Register Description For The 82C53 (Pci-Dio-96, Pxi-6508 Only; Figure B-3. Control Word Format For The 82C53 - National Instruments PCI-DIO-96 User Manual

Register Description for the 82C53 (PCI-DIO-96, PXI-6508 Only)

Figure B-3 shows the control word format used to program the 82C53. Bits 7 and 6 of the
control word select the counter to be programmed. Bits 5 and 4 select the mode by which the
count data is written to and read from the selected counter. Bits 3, 2, and 1 select the mode for
the selected counter. Bit 0 selects whether the counter counts in binary or BCD format. After
writing to the Configuration Register to configure a counter, you can read or write the counter
itself eight bits at a time, as controlled by the access mode.
Counter Select
00 = Counter 0
01 = Counter 1
10 = Counter 2
11 = Illegal
Access Mode
00 = Latch counter value
01 = Access LSB only
10 = Access MSB only
11 = Access LSB, then MSB
© National Instruments Corporation
Appendix B
D7 D6 D5 D4

Figure B-3. Control Word Format for the 82C53

Register-Level Programming — Register Map and Description
D3 D2 D1 D0
B-9 PCI-DIO-96/PXI-6508/PCI-6503 User Manual
BCD
1 = Count in BCD
0 = Count in Binary
Mode Select
000 = Mode 0
001 = Mode 1
010 = Mode 2
011 = Mode 3
100 = Mode 4
101 = Mode 5
110 = Mode 2
111 = Mode 3