Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
817
Timers—Intel
®
81341 and 81342
12.4.3
Timer Count Register – TCR0:1
The Timer Count Register (TCRx) is a 32-bit register that contains the timer’s current
count. The register value decrements with each timer clock tick. When this register
value decrements to zero (terminal count), a timer interrupt is generated. When
TMRx.reload is not set for the timer, the status bit in the timer mode register (TMRx.tc)
is set and remains set until the TMRx register is accessed.
shows the timer
count register.
The valid programmable range is from 1H to FFFF FFFFH. Avoid programming TCRx to 0
as it has varying results as described in
Section 12.5, “Uncommon TCRX and TRRX
. User software can read or write TCRx whether the timer is
running or stopped. Bit 3 of TMRx determines user read/write control
(
). The TCRx value is undefined after hardware or software reset.
12.4.4
Timer Reload Register – TRR0:1
The Timer Reload Register (TRRx;
) is a 32-bit register that contains the
timer’s reload count. The timer loads the reload count value into TCRx when
TMRx.reload is set (1), TMRx.enable is set (1) and TCRx equals zero.
As with TCRx, the valid programmable range is from 1H to FFFF FFFFH. Avoid
programming a value of 0, as it may prevent TINTx from asserting continuously. (See
Section 12.5, “Uncommon TCRX and TRRX Conditions” on page 820
for more
information.)
User software can access TRRx whether the timer is running or stopped. Bit 3 of TMRx
determines read/write control (
Section 12.4.2.5, “Bits 4, 5 — Timer Input Clock Select
). TRRx value is undefined after hardware or software
reset.
Table 498. Timer Count Register – TCRx
31:00
0000 0000H Timer Count Value — TCRx.d31:0
MMR
CP
28
24
20
16
12
8
4
0
31
rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw
na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na
Attribute Legend:
RV = Reserved
PR = Preserved
RS = Read/Set
RW = Read/Write
RC = Read Clear
RO = Read Only
NA = Not Accessible
Intel XScale
®
processor
Coprocessor address
TCR0: CP6, Page 9, Register 2
TCR1: CP6, Page 9, Register 3
Table 499. Timer Reload Register – TRRx
31:00
0000 0000H Timer Auto-Reload Value — TRRx.d31:0
MMR
CP
28
24
20
16
12
8
4
0
31
rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw
na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na
Attribute Legend:
RV = Reserved
PR = Preserved
RS = Read/Set
RW = Read/Write
RC = Read Clear
RO = Read Only
NA = Not Accessible
Intel XScale
®
processor
Coprocessor address
TRR0: CP6, Page 9, Register 4
TRR1: CP6, Page 9, Register 5