ata6616 ATMEL Corporation, ata6616 Datasheet - Page 123

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

4.11.10
9132A–AUTO–10/08
DRAFT
Timer/Counter0 Prescaler
Figure 4-41. Prescaler for Timer/Counter0
The clock source for Timer/Counter0 is named clk
system I/O clock clk
clocked from the XTAL oscillator or XTAL1 pin. This enables use of Timer/Counter0 as a Real
Time Counter (RTC).
A crystal can then be connected between the XTAL1 and XTAL2 pins to serve as an indepen-
dent clock source for Timer/Counter0.
A external clock can also be used using XTAL1 as input. Setting AS0 and EXCLK enables this
configuration.
For Timer/Counter0, the possible prescaled selections are: clk
clk
Setting the PSR0 bit in GTCCR resets the prescaler. This allows the user to operate with a pre-
dictable prescaler.
• During asynchronous operation, the synchronization of the interrupt flags for the
T0S
b) Wait for the corresponding Update Busy Flag to be cleared.
c) Read TCNT0.
asynchronous timer takes 3 processor cycles plus one timer cycle. The timer is therefore
advanced by at least one before the processor can read the timer value causing the setting of
the interrupt flag. The Output Compare pin is changed on the timer clock and is not
synchronized to the processor clock.
XTAL2
XTAL1
/128, clk
T0S
Oscillator
/256, and clk
EXCLK
IO
. By setting the AS0 bit in ASSR, Timer/Counter0 is asynchronously
PSRn
CSn0
CSn1
CSn2
clk
0
1
I/O
T0S
ASn
/1024. Additionally, clk
ATA6616/ATA6617 [Preliminary]
0
1
clk
TnS
Clear
T0S
. clk
T0S
TIMER/COUNTERn CLOCK SOURCE
T0S
as well as 0 (stop) may be selected.
is by default connected to the main
0
10-BIT T/C PRESCALER
clk
T0S
Tn
/8, clk
T0S
/32, clk
T0S
/64,
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