Intel 8XC196MC User Manual
9-9
WAVEFORM GENERATOR
9.3.5.1
Center-aligned Modes
In the center-aligned modes, the counter counts down from the WG_RELOAD value to 1, then
counts back up from 1 to WG_RELOAD. When you write to the WG_RELOAD register,
WG_COUNTER is loaded with the reload value. When you set the enable bit in the control reg-
ister, the counter begins counting down and continues counting until it reaches 1, waits one state
time, and starts counting up until it reaches WG_RELOAD. At this point, WG_RELOAD is up-
dated and WG_COUNTER is reloaded with the updated value, so a new reload value takes effect
for the next cycle. The counter resumes counting down from WG_RELOAD to 1. This produces
a symmetrical ascending and descending count, illustrated by the triangular wave in Figure 9-4,
with a period that is twice the WG_RELOAD value. Figure 9-5 shows the operation of outputs
and interrupts in center-aligned modes.
counts back up from 1 to WG_RELOAD. When you write to the WG_RELOAD register,
WG_COUNTER is loaded with the reload value. When you set the enable bit in the control reg-
ister, the counter begins counting down and continues counting until it reaches 1, waits one state
time, and starts counting up until it reaches WG_RELOAD. At this point, WG_RELOAD is up-
dated and WG_COUNTER is reloaded with the updated value, so a new reload value takes effect
for the next cycle. The counter resumes counting down from WG_RELOAD to 1. This produces
a symmetrical ascending and descending count, illustrated by the triangular wave in Figure 9-4,
with a period that is twice the WG_RELOAD value. Figure 9-5 shows the operation of outputs
and interrupts in center-aligned modes.
Figure 9-4. Center-aligned Modes — Counter Operation
In mode 0, the WG_COMPx and WG_OUTPUT registers are updated only once during the car-
rier period, when the counter reaches the reload value. In mode 1, these registers are updated
twice during the carrier period: first when the counter is set to 1, then again when it reaches the
reload value.
rier period, when the counter reaches the reload value. In mode 1, these registers are updated
twice during the carrier period: first when the counter is set to 1, then again when it reaches the
reload value.
A2636-01
WG_COUNTER
Value
WG_COUNTER =
WG_RELOAD
WG_RELOAD
Changed
Changed
Carrier Period
Reset
Write to WG_RELOAD
1
0
Counter
Enabled