I have a friend who wanted me to make him a MIDI gadget, I used a Teensy 4.1 for the SD card slot. That done, he now wants me to forget the SD card, and add a rechargeable coin-type lithium battery (easy recharge circuit with a diode and a resistor) to allow the Teensy to go into low power mode and retain it's memory upon power loss (the original use of the SD card).
Does anyone have any experience and/or ideas about this concept? One concern I have is this type of battery only charges to about 3.1V with the recommended charge circuit, add a diode to prevent back feeding the battery and only provide voltage to the Teensy when no other voltage exists, drops it even further. Or I could possibly use an FET or two to serve the same function, but I'd have to work that one out.
Any thoughts or advice?
Does anyone have any experience and/or ideas about this concept? One concern I have is this type of battery only charges to about 3.1V with the recommended charge circuit, add a diode to prevent back feeding the battery and only provide voltage to the Teensy when no other voltage exists, drops it even further. Or I could possibly use an FET or two to serve the same function, but I'd have to work that one out.
Any thoughts or advice?