C541U_99 Datasheet, PDF (144/192 Pages) Siemens Semiconductor Group – 8-BIT CMOS MICROCONTROLLER

Interrupt System
C541U
Special Function Register SCF (Address ABH)
MSB
Bit No. 7
6
5
4
3
ABH
–
–
–
–
–
Reset Value : XXXXXX00B
LSB
2
1
0
– WCOL TC SCF
Bit
–
WCOL
TC
Function
Reserved bits for future use.
SSC write collision interrupt flag
WCOL set indicates that an attempt was made to write to the shift register STB
while a data transfer was in progress and not fully completed. Bit WCEN in the
SCIEN register must be set, if an interrupt request will be generated when WCOL
is set.
SSC transfer complete interrupt flag
If TC is set it indicates that the last transfer has been completed. Bit TCEN in the
SCIEN register must be set, if an interrupt request will be generated when TC is
set.
The SSC interrupt is generated by a logical OR of flag WCOL and TC in SFR SCF. Both bits can
be cleared by software when a “0“ is written to the bit location. WCOL is reset by hardware when
after a preceeding read operation of the SCF register the SSC transmit data register STB is written
with data. TC is reset by hardware when after a preceeding read operation of the SCF register the
receive data register SRB is read the next time. The interrupt service routine will normally have to
determine whether it was the WCOL or the TC flag that generated the interrupt, and the bit will have
to be cleared by software.
Semiconductor Group
7-11
1997-10-01