
Asynchronous / synchronous serial interface
UM0404
DocID13284 Rev 2
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.
As shown in the
, S0TBIR is an early trigger for the reload routine, while S0TIR
indicates the completed transmission. Software using handshake therefore should rely on
S0TIR at the end of a data block to make sure that all data has really been transmitted.
Figure 104. ASC0 interrupt generation
Idle
Idle
Star
t
Sta
rt
Sta
rt
Stop
Stop
Stop
S0TBIR
S0TBIR
S0TBIR
S0TIR
S0TIR
S0TIR
S0RIR
S0RIR
S0RIR
Idle
Idle
S0TBIR
S0TBIR
S0TBIR
S0TIR
S0TIR
S0TIR
S0RIR
S0RIR
S0RIR
Asynchronous Mode
Synchronous Mode