twi with shorts

Nordic has kept the old version PPI of twi_hw_master around to be
compatible with old hardware.

Problem is PPI version is not compatible with BLE.

Don't use twi_hw_master if you have old hardware.

If you have new hardware such as nrf51422 E00, you can use twi_hw_master
but you must uses SHORTS.
twi with shorts

Nordic has kept the old version PPI of twi_hw_master around to be
compatible with old hardware.

Problem is PPI version is not compatible with BLE.

Don't use twi_hw_master if you have old hardware.

If you have new hardware such as nrf51422 E00, you can use twi_hw_master
but you must uses SHORTS.