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XC161 Derivatives
Peripheral Units (Vol. 2 of 2)
The General Purpose Timer Units
User’s Manual
14-44
V2.2, 2004-01
GPT_X1, V2.0
Timer Concatenation
Using the toggle bit T6OTL as a clock source for the auxiliary timer in counter mode
concatenates the core timer T6 with the auxiliary timer T5. This concatenation forms
either a 32-bit or a 33-bit timer/counter, depending on which transition of T6OTL is
selected to clock the auxiliary timer.
•
32-bit Timer/Counter: If both a positive and a negative transition of T6OTL are used
to clock the auxiliary timer, this timer is clocked on every overflow/underflow of the
core timer T6. Thus, the two timers form a 32-bit timer.
•
33-bit Timer/Counter: If either a positive or a negative transition of T6OTL is
selected to clock the auxiliary timer, this timer is clocked on every second
overflow/underflow of the core timer T6. This configuration forms a 33-bit timer (16-bit
core timer + T6OTL + 16-bit auxiliary timer).
As long as bit T6OTL is not modified by software, it represents the state of the internal
toggle latch, and can be regarded as part of the 33-bit timer.
The count directions of the two concatenated timers are not required to be the same.
This offers a wide variety of different configurations.
T6, which represents the low-order part of the concatenated timer, can operate in timer
mode, gated timer mode or counter mode in this case.
Figure 14-28 Concatenation of Core Timer T6 and Auxiliary Timer T5
MCA05409
Toggle Latch
T6OUT
T6IRQ
Count
T6R
Core Timer T6
Operating
Mode
Control
BPS2
T6I
Clear
T6IN
f
GPT
Auxiliary
Timer T5
T5I
0
1
MUX
T5I.2
T5IN
T5IRQ
Up/Down
Clear
Up/Down
Count
MUX
T5RC
T5R
T6R
0
1
Edge
Select