ata6616 ATMEL Corporation, ata6616 Datasheet - Page 113

• Manufacturer Part Number: ata6616
• Description: Microcontroller With Lin Transceiver, 5v Regulator And Watchdog
• Manufacturer: ATMEL Corporation

4.11.5
9132A–AUTO–10/08
DRAFT
Output Compare Unit
Depending on the mode of operation used, the counter is cleared, incremented, or decremented
at each timer clock (clk
selected by the Clock Select bits (CS02:0). When no clock source is selected (CS02:0 = 0) the
timer is stopped. However, the TCNT0 value can be accessed by the CPU, regardless of
whether clk
count operations.
The counting sequence is determined by the setting of the WGM01 and WGM00 bits located in
the Timer/Counter Control Register (TCCR0A). There are close connections between how the
counter behaves (counts) and how waveforms are generated on the Output Compare output
OC0A. For more details about advanced counting sequences and waveform generation, see
“Modes of Operation” on page
The Timer/Counter Overflow Flag (TOV0) is set according to the mode of operation selected by
the WGM01:0 bits. TOV0 can be used for generating a CPU interrupt.
The 8-bit comparator continuously compares TCNT0 with the Output Compare Register
(OCR0A). Whenever TCNT0 equals OCR0A, the comparator signals a match. A match will set
the Output Compare Flag (OCF0A) at the next timer clock cycle. If enabled (OCIE0A = 1), the
Output Compare Flag generates an Output Compare interrupt. The OCF0A flag is automatically
cleared when the interrupt is executed. Alternatively, the OCF0A flag can be cleared by software
by writing a logical one to its I/O bit location. The Waveform Generator uses the match signal to
generate an output according to operating mode set by the WGM01:0 bits and Compare Output
mode (COM0A1:0) bits. The max and bottom signals are used by the Waveform Generator for
handling the special cases of the extreme values in some modes of operation
ation” on page
Figure 4-32
Figure 4-32. Output Compare Unit, Block Diagram
T0
shows a block diagram of the Output Compare unit.
is present or not. A CPU write overrides (has priority over) all counter clear or
116).
bottom
FOCn
top
T0
). clk
OCRnx
116.
T0
can be generated from an external or internal clock source,
ATA6616/ATA6617 [Preliminary]
Waveform Generator
WGMn1:0
=
(8-bit Comparator )
DATA BUS
COMnX1:0
TCNTn
OCFnx (Int.Req.)
OCnx
(“Modes of Oper-
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