There are two MUX subsystems on Concerto, one used by the M3 Master subsystem and one used by the C28x Control subsystem. At reset, all of the GPIOs belong to the M3. After the boot, the M3 is responsible for allocating pins to the Control subsystem. Once the pins have been allocated, the assignments can be locked for safety. Notice, that if the one follows the input paths, the input signal always goes to the Control subsystem as well as the Master subsystem. This means that the M3 cannot block inputs to the Control subsystem, which might be important. For example, signals like trip inputs to the ePWMs should never be blocked. The C28x can also read the state of the pin in its GPIO data register even if the pin is assigned to the M3 MUX subsystem. The input qualification that goes to the Control subsystem is the same on Delfino and Piccolo devices. This includes a Sync (which has no qualification) to C28x system clock signal out, or Sync to system clock signal out plus a filter. Notice on the output side the open drain logic and the pull resisters can only be configured by the M3. This is true even if the pin is assigned to the C28x Control subsystem. Pull ups are disabled on default, which is different than the C2000 devices. Open drain is available on all GPIO outputs. The following features are not supported on Concerto, the IO drive, slew rate and pull downs.