Self-powered temperature sensor with screen display

Hello there,

I am currently creating a project that is self powered via the source of body heat with the use of a thermoelectric generator (TEG). The project requires to display temperature data on an screen for a short duration of time. I have created a circuit which is capable of outputting a stable voltage output at either of these voltages of 5 ,4.1 ,3.3 ,2.35 V with the use of LTC3108 the power output would be in the magnitude of low micro watts. The energy is stored in a capacitor and will be released depending on the requirement of the screen, temperature sensor (LM35) and the micro controller. I will be putting the MCU into sleep mode to save on running power and waking it up for a short duration of time to collect temperature data and pass it to the screen.

I am looking for suggestions on low power micro-controllers I have looked at the ATmega328 and the MSP430 as it has 4 different power saving modes, however if you reduce the power on the MSP to a certain magnitude the MCU is incapable of waking itself back up without external input ( I am unsure of how exactly that works). I would like to ideally have an MCU at an extremely low sleep mode, and have the capability to wake itself up without an external input. I have also considered the Nokia 5110 LCD screen as it only draws 0.2mA.

Any information is appreciated!

You need a "reset controller" or "reset supervisor" to accomplish what you want. Most are three terminal devices that hold the reset until the power supply voltage has reached a stable level.

For that to work, the MCU has to consume very little power in the reset state, and unfortunately, the ATmega chips consume several mA. In that case the alternative is to have the reset controller control the MCU power supply, rather than the reset pin.

See Voltage Supervisors | Microchip Technology

what is purpose of this project?

If really low power is needed, the ESP32 has 2 processors. One processor is the dual core processor, the other processor is the ULP (Ultra Low Power) processor.

The ULP can be programmed under the Arduino IDE. The Main processor can be put to sleep, shutdown and powered off, with the ULP doing all the work.

Search - ESP32 - — ESP-IDF Programming Guide latest documentation (espressif.com)

To display body temperature without the need of batteries with the use of energy sourced from a human body.

You're hilarious

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