17, 2017 4:41 am

Hey I first gotta say your book has been a fantastic resource!

GPS is on the default GPIO's 9&10 for UART1. Didn't have a breadboard for the GPS chip so didn't see this until I soldered up a pcb.
Next rev I'll put the GPS on uart2 and for now I'll cut and solder traces unless there is some software majic workaround.

Perry

WiFive
Posts: 3529
Joined: Tue Dec 01, 2015 7:35 am

Re: Any way to disable bootloader from listening to UART1?

Postby WiFive » Fri Feb 17, 2017 12:55 pm

Your problem in this case is that gpio 9 and 10 are connected to the flash chip. So it is not to do with the bootloader or uart1. Read about the gpio matrix. For most low speed signals there is no reason to use the default pin. Instead you can use the one that is best for PCB layout. But you have to watch the flash pins and strapping pins.

perryc
Posts: 25
Joined: Fri Feb 17, 2017 1:29 am

Re: Any way to disable bootloader from listening to UART1?

Postby perryc » Fri Feb 17, 2017 2:06 pm

ack! well that's embarrassing..... I just copied my esp8266 pin mapping from last years board and didn't scan the table for new conflicts.

Thanks for the help.
Perry

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