102
AT94KAL Series FPSLIC
Rev. 1138G–FPSLI–11/03
Notes:
1. X = A or B
2. x = Don’t care
In the PWM mode, the 8, 9 or 10 least significant OCR1A/OCR1B bits (depends of resolution),
when written, are transferred to a temporary location. They are latched when Timer/Counter1
reaches the value TOP. This prevents the occurrence of odd-length PWM pulses (glitches) in
the event of an unsynchronized OCR1A/OCR1B write. See Figure 56 and Figure 57 for an
example in each mode.
Table 30.
Timer TOP Values and PWM Frequency
CTC1
PWM11
PWM10
PWM Resolution
Timer TOP Value
Frequency
0
0
1
8-bit
$00FF (255)
f
TCK1
/510
0
1
0
9-bit
$01FF (511)
f
TCK1
/1022
0
1
1
10-bit
$03FF(1023)
f
TCK1
/2046
1
0
1
8-bit
$00FF (255)
f
TCK1
/256
1
1
0
9-bit
$01FF (511)
f
TCK1
/512
1
1
1
10-bit
$03FF(1023)
f
TCK1
/1024
Table 31.
Compare1 Mode Select in PWM Mode
CTC1
COM1X1
COM1X0
Effect on OCX1
0
x
Not connected
0
1
0
Cleared on compare match, up-counting. Set on
compare match, down-counting (non-inverted PWM)
0
1
1
Cleared on compare match, down-counting. Set on
compare match, up-counting (inverted PWM)
1
1
0
Cleared on compare match, set on overflow
1
1
1
Set on compare match, set on overflow