The MSC interface provides a serial communication link typically used to connect power switches or other peripheral devices. The serial communication link includes a fast synchronous downstream channel and a slow asynchronous upstream channel.

The following block diagram of the MSC interface shows a global view of the MSC interface signals.

Figure 1. MSC block diagram

The MSC module features functional extensions, but is backward compatible with the previous microcontroller generations.

The downstream and upstream channels of the MSC module communicate with the external world through nine I/O lines. Eight output lines are required for the serial communication of the downstream channel (clock, data and enable signals). One out of the eight input lines SDI[7:0] is used as serial data input signal for the upstream channel. The source of the serial data to be transmitted by the downstream channel can be MSC register contents or data that is provided at the ALTINL/ALTINH input lines. These input lines are typically connected to other on-chip peripheral units (for example with a timer unit like the GTM). A Port Emergency Stop input signal makes it possible to set bits of the serial data stream to dedicated values in case of emergency.

Clock control, address decoding and interrupt service request control are managed outside the MSC module kernel. Service request outputs are able to trigger an interrupt or a DMA request.

In MSC+ mode 2 lines are required for the serial communication of the downstream channel (since clock, data and enable are embedded in one pair line).