I've created an UIFlow2 example (M5CoreS3_Ext_Usb_Power_UIFlow2.0.1) showcasing switching ext. power output (Groove port) and USB power output. You can find it in the UIFlow2 Play Zone.

Thanks
Felix

I am glad to hear you got it working (at least with USB-C power).

BTW: My M5CoreS3 (running UIFlow2 firmware) provides power to all Groove ports (A/B/C) in both cases: running from USB-C or battery.

In your hardware setup, what do you need the 5 V of the Groove port for? If you have a multimeter it should be relatively easy to verify 5 V being present or not.

Thanks
Felix

It looks like the bad thing is from AXP2101 power chip, all the PORTs were set to 5V? Please, any idea of how to lower voltage to 3.3V.
I will also find a multimeter to give a test.

on your graphic USB-C is not PORT C (blue) - unfortunately it is drawn in blue - but this is USB port which you are connecting your Laptop /pc to M5Stack

in general on Ports A/B/C wires blk/red are power pins with gnd/5v on them where other two pins wht/yellow are data/sensor pins with 3.3v expected

I am not sure you fully understand the concept of how the Groove port of M5Stack devices are setup.

• Power (red wire) provides 5 V to M5Stack units (which if required turn the 5 V internally to 3.3 V using an DC/DC converter or LDO).
• Data lines (yellow and white wire) use 3.3 V
• GND (black wire)

In your case I assume the 3rd party device (Arduino) is already powered by its own power supply. If yes, then there is no need to use the power (red wire) of the M5Stack.

If the 3rd party device is using 3.3 V on its data lines (TX and RX) then the wiring is as follows:

M5Stack (3.3 V) TX <---> RX (3.3 V) of 3rd party device
M5Stack (3.3 V) RX <---> TX (3.3 V) of 3rd party device
M5Stack GND <---> GND of 3rd party device

If the 3rd party device is using 5 V on its data lines (Tx and RX) then the wiring is as follows:

M5Stack (3.3 V) TX <---> Level shifter <---> RX (5 V) of 3rd party device
M5Stack (3.3 V) RX <---> Level shifter <---> TX (5 V) of 3rd party device
M5Stack GND <---> GND of 3rd party device

Here is an example M5Stack unit which uses an DC/DC converter to lower the 5 V to 3.3 V and includes level shifters for the data lines. See schematic.

Thanks
Felix

like @robski already mentioned, you only need level shifter if your target board TX and RX pins are different from M5Stack Groove port, which uses 3.3 V on its data pins. (Only the red wire of the Groove port, providing power to the M5Stack units, is 5 V.)

Are you sure your target board uses 3.3 V on the data pins? Arduino boards (especially old ones) mostly use 5 V on their data pins.

Thanks
Felix

please note: while Groove ports on M5Stack cores provide 5 V power, the data pins are only 3.3 V tolerant. Which means you might need some level shifters to make a third party product work.

Do you have a link to that 3rd party product?

Thanks
Felix

there is no need for that when using UIFlow2. UIFlow2 firmware automatically turns the power on for all ports. (The FAQ comment is only relevant when programming with Arduino.)

What is the serial device you are trying to read from and write to? (I was testing with a SIM7080 modem, btw.)

Thanks
Felix

Would that be the reason? How can I do that in mpy? In your mpy and C project, you never use this powerModeSet function.

Many thanks again!

I didn't find any examples in Github either

@zhoubinx for some examples go to uiflow1 flow.m5stack.com then under UART blocks you can find pass thru and sim800 examples

in UIFlow2 the UART blocks, unfortunately, are broken (for M5CoreS3 at least). Using UART1 tries to initialize rts and cts with -1 which leads to the "invalid pin" error.

@m5stack : please fix. Thank you.

But there is a way to get around that error using the Execute mpy code block and omitting the extended parameters like rts etc.. I've uploaded an example into the UIFlow2 Play Zone called: M5CoreS3_UART_PortC_UIFlow2.0.1

Thanks
Felix

uiflow1
uart1 = machine.UART(1, tx=17, rx=16)
uart1.init(9600, bits=8, parity=None, stop=1)

uiflow2
setup block:
uart0.init(baudrate=115200, bits=8, parity=None, stop=1, tx=17, rx=16, rts=-1, cts=-1, txbuf=256, rxbuf=256, timeout=0, timeout_char=0, invert=0, flow=0)

init block:
uart0 = UART(0, baudrate=115200, bits=8, parity=None, stop=1, tx=17, rx=16, rts=-1, cts=-1, txbuf=256, rxbuf=256, timeout=0, timeout_char=0, invert=0, flow=0)