Use a GPIO in input and output to generate signals internally to peripherals

[Louis]

Hello ,

As mentioned in another question, I would like to use the nrf51822 SPI slave peripheral to benefit from the DMA capability although I want to behave as an SPI master.

To do this, I would like to control the SPI_SS manually and the SPI_SCLK using timers and PPI and then route these GPIOs back into the SPI slave HW.

Unfortunately, I do not have these loopback wired externally and I would like to route them directly inside the pads so I do not need to change the current board layout.

How can I do this?

Thanks

[Stian Røed Hafskjold]

Unfortunately, only one peripheral can be assigned to drive a particular GPIO pin at a time. So when the SPI slave is mapped to physical pins, you can only change these pins externally.