Bench Power
Edit on GitHubPowering the beacon on the bench with a supply or power bank, and the voltages you should measure.
Bench Power
For development you want controlled power, not a half-charged cell. This page covers bench supplies and power banks.
Option 1: bench power supply
Set to 3.7-4.2 V with a current limit of 300 mA before connecting. Expect:
- Deep sleep: ~10 uA
- OLED on, radio idle: ~25-40 mA
- Transmitting: ~100-130 mA (ESP32 + PA at +17 dBm)
If the supply shows more than ~300 mA during TX, suspect a wiring fault or a bad PA configuration.
Option 2: USB power bank
A power bank gives 5 V on USB. Feed that into the ESP32’s 5V/VBUS pin (through the onboard AMS1117 to 3.3 V). Do not connect a 5 V power bank directly to the 3V3 rail.
Note: with the TP4056 not in the circuit, battery percentage reads from whatever voltage the divider sees. For bench work, that is fine: you mainly care about the radio and display.
What to measure
| Point | Expected |
|---|---|
| ESP32 3V3 pin to GND | 3.3 V |
| TP4056 BAT+ (with cell) | 3.7-4.2 V |
| Divider midpoint (GPIO 36) | half of BAT+ |
| E22 VCC | 3.3 V |
Current measurement
To measure true sleep current, put the multimeter in series with the battery (uA mode) during deep sleep. The 10 uA figure is the design target; 20-40 uA is normal with leaky modules, over 100 uA means something is staying awake.
First power-on protocol
- Measure 3V3 first, before connecting peripherals.
- Connect display, check it initializes.
- Connect radio, check BUSY settles.
- Connect GPS last, and only if you are testing GPS.
This isolates a wiring error to the last thing you connected.