Quicklogic Forums

I am following this example: https://github.com/sensiml/esp32_simple_http_uart which shows stacking the QuickFeather on top of the Huzzah ESP32 Feather board.

I'm concerned that this shorts the 3.3V regulators together. I asked on the Adafruit forum and the response was that you cannot stack Feather MCU boards - only an MCU with one or more Wings.

I've run this configuration (battery on Huzzah) and it appears to work but I'm concerned about potential damage. If I power the Huzzah USB port to charge the battery, it seems that I could damage the QuickFeather because it has a GPIO pin on the header where the Huzzah has VBUS.

I've asked SensiML support, but haven't got a response. Is this a safe configuration to use?

Thanks,
Ralph

IO27 on the QuickFeather is default as tri-stated. There is no conflict with the EN pin on the Huzzah32 board with regard to the EN pin.

When the Huzzah32 USB port has power, the VBUS is not connected to the QuickFeather (QF). Therefore the 3.3V regulator on the QF is not active and not driven. There should be no conflict when only one USB port is active.

So, are the GPIO on the QuickFeather 5V tolerant? If I connect USB on the Huzzah, there will be 5V (VBUS) on IO32 of the QuickFeather.

Also, because the VBAT pins are connected together the 3.3V regulators will both be on unless IO27 on the QuickFeather is programmed to disable the regulator on the Huzzah board via the EN pin.

Since the VCCIOB for the ESO S3 is set to 3.3V, there will be leakage when the input voltage to the IO is higher than 3.3V; In this stack up setup, the QuickFeather IO32 is connected to the Huzzah32 VBUS (~5V). The IO32 is default to float son there is no contention. For short term usage, it should be no issue or damage to the IO. It is not recommend to operate in this connection scheme for a long time. If planning to use the setup for long term, it is better to cutoff the IO32 pin to disconnect the QuickFeather to Huzzah32.