Running without battery - power switch



  • Just ordered 2018 model. Excited to find such a well thought out ESP32 design. Whilst I wait and prototype with my other ESP32 boards, I have a few questions I cannot tell from the schematic as the power module datasheet is not in English. I intend to power it from a stable 5V power supply and want it to turn on when it is powered.

    1. Does the power switch need to be pressed to turn on?
    2. Can it be powered through the pin headers or the 5V and GND of the Grove connector instead of USB?
    3. If so, can it also be connected to USB?

    Are there schematics for the latest 2018 version with the 4MiB PSRAM?

    Also thinking of using the other Grove pins as GPIO. They don't appear to be shared?

    Thanks!



  • Translated section of IP5306 datasheet: "IP5306 can recognize long key and short key operation, PIN5 pin is vacant when the key is not needed. ● The button lasts longer than 50ms, but less than 2s, it means the short press, short press will turn on the power indicator and boost output. ● If the duration of the key is longer than 2s, the long press will activate the light and turn it on or off. ● less than 50ms button action will not have any response. ● Pressing the short key twice within 1 second will turn off the boost output, battery level indicator and lighting LED"

    It sounds like it will power up without pressing the power key, and that may be in the user guide when I zoom into screen shots of it, but I cannot find the pdf to download.

    If I need to, I could remove pin 8 connection of IP5306 to allow simultaneous USB comms (without power) whilst running another 5V input.

    MPU9250 uses the same pins as Grove I2C, so I think I will not be using that port unless some other 2018 versions do not have MPU9250.



  • @jcsbanks Hi JC,

    If you plug the M5 into usb when the M5 is off, the M5 will power on without pressing the on button.

    Powering from the headers is not recommended - github: https://github.com/m5stack/M5Stack/issues/29

    The schematics listed online are for the recent model you ordered - with 4 Mb PS-RAM and MPU9250.
    http://m5stack.com/download/M5-Core-Schematic(20171206).pdf



  • @jcsbanksRunning without battery - power switch 中说:

    MPU9250 uses the same pins as Grove I2C, so I think I will not be using that port unless some other 2018 versions do not have MPU9250.

    You could use an external I2C GPIO expander like the MCP23017 or SX1509 connected via the Grove connector and still use the MPU9250.



  • Is it easy to disable the MPU9250 so that I can use the pins as GPIO? In this case for an ethanol content sensor with pullup to 3.3V. Or would I be better with an M5stack without MPU9250?

    By adding a CAN transceiver inside, I will have a new twisted pair coming out of the case, but if I power through USB C and use Grove for GPIO I could get rid of all the pin headers and use a slimmer base.

    For an order in quantity of hundreds, what customisations are feasible? Having a unit with a CAN transceiver, no battery and a slimmer base already would probably cost less to manufacture, but it depends on the quantities to design another model.


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