C167CS datasheet(282/517 Pages) INFINEON

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C167CS

Derivatives

The Asynchronous/Synchronous Serial Interface

User’s Manual

11-16

V2.0, 2000-07

Note: Please refer to the general Interrupt Control Register description for an

explanation of the control fields.

Using the ASC0 Interrupts

For normal operation (i.e. besides the error interrupt) the ASC0 provides three interrupt

requests to control data exchange via this serial channel:

• S0TBIR is activated when data is moved from S0TBUF to the transmit shift register.

• S0TIR

is activated before the last bit of an asynchronous frame is transmitted,

or after the last bit of a synchronous frame has been transmitted.

• S0RIR

is activated when the received frame is moved to S0RBUF.

While the task of the receive interrupt handler is quite clear, the transmitter is serviced

by two interrupt handlers. This provides advantages for the servicing software.

For single transfers is sufficient to use the transmitter interrupt (S0TIR), which

indicates that the previously loaded data has been transmitted, except for the last bit of

an asynchronous frame.

For multiple back-to-back transfers it is necessary to load the following piece of data

at last until the time the last bit of the previous frame has been transmitted. In

asynchronous mode this leaves just one bit-time for the handler to respond to the

transmitter interrupt request, in synchronous mode it is impossible at all.

Using the transmit buffer interrupt (S0TBIR) to reload transmit data gives the time to

transmit a complete frame for the service routine, as S0TBUF may be reloaded while the

previous data is still being transmitted.

S0EIC

ASC0 Error Intr. Ctrl. Reg.

SFR (FF70H/B8H)

Reset Value: - - 00H

9876

543210

EIR

EIE

ILVL

GLVL

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rwh

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