Micro:bit Capacitor Charge

//Micro:bit Capacitor Charge
//Adam Robbins 2017

//Capacitor via Variable resistor and switch to Pin 0. Discharge via another switch
//LEDs on Pins 1, 2, 8 and 12

basic.forever(() => {
    let charge: number
    let split: number[]

    charge = pins.analogReadPin(AnalogPin.P0)
    split = divide(charge)
    led.plotBarGraph(charge, 1023)
    pins.analogWritePin(AnalogPin.P1, split[0])
    pins.analogWritePin(AnalogPin.P2, split[1])
    pins.analogWritePin(AnalogPin.P8, split[2])
    pins.analogWritePin(AnalogPin.P12, split[3])
})

function divide(x: number) {
    let a: number
    let b: number
    let c: number
    let d: number
    if (x <= 254) {
        a = x * 4
    } else if (x > 254 && x <= 512) {
        a = 1023
        b = ((x - 254) * 4)
    } else if (x > 512 && x <= 762) {
        a = 1023
        b = 1023
        c = ((x - 512) * 4)
    } else if (x > 762) {
        a = 1023
        b = 1023
        c = 1023
        d = ((x - 762) * 4)
    } else { //error indication
        a = 0
        b = 0
        c = 0
        d = 1023
    }
    return [a, b, c, d]
}