AB01 LoRa dependent on Vext?

#1

Hi All,

I was playing around with LoRaWanMinimal_APP and got rid of all of the code that is using LED and serial printing.
I did it as I am building a wrapper around it.
In my project I am turning off Vext when configuration is such that the user doesn’t want any LED do be lit.

I have spotted that whenever I turn off Vext I can’t pass joinABP() call, whereas it is working when Vext is turned on.

Is there any dependency of any LoRa-related code from SDK to Vext being enabled?

Thanks for a hint if any.

Grzegorz

#2

It is recommended to use lorawan’s program to give it a try.

#3

Hello @navi,

Thank you for your response.
Could you elaborate more on your proposal? What do you exactly mean?
What shall I do and what would be the answer for my question regarding LoRa module and Vext?

Grzegorz

#4

vext does not affect lora.

#5

As can be seen from the schematic diagram, Vext is equivalent to a branch of 3.3V, and the switch of Vext is controlled by the MOS tube, which has nothing to do with the LoRa part.
https://resource.heltec.cn/download/CubeCell/HTCC-AB01/HTCC-AB01_SchematicDiagram.pdf

#6

Thanks all for your answers,

I was suspecting that maybe internally GPIO6 might be responsible for some interaction.

I will investigate more where is the issue - unfortunately absence of working SWD makes it a bit harder.

Grzegorz

#7

I’d like to get back with a feedback on the problem.

The issue I’ve observed was caused by other problem.
By board has attached external GPS receiver and is powered from the Vext.
To support communication I am using softSerial implementation which is enabling interrupt on RX pin.
When Vext was shut down a garbage appeared on RX pin causing endless interrupt trigerring leading to program stall.

A remedy was to write a wrapper class allowing for disabling and re-opening communication which takes care of the interrupt setup. After that it is possible to turn off the GPS power (Vext) and keep the program runing.

Best regards
Grzegorz

#8

Hi, i’m brazilian student and i want do the same thing and i’ve the same problem. Could you show how to write a wrapper class to control de Vext pin to torn off, torn on a GPS?

i are use a cubecell HTCC-AB01 with a beitian GPS BN220