AT90CAN128_14 Datasheet, PDF (164/428 Pages) ATMEL Corporation – Non volatile Program and Data Memories

Figure 14-14. Timer/Counter2 Crystal Oscillator Connections
12 - 22 pF
32.768 KHz
12 - 22 pF
TOSC2
TOSC1
GND
A external clock can also be used using TOSC1 as input. Setting AS2 and EXCLK enables this
configuration.
Figure 14-15. Timer/Counter2 External Clock Connections
NC
External
Clock
Signal
TOSC2
TOSC1
For Timer/Counter2, the possible prescaled selections are: clk_T2S/8, clk_T2S/32, clk_T2S/64,
clk_T2S/128, clk_T2S/256, and clk_T2S/1024. Additionally, clk_T2S as well as 0 (stop) may be selected.
Setting the PSR2 bit in GTCCR resets the prescaler. This allows the user to operate with a pre-
dictable prescaler.
14.11.1 General Timer/Counter Control Register – GTCCR
Bit
7
6
5
4
TSM
–
–
–
Read/Write
R/W
R
R
R
Initial Value
0
0
0
0
3
2
1
0
–
–
PSR2 PSR310 GTCCR
R
R
R/W
R/W
0
0
0
0
• Bit 1 – PSR2: Prescaler Reset Timer/Counter2
When this bit is one, the Timer/Counter2 prescaler will be reset. This bit is normally cleared
immediately by hardware. If the bit is written when Timer/Counter2 is operating in asynchronous
mode, the bit will remain one until the prescaler has been reset. The bit will not be cleared by
hardware if the TSM bit is set. Refer to the description of the “Bit 7 – TSM: Timer/Counter Syn-
chronization Mode” on page 98 for a description of the Timer/Counter Synchronization mode.
164 AT90CAN32/64/128
7679H–CAN–08/08