PCA10056 board voltage abnormal

[xiang san]

Hi，

     I have a question of my "PCA10056 boad", The VDD_NRF voltage is only 1.7V when connect  microUSB of J2, I think one of my board components is broken, can you gei me some suggests。

 Thanks!

[haakonsh]

My first guess would be that UICR has been erased and the high voltage regulator(REGOUT0) is set to it's default state of 1.8V. 

Do you have a J-link pro or similar debugger that you can use to read the content of UICR?

[xiang san]

Does UICR refer to 52840? when connect  microUSB of J3, The  nrf52840  can work and the volatage of VDD_nrf is 3V, In addition, I don't know other methods to read the content of uicr except through microusb of J2.

 according my test,when connect microUSB of J3, VBUS_nrf is 4.7v,VBOOST_SRC is 4.5v,VDD_nrf is 3v,they are normal.when connect microUSB of J2,VBUS is 4.7V ,VBOOST_SRC  is only 2.35v ,VDD_nrf is only 1.75v. According to the schematic diagram I think mybe the diode of D80 is broken,by testing ,When powered on, the voltage drop across the diode is as high as 2.3V, resulting in vboost_ The SRC voltage is only 2.35v, but when it is not powered on, the tube voltage drop is 0.27v, which seems to be normal again . So now I don not konw what is wrong.

[haakonsh]

sorry for the late reply. 

In order to read the UICR you'll need to power the device via J3 and use another j-link to connect to your device via the debug-in or P20 connectors.