23.3.2.4 TCD Inputs

The TCD has two inputs that are connected to the Event System, Input A and Input B. Each input has functionality that is connected to the corresponding output (WOA and WOB). That functionality is controlled by the Event Control x registers (TCDn.EVCTRLA and TCDn.EVCTRLB) and the Input Control x registers (TCDn.INPUTACTRL and TCDn.INPUTBCTRL).

To enable the input Events, write a '1' to the Trigger Event Input Enable bit (TRIGEI) in the Event Control register (TCDn.EVCTRLx). The inputs will be used as a fault detect and/or capture trigger. To enable capture trigger, write a '1' to the ACTION bit in Event Control register (TCDn.EVCTRLx).

There are ten different input modes for the fault detection. The two inputs have the same functionality, except for input blanking which is only supported by input A. Input blanking is configured by the Delay Control and Delay Value registers (TCDn.DLYCTRL and TCDn.DLYVAL).

The inputs are connected to the Event System. The connections between the event source and the TCD input must be configured in the Event System.

An overview of the input system is shown below.

Figure 23-9. TCD Input Overview

There is a delay of 2-3 clock cycles on the TCD synchronizer clock between receiving the input event, processing it, and overriding the outputs. If using the asynchronous event detection, the outputs will override instantly outside the input processing.