ATMEGA163 ATMEL [ATMEL Corporation], ATMEGA163 Datasheet - Page 49

• Manufacturer Part Number: ATMEGA163
• Description: 8-bit Microcontroller with 16K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

1142E–AVR–02/03
Table 15. Timer TOP Values and PWM Frequency
As shown in Table 15, the PWM operates at either 8, 9, or 10 bits resolution. Note the
unused bits in OCR1A, OCR1B, and TCNT1 will automatically be written to zero by
hardware. For example, bit 9 to 15 will be set to zero in OCR1A, OCR1B, and TCNT1 if
the 9-bit PWM resolution is selected. This makes it possible for the user to perform read-
modify-write operations in any of the three resolution modes and the unused bits will be
treated as don’t care.
Table 16. Timer TOP Values and PWM Frequency
Table 17. Compare1 Mode Select in PWM Mode
Note:
Note that in the PWM mode, the 8, 9, or 10 least significant OCR1A/OCR1B bits
(depending on 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 35 and Figure 36 for an example in each mode.
CTC1
CTC1
0
0
0
0
1
1
1
1
0
0
0
1
1
1
PWM Resolution
1. X = A or B
COM1X 1
PWM11
0
0
1
1
0
0
1
1
10-bit
0
1
1
0
1
1
8-bit
9-bit
COM1X 0
PWM10
1
0
1
1
0
1
0
1
0
1
0
1
0
1
Effect on OCX1
Not connected
Not connected
Cleared on Compare Match, up-counting. Set on Compare
Match, down-counting (non-inverted PWM).
Cleared on Compare Match, down-counting. Set on
Compare Match, up-counting (inverted PWM).
Not connected
Not connected
Cleared on Compare Match, set on overflow.
Set on Compare Match, cleared on overflow.
PWM Resolution
10-bit
10-bit
8-bit
9-bit
8-bit
9-bit
Timer TOP Value
$03FF(1023)
$00FF (255)
$01FF (511)
(1)
Timer TOP Value
$03FF(1023)
$03FF(1023)
$00FF (255)
$01FF (511)
$00FF (255)
$01FF (511)
ATmega163(L)
Frequency
f
f
f
TC1
TC1
TC1
Frequency
f
f
f
/1022
/2046
f
TCK1
TCK1
f
f
TCK1
/510
TCK1
TCK1
TCK1
/1022
/2046
/1024
/510
/256
/512
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