I want to design a battery powered device that detects proximity (through an IR LED and a photodiode), and displays information on a small screen. As it is an autonomous device, it must be low-power. I chose to work with a digispark dev board that seems to fit my requirements, in terms of power, pinouts, and memory. Here are the components i chose to use:
- Digispark dev board (ATtiny85)
- BPV10NF photodiode
- IR LED TSFF5210
- 0'96 Adafruit 128x64 OLED screen
- a 9V battery
- a push button (it will drive power (software function) on the OLED screen)
- some resistors.
pinouts of the Digispark will be configured as follows:
- P0 --> SDA
- P1 --> Digital output (Reset pin driving)
- P2 --> SCL
- P3 --> Analog input (button pressing detection and pull-up)
- P4 --> Digital or PWM for IR LED (I am not too sure here)
- P5 --> Analog input
So, as I am a beginner in electronics, I am not too sure about my design, particularly concerning the resistors. I made some calculations, for the IRled that led to a 225ohm resistor, in order to avoid damage on micro, but concerning the pull-up resistor and the photodiode one, I am not too sure. Could anybody verify if there is a problem on this design ? Thanks !
So according to what st2000 said, i changed my dev board for a MSP-exp430G2 (that seems to draw less current). I chose a ADM1602K as LCD (with a potentiometer to monitor the contrast), and a TSSP4P38 as IR proximity sensor. As i want to use a Lipo (3v7), i added a XC6206 voltage regulator that seems low-power (around 1µA current draw). the wiring on each pinout of the MSP430 is not definitive, as i only need 2 analog input, and the other are digital output (if i'm not mistaken).
Could you please give me inputs on that circuit ? Thanks !!