Infineon Technologies TC1728 User Manual page 1132

For single transfers, it is sufficient to use the transmitter interrupt (TIR), 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
least before 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 entirely impossible.
Using the Transmit Buffer Interrupt (TBIR) to reload transmit data provides the time
necessary to transmit a complete frame for the service routine, as TBUF may be
reloaded while the previous data is still being transmitted.
Asynchronous Mode
TBIR
Idle
Synchronous Mode
TBIR
Idle
Figure 17-10 ASC Interrupt Generation
As shown in Figure
indicates the completed transmission. Software using handshake should, therefore, rely
on TIR at the end of a data block to ensure that all data has been transmitted.
User's Manual
ASC, V1.3 2007-11
Asynchronous/Synchronous Serial Interface (ASC)
TIR
TBIR
RIR
TIR
TBIR
RIR
17-10, TBIR is an early trigger for the reload routine, while TIR
TIR
TBIR
RIR
TIR
TBIR
RIR
17-20
TC1728
TIR
Idle
RIR
TIR
Idle
RIR
MCT06209
V1.0, 2011-12