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nRF52840 Feather Express HW problem
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nRF52840 Feather Express HW problem

by softanalle on Wed Apr 14, 2021 5:35 am

Hi,

Question: Is the nRF52840 Feather Express -schema available?

And the background:

I have a simple setup of (Arduino) nRF52840 Feather Express connected to steval-mkiv1-184872 -evaluation board. I was going to use it via I2C bus, and followed the connection diagram almost to last letter.

* I connected SDA/SCL to feather
* I connected VDD and VDDIO to VCC (3.3V)
* I connected GND to feather GND
* I connected SA0 to GND


Then I write more verbally my steps:


I wrote simple Arduino program, to open I2C (Wire -library). The program reads WHO_AM_I successfully.

Next step, I added 8bit temperature reading, again successfully get result 0 -- which means +25'C.

This far everything is ok.

I got more curious; I tried to read long temperature (registers OUT_T_L and OUT_T_H) and combining them to float temperature. No compile errors.

As soon as I flashed the latest changes to Arduino (above mentioned nRF board), flashing was successfull. Program starts....

...board stays blinking only communication LED fast. Board dies.

Quick re-check of cabling, I find that I have missed pull-up resistors. I add the resistors, and connect new board.

I flash the SW and again this new board dies.

It seems that USB F2 is still alive. On connected to USB, and 2 presses of Reset switch changes the device in Flash mod. New bootloader (0.5.0) can be flashed via USB serial. But it does not change anything.

Also it seems that new software can be flashed to board, so I reckon something is still alive. But the board does not start SW after boot. It just stays in blinking mode.

Diagnosis: the board does not give out voltage (3V pin) when connected to USB, so. I guess that LDO has burned. It should however, be able to provide at least 40mA. I however, find that I have not connected CS (of LIS2DW12 sensor) to VDD. But in my understanding this should not cause high current consumption.


Questions:

* in this situation (only CHG led blinks fast), are my Feather boards dead beyond recovery?
* what else could I try


BR


Tommi


simple.ino
Source code, which caused boards to die
(7.91 KiB) Not downloaded yet


PS.1
STEVAL-MKI179V board is LIS2DW12 MEMS acceleration sensor, with DIL24 sockets; for more info: https://www.st.com/en/evaluation-tools/ ... 179v1.html

softanalle
 
Posts: 2
Joined: Wed Apr 14, 2021 4:37 am

Re: nRF52840 Feather Express HW problem

by softanalle on Wed Apr 14, 2021 8:18 am

Updates:

(1) Found a faulty wire used by me in STEVAL -board VDDIO--VCC connection. STEVAL works fine.

(2) I also found the schematics, which I was looking for


Tommi

softanalle
 
Posts: 2
Joined: Wed Apr 14, 2021 4:37 am

Re: nRF52840 Feather Express HW problem

by adafruit_support_carter on Wed Apr 14, 2021 10:59 am

The Downloads section of the products guides is generally where the schematics and other tech info are provided:
https://learn.adafruit.com/introducing- ... /downloads

adafruit_support_carter
 
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Joined: Tue Nov 29, 2016 2:45 pm

Please be positive and constructive with your questions and comments.