Query on GPIOs and nRF51822 development kit

[HLR]

Hi 

I have query on glowing multiple LEDs example 8 LEDS with GPIOs of nrF51422 

So went through nRF51822 series based EDK design files and i see they use 4 LEds to which using 4DPT switch IC 

Can you please explain how they are interfacing LEDs here 

Thanks

[ketiljo]

The DPT switches are there to move the LEDs over to the IO extender (U7) in case a shield is being used. When a shield is not in place, the LEDs are connected directly to P0.21 to P0.24. When a shield in place, the leds are moved over to a I2C IO extended.

If you need as much as 8 LED at the same time, you need to use a driver IC or a transistor pr LED. The nRF51 can't drive 8 LED simultaneously.