Rainbow Electronics ATtiny2313 - Manual (Page 82)

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ATtiny2313
2543A–AVR–08/03
the edge detector uses sampling, the maximum frequency of an external clock it can
detect is half the sampling frequency (Nyquist sampling theorem). However, due to vari-
ation of the system clock frequency and duty cycle caused by Oscillator source (crystal,
resonator, and capacitors) tolerances, it is recommended that maximum frequency of an
external clock source is less than f
clk_I/O
/2.5.
An external clock source can not be prescaled.
Figure 38. Prescaler for Timer/Counter0 and Timer/Counter1 (1)
Note: 1. The synchronization logic on the input pins ( T1/T0) is shown in Figure 37.
General Timer/Counter
Control Register – GTCCR
• Bit 0 – PSR10: Prescaler Reset Timer/Counter1 and Timer/Counter0
When this bit is one, Timer/Counter1 and Timer/Counter0 prescaler will be Reset. This
bit is normally cleared immediately by hardware. Note that Timer/Counter1 and
Timer/Counter0 share the same prescaler and a reset of this prescaler will affect both
timers.
PSR10
Clear
clk
T1
clk
T0
T1
T0
clk
I/O
Synchronization
Synchronization
Bit 7 6 5 4 3 2 1 0
— – – – – – — PSR10 GTCCR
Read/Write R R R R R R R/W R/W
Initial Value 0 0 0 0 0 0 0 0