MPC563XM Reference Manual, Rev. 1
1322
Freescale Semiconductor
Preliminary—Subject to Change Without Notice
29.5.2.3
Current Timer Value Register (CVAL)
These registers indicate the current timer position. In the case of the RTI, this will show a value which is
several cycles old, since it originates from a potentially different clock domain.
Offset channe 0x00
Access: Read/Write
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
R
TSV31 TSV30 TSV29 TSV28 TSV27 TSV26 TSV25 TSV24 TSV23 TSV22 TSV21 TSV20 TSV19 TSV18 TSV17 TSV16
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
R
TSV15 TSV14 TSV13 TSV12 TSV11 TSV10 TSV9
TSV8
TSV7
TSV6
TSV5
TSV4
TSV3
TSV2
TSV1
TSV0
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Figure 29-3. Timer Load Value Register (LDVAL)
Table 29-4. LDVAL Field Descriptions
Field
Description
TSV
n
Time Start Value Bits. These bits set the timer start value. The timer will count down until it reaches
0, then it will generate an interrupt and load this register value again. Writing a new value to this
register will not restart the timer, instead the value will be loaded once the timer expires. To abort the
current cycle and start a timer period with the new value, the timer must be disabled and enabled
again (see
).
NOTE: For the RTI, the timer should not be set to a value lower than 32 cycles, otherwise interrupts
may be lost, as it takes several cycles to clear the RTI interrupt. For the other timers, this limit does
not apply, however there will be practical limits, since the processor will require several cycles to
service an interrupt.