Rainbow Electronics AT90S2313 - Manual (Page 29)

29
AT90S2313
0839I–AVR–06/02
Timer/Counter0 Control
Register – TCCR0
• Bits 7..3 – Res: Reserved Bits
These bits are reserved bits in the AT90S2313 and always read zero.
• Bits 2,1,0 – CS02, CS01, CS00: Clock Select0, Bit 2,1 and 0
The Clock Select0 bits 2, 1, and 0 define the prescaling source of Timer/Counter0.
The Stop condition provides a Timer Enable/Disable function. The CK down divided
modes are scaled directly from the CK Oscillator clock. If the external pin modes are
used for Timer/Counter0, transitions on PD4/(T0) will clock the counter even if the pin is
configured as an output. This feature can give the user software control of the counting.
Timer/Counter0 – TCNT0
The Timer/Counter0 is realized as an up-counter with read and write access. If the
Timer/Counter0 is written and a clock source is present, the Timer/Counter0 continues
counting in the timer clock cycle following the write operation.
Bit 7 6 5 4 3 2 1 0
$33 ($53) – – – – – CS02 CS01 CS00 TCCR0
Read/Write R R R R R R/W R/W R/W
Initial value 0 0 0 0 0 0 0 0
Table 7. Clock 0 Prescale Select
CS02 CS01 CS00 Description
0 0 0 Stop, the Timer/Counter0 is stopped.
0 0 1 CK
0 1 0 CK/8
0 1 1 CK/64
1 0 0 CK/256
1 0 1 CK/1024
1 1 0 External Pin T0, falling edge
1 1 1 External Pin T0, rising edge
Bit 7 6 5 4 3 2 1 0
$32 ($52) MSB LSB TCNT0
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial value 0 0 0 0 0 0 0 0