Intel 80C186XL, User Manual

Page: 236 / 405

9-7
TIMER/COUNTER UNIT
Figure 9-5. Timer 0 and Timer 1 Control Registers
Register Name: Timer 0 and 1 Control Registers
Register Mnemonic: T0CON, T1CON
Register Function: Defines Timer 0 and 1 operation.
Bit
Mnemonic
Bit Name
Reset
State
Function
EN Enable 0 Set to enable the timer. This bit can be written only
when the INH bit is set.
INH Inhibit X Set to enable writes to the EN bit. Clear to ignore
writes to the EN bit. The INH bit is not stored; it
always reads as zero.
INT Interrupt X Set to generate an interrupt request when the Count
register equals a Maximum Count register. Clear to
disable interrupt requests.
RIU Register In
Use X Indicates which compare register is in use. When set,
the current compare register is Maxcount Compare B;
when clear, it is Maxcount Compare A.
MC Maximum
Count X This bit is set when the counter reaches a maximum
count.
The MC bit must be cleared by writing to the
Timer Control register. This is not done automati-
cally. If MC is clear, the counter has not reached a
maximum count.
NOTE: Reserved register bits are shown with gray shading. Reserved bits must be written to a
logic zero to ensure compatibility with future Intel products.
15 0
C
O
N
T
A
L
T
E
X
T
R
T
G
M
C
P R
I
U
I
N
T
I
N
H
E
N
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