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XC161 Derivatives
Peripheral Units (Vol. 2 of 2)
The General Purpose Timer Units
User’s Manual
14-38
V2.2, 2004-01
GPT_X1, V2.0
Counter Mode
Counter mode for the core timer T6 is selected by setting bitfield T6M in register T6CON
to 001
B
. In counter mode, timer T6 is clocked by a transition at the external input pin
T6IN. The event causing an increment or decrement of the timer can be a positive, a
negative, or both a positive and a negative transition at this line. Bitfield T6I in control
register T6CON selects the triggering transition (see
Figure 14-24 Block Diagram of Core Timer T6 in Counter Mode
For counter mode operation, pin T6IN must be configured as input (the respective
direction control bit DPx.y must be 0). The maximum input frequency allowed in counter
mode depends on the selected prescaler value. To ensure that a transition of the count
input signal applied to T6IN is recognized correctly, its level must be held high or low for
a minimum number of module clock cycles before it changes. This information can be
found in
Table 14-11 GPT2 Core Timer T6 (Counter Mode) Input Edge Selection
T6I
Triggering Edge for Counter Increment/Decrement
0 0 0
None. Counter T6 is disabled
0 0 1
Positive transition (rising edge) on T6IN
0 1 0
Negative transition (falling edge) on T6IN
0 1 1
Any transition (rising or falling edge) on T6IN
1 X X
Reserved. Do not use this combination
MCB05405
Core Timer T6
Toggle Latch
Up/Down
T6UD
T6IN
T6R
Count
T6OUT
T6IRQ
to T5,
CAPREL
T6I
Clear
T6OUF
Edge
Select