how to calculate current from square pulses

[milner]

my device giving output as square pulses.but would like to control current from the range 50uA to 500uA of square pulses.how to calculate it. can someone help me

[MartinBL]

• The output voltage on the GPIOs will always be the same as your supply voltage (Vdd).

• The GPIOs on the nRF51 can be configured to supply up to 0.5mA in standard drive and 5mA in high drive.

• You can use timers and GPIOs to make a square wave with various frequencies and duty cycles.

• If you need to control the current sent into the electrodes you will need additional circuitry.

• Since the output voltage is constant you will need to know the load resistance to calculate the current (ohm's law).

• I suppose you can measure the current, but then you will need additional circuitry again.