Wireless Stick Lite not reading battery voltage

#1

I’m trying to read the battery voltage using the built-in voltage divider attached to GPIO37. According the the Wireless Stick Lite schematic, GPIO37 connects to the voltage divider via what I think is a solder bridge labeled “BR1”. When I measure the resistance between GPIO37 and Vbat I get an open circuit, so it seems to me that BR1 is open. It should measure 220K Ohms.

I tested 3 different Wireless Stick Lite and all were open circuit. When I make the same measurement on my ESP32 LoRa OLED V2.1, I get 220K Ohms as expected. Both boards have the same voltage divider available to GPIO37, but only the Wireless Stick Lite has a solder bridge to GPIO37 shown on the schematic.

I have been able to read battery voltages successfully with the ESP LoRa OLED V2.1, so I know about the use of GPIO21 (Vext) and that it has to be LOW in order to take battery readings.

Can someone tell me how to solder BR1 closed? I can’t see it on the bottom of the board. Perhaps it’s on top under the can?

#2

hi,

please refer the picture:
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#3

My WSL looks a little different. I found a 0K resistor near the same location as your picture, then discovered that BR1 connects to gpio13, not gpio37. Apparently I have a different revision WSL board. Your website does not say anything about different WSL revisions. The schematic diagram Heltec sent me earlier does not show earlier revision. I purchased one of my WSL boards June, 2020 and two more in January 2021. I see now that all three boards are the older revision. All were purchased from Amazon. I paid the higher Amazon price so that I could get them quickly (3 days instead of many weeks from China).

  • Why did I receive obsolete products? Did some “unreleased” prototypes find there way to Amazon warehouses?
  • Why is there no information about different WSL versions at WSL Update Log which shows a picture of my (older) version. There is nothing on the Heltec website that would allow me to know that I received an older version, or that any older versions exist.

WSL_%20BR1_Old_Version

#4

hi,

Our Amazon agents usually buy thousands of development boards from us at one time, and the delay of the version is inevitable.

If you want to buy the latest version of the hardware, please buy it on heltec’s official website.

#5

What is the latest version of the Wireless Stick Lite?

Please send me a link to the pages on your website that document the current version and a link that documents my version. Is there any difference other than the use of pin 13 vs pin37 for battery voltage measurement?

#6

just change the adc pins(13—37)

#7

hi,

the latest hardwar version is V2.1. your hard maybe the V2.0
https://resource.heltec.cn/download/Wireless_Stick_Lite