FPGA Registers
EPU-4562 Programmer’s Reference Manual
11
Table 7: TISR – 8254 Timer Interrupt Status Register
Bit
Identifier
Access
Default
Description
7
RESERVED
RO
0
Reserved. Writes are ignored; reads always return 0.
6
RESERVED
RO
0
Reserved. Writes are ignored; reads always return 0.
5
RESERVED
RO
0
Reserved. Writes are ignored; reads always return 0.
4
RESERVED
RO
0
Reserved. Writes are ignored; reads always return 0.
3
RESERVED
RO
0
Reserved. Writes are ignored; reads always return 0.
2
ISTAT_TC5
RW/C
N/A
Status for the 8254 Timer #5 output (terminal count) interrupt
when read. This bit is read-status and a write-1-to-clear.
0 – Timer output (terminal count) has not transitioned from 0 to
a 1 level
1 – Timer output (terminal count) has transitioned from a 0 to a
1 level
1
ISTAT_TC4
RW/C
N/A
Status for the 8254 Timer #4 output (terminal count) interrupt
when read. This bit is read-status and a write-1-to-clear.
0 – Timer output (terminal count) has not transitioned from 0 to
a 1 level
1 – Timer output (terminal count) has transitioned from a 0 to a
1 level
0
ISTAT_TC3
RW/C
N/A
Status for the 8254 Timer #3 output (terminal count) interrupt
when read. This bit is read-status and a write-1-to-clear.
0 – Timer output (terminal count) has not transitioned from 0 to
a 1 level
1 – Timer output (terminal count) has transitioned from a 0 to a
1 level