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TTTech Computertechnik AG

Revision 2.1

15 - 20

AS8202NF TTP-C2NF

TTP Bus Interface

The AS8202NF contains two TTP bus units, one for each TTP channel, building the TTP bus interface. Each TTP bus

channel contains a transmitter and a receiver and can be configured to be either in the asynchronous or synchronous

mode of operation. Note that the two channels (channel 0 and channel 1) can be configured independently for either of

these modes.

The drivers of the TxD and CTS pins are actively driven only during a transmission window, all the other time the

drivers are switched off and the weak pull resistors are active. External pull resistors must be used to define the signal

levels during idle phases.

Note: The transmission window may be different for each channel.

TTP Asynchronous Bus Interface

When in asynchronous mode of operation the channel's bus unit uses a self-clocking transmission encoding which can

be either MFM or Manchester at a maximum data rate of 5 Mbit/s on a shared media (physical bus). The pins can

either be connected to drivers using recessive/dominant states on the wire as well as drivers using active push/pull

functionality.

The RxD signal uses '1' as the inactivity level. In the so-called RS485 compatible mode longer periods of '0' are treated

as inactivity. If the RS485 compatible mode is not used, the application must care to drive RxD to '1' during inactivity on

the bus.

Table 11. Bus Interface Connections

Pin Name

Tx inactive

TxD[0]

weak pull-up

CTS[0]

weak pull-down

TxD[1]

weak pull-up

CTS[1]

weak pull-down

Table 12. Asynchronous Bus Interface Connections

Pin Name

Mode

Connect to PHY

Note

TxD[0]

out

TxD

Transmit data channel 0

CTS[0]

out

CTS

Transmit enable channel 0

TxCLK[0]

in

No function (do not connect)

RXER[0]

in

No function (do not connect)

RXCLK[0]

in

No function (do not connect)

RxDV[0]

in

No function (do not connect)

RxD[0]

in

RxD

Receive data channel 0

TxD[1]

out

TxD

Transmit data channel 1

CTS[1]

out

CTS

Transmit enable channel 1

TxCLK[1]

in

No function (do not connect)

RXER[1]

in

No function (do not connect)

RXCLK[1]

in

No function (do not connect)

RxDV[1]

in

No function (do not connect)

RxD[1]

in

RxD

Receive data channel 1