Intel386™ EX EMBEDDED MICROPROCESSOR USER’S MANUAL
D-64
D.66 TMRCON
Timer Control (Control Word Format)
TMRCON Expanded Addr:
ISA Addr:
Reset State:
F043H
0043H
XXH
7 0
SC1 SC0 RW1 RW0 M2 M1 M0 CNTFMT
Bit
Number Bit
Mnemonic Function
7–6 SC1:0 Select Counter:
Use these bits to specify a particular c ounter. The selections you make for
bits 5–0 define this counter’s operation.
00 = coun ter 0
01 = coun ter 1
10 = coun ter 2
11 is not an option for TMRCON’s control word format. Selecting 11
accesses TMRCON’s read-back format, which is shown in Figure 10-29.
5–4 RW1:0 Read/Write Select:
These bits select a read/write option for the counter specified by bits 7–6.
01 =read/wri te least-significant byte only
10 =read/wri te most-significant byte only
11= read/write least-sign ificant byte first, then most-significant byt e
00 is not an option for TMRCON’s control word format. Selecting 00
accesses TMRCON’s counter-latch format, which i s shown in Figure
10-27.
3–1 M2:0 Mode Select:
These bits select an operating mode for the counter specified by bits 7–6.
000= mode 0
001= mode 1
X10= mode 2
X11= mode 3
100= mode 4
101= mode 5
X is a don’t care.
0 CNTFMT Count Format:
This bit selects the count format for the counter specified by bits 7–6.
0 = binary (16 bits)
1 = binary coded decimal (4 decades)