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TTTech Computertechnik AG

Revision 2.1

17 - 20

AS8202NF TTP-C2NF

LED Signals

The LED port consists of three pins. Via the MEDL each of these pins can be independently configured for any of the

three modes of operation. At Power-Up and after Reset the LED port is inactive and only weak pull-down resistors are

connected. After the controller is switched on by the host and when it is processing its initialization, the LED port is

initialized to the selected mode of operation.

Each LED pin can be configured to be either a push/pull driver (drives both LOW and HIGH) or to be only an open-

drain output (drives only LOW).

Table 14. LED Signals

Pin Name

Protocol Mode

Timing Mode

Bus Guardian Mode

LED2

RPV

1

or

Protocol activity7

1. RPV is Remote Pin Voting. RPV is a network-wide agreed signal used typically for agreed power-up or power-

down of the application's external drivers.

Time Overflow

2

2. Time Overflow is active for one clock cycle at the event of an overflow of the internal 16-bit time counter. Time

Tick is active for one clock cycle when the internal time is counted up. Time Overflow and Time Tick can be used

to externally clone the internal time control unit (TCU). With this information the application can precisely sample

and trigger events, for example.

Action Time

3

3. Action Time signals the start of a bus access cycle.

LED1

Sync Valid

4

4. The controller sets this output when cluster synchronization is achieved (after integration from the LISTEN state,

after acknowledge in the COLDSTART state).

Time Tick

2

BDE1

5

5. BDE0 and BDE1 show the Bus Guardian's activity, '1' signals an activated transmitter gate on the respective

channel.

LED0

Protocol activity

6

or RPV

7

6. Protocol activity is typically connected to an optical LED. The flashing frequency and rhythm give a simple view

to the internal TTP protocol state.

7. LED2's RPV mode and LED0's Protocol activity mode can be swapped with a MEDL parameter.

Microtick

8

8. Microtick is the internal main clock signal.

BDE0

5