GPIO Pins for external peripherals

Cellular Boards RAK5010
#1

Issue: Connecting External Peripherals

Setup: To connect LED to RAK5010

Details: I want to use an ext LED to indicate low battery status. However, i am not sure which IO pin I can connect to? From the J12 pinout, there are IO 1-4. But from the schematic, it shows that they are connected to the SIM module. Can someone help?

#2

The IO 1-4 are not connected to SIM module. They are connected to a logic-level shifter then to NRF52840. Here’s the schematic connection. They are named NRF_IO1 to NRF_IO4.

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NRF_IO1 - P0.19
NRF_IO2 - P0.20
NRF_IO3 - P1.02
NRF_IO4 - P1.01

Full schematic can be downloaded on this link https://downloads.rakwireless.com/Cellular/RAK5010/Hardware-Specification/RAK5010-VB_Schematic.pdf

#3

Hi Carl,

What is the pin assignment? In number format? Eg. Is pin 20, IO2?
I have tried to connect an LED to the pin 20 and done a simple test, but LED still doesnt light up, as the voltage at pin 20 is still read as 0V.

 pinMode(20, OUTPUT);
 digitalWrite((20,HIGH);

LED is fine, verified connecting between gnd and Vref.

#4

Pin 19 or 20 should work. What voltage did you put on EXT_VREF?

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#5

Hi Carl,

I missed that part. Vref is not connected to anything at this moment. Can i connect Vbat to Vref ?I do not want to connect any other source to the RAK to make it compact.

#6

Vbat is ok. Doing that, the high voltage level of your IO pin will be the Vbat level too.

#7

Hi Carl,

Thanks. Will try that.