Hi Jared- I have been testing my stacked setup and it’s been working very well using my Github code (https://github.com/smeisner/AirQualityWing). But I was encountering a problem and wanted to get your take on it.
So far, my testing has been using the following (stacked in the order shown):
- Adafruit OLED FeatherWing
- HUZZAH32
- AQW
- LiPO Battery connected to the HUZZAH32
When I use power via the HUZZAH32 USB port it runs forever. But when I switch to the LiPO battery only (power only applied to VBAT), the V5V0_HAT voltage going to the HPMA is around 2V. Clearly not enough to power it so the code fails to read data from it.
After isolating much of the circuits, I finally determined if I break the VBUS connection and apply 4v0 to VBAT everything works fine. All other pins between the AQW and the HUZZAH32 are connected:
12 Pin connector:
1 (VBAT)
7 (HPMA_EN)
8 (SENSORS_VCC ... although unused)
11 (SCL)
12 (SDA)
16 Pin connector:
2 (3v3)
4 (GND)
14 (RX)
15 (TX)
Any ideas why when the VBUS pin is connected between the uController and the AQW the V5V0 voltage drops to an unacceptable level?
