amczarny09/11/2017 at 19:05 0 comments

    The initial prototype had 0.96" i2c OLED 128x64. The main benefits are 

    • only two connections (i2c) required from atmega micro-controller. 
    • 'high' resolution 128 x 64

    on the negative side 

    • high power consumption ~ 10mA-20mA depends on number of visible pixels
    • small display size
    • high memory usage 

    The ATMega328P 3.3V will use around 3.5mA. We will have some losses on our Step-Up voltage regulator and other circuits but still 10 mA is a lot. 

    To reduce power consumption I have decided to move to Nokia 5110 84 x 48

    • it consumes around 0.5mA and 1-10mA (for backlight)
    • large display
    • less memory usage


    • SPI interface more pin will be required
    • low resolution 
    • It is less readable than oled

    The connection requires at least 4  lines + 1 line for led but we will also lose MISO pin as it can not be reused as normal digital pin. In total 6 

    • SCE (CE) - GND
    • RST - DigitalPin
    • D/C (DC) - DigitalPin
    • DN  (DIN) - SPI MOSI 
    • SCLK (CLK) - SPI SCK 
    • LED (LIGHT) - PWN Digital Pin
    •  disconnected - MISO 

    The LCD is a separate module and can be easily detached from main pcb