ATA6602-PLQW ATMEL [ATMEL Corporation], ATA6602-PLQW Datasheet - Page 112

• Manufacturer Part Number: ATA6602-PLQW
• Description: Microcontroller with LIN Transceiver, 5V Regulator and Watchdog
• Manufacturer: ATMEL [ATMEL Corporation]

4.12.3
112
ATA6602/ATA6603
Counter Unit
The main part of the 8-bit Timer/Counter is the programmable bi-directional counter unit.
4-28
Figure 4-28. Counter Unit Block Diagram
Signal description (internal signals):
Depending of 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) and the WGM02 bit located in the Timer/Counter
Control Register B (TCCR0B). There are close connections between how the counter behaves
(counts) and how waveforms are generated on the Output Compare outputs OC0A and OC0B.
For more details about advanced counting sequences and waveform generation (see
Operation” on page
The Timer/Counter Overflow Flag (TOV0) is set according to the mode of operation selected by
the WGM02:0 bits. TOV0 can be used for generating a CPU interrupt.
shows a block diagram of the counter and its surroundings.
count
direction
clear
clk
top
bottom
Tn
T0
is present or not. A CPU write overrides (has priority over) all counter clear or
DATA BUS
TCNTn
115).
Increment or decrement TCNT0 by 1.
Select between increment and decrement.
Clear TCNT0 (set all bits to zero).
Timer/Counter clock, referred to as clk
Signalize that TCNT0 has reached maximum value.
Signalize that TCNT0 has reached minimum value (zero).
T0
). clk
T0
can be generated from an external or internal clock source,
direction
count
clear
bottom
Control Logic
top
TOVn
(Int.Req.)
clk
Tn
T0
in the following.
Clock Select
(From Prescaler)
Detector
Edge
4921C–AUTO–01/07
“Modes of
Tn
Figure