PCB prototype testing

A project log for ESP32 AX.25/APRS TNC

A minimal-parts AX.25 / APRS TNC that can pair with a phone.

EvanEvan 10/20/2020 at 03:450 Comments

My PCB prototypes arrived today, and I went straight to test them. They generally seem to work!

A day or two after I ordered the PCBs, I noticed that I had used a 6.3V-tolerant capacitor across Vbat and ground. Since the Baofeng uses a 2-cell lithium ion battery, max battery voltage is around 8.4V. Whoops. So, before testing, I desoldered this capacitor.

I did some basic continuity tests, checked the polarity of the diodes, and then applied 5V across the 5V/GND pins on the programming header and checked Vcc. This read 3.57V -- higher than the 3.3V spec, but within the absolute maximum rating of the ESP32. (Once I soldered the ESP32 on, which provided a load for the power supply, this dropped to 3.31V -- much better.)

I did some voltage checks on the programming header to make sure I wasn't going to blow up my wESP32-Prog, then plugged in the programmer and flashed the ESP-IDF Hello World app. This worked, though I had to keep constant torque on the pins to get good contact. The wESP32 has staggered pins for its programming header, which gives a friction fit for the wESP32-Prog. I had meant to do this, but didn't get around to it before ordering.

Things to change for revision 2: