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ESP32 - LiPo Battery Power and Multifunction uSwitch for ON/OFF and Modes

ftomkiel 1722 4
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  • #1 19364321
    ftomkiel
    Level 4  
    Hi,
    I would like to ask for the expertise of someone firmly on the subject of esp32 based devices (although pretty much any battery powered device).

    I am prototyping a device that is powered by LiPo cells and would ultimately like to have a single uSwitch responsible for controlling it. The schematic of the ON/OFF/Multifunction button would look like this

    Hold - ON/OFF
    Short press - switching between operating modes, in this case the instruction to the ESP which then controls the 0%/50%/100%/STROBO output

    From my research, I could use the Deep Sleep mode and have the device wake up (ON/OFF) and in this case the button would serve as a multifunction because the ESP would be able to verify the current state and duration of the button press by the user and on this basis control not only ON/OFF but also switching between modes.

    A second, more optimal way under battery conditions is i.e. a latching circuit that completely cuts off power to the circuit. But in this case, there is no need to use the button as a multifunction or at least to switch off the device by holding it down; such a solution is better in terms of battery life, but would probably require adding another button responsible for the rest of the functionality to the design.

    Please show me the way, because as far as I know almost every battery powered device from a torch to a phone uses ON/OFF functions via uSwitch and if I want to use ESP32 is it best to use Deep Sleep mode as the off mode of the device? Such a mode will draw according to the datasheet 15uA + loss on the LDO still running. Is this how it is done? Is this how every manufacturer of a device based on a microchip and activated from the uSwitch does it?
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  • #2 19364504
    Anonymous
    Level 1  
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  • #3 19365096
    ftomkiel
    Level 4  
    khoam wrote:
    I think a better solution would be to use a buck-boost converter instead of an LDO, making better use of the battery. An example of such a solution is here: Link
    .
    Why do you think so? An LDO like the MCP1703 will draw about 2.0µA at idle while the solution you gave me draws about 70µA. Admittedly, the LDO I mentioned only puts out a max of 250mA, but it should be enough for tasks requiring low computing power.
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  • #4 19365103
    Anonymous
    Level 1  
  • #5 19365409
    ftomkiel
    Level 4  
    khoam wrote:
    The WiFi transceiver chip alone in the ESP32 at "peak" can consume 240 mA.
    .
    I will be using an ESP with one processor core and the only additional function is BLE. Shucks in that case I don't know what to do but a consumption of about 100uA in "off" mode of the device is pretty poor.
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