Rainbow Electronics ATmega128RFA1 - Manual (Page 241)

241
8266A-MCU Wireless-12/09
ATmega128RFA1
Register Bits Value Description
0x04 clk_IO/256 (from prescaler)
0x05 clk_IO/1024 (from prescaler)
0x06 External clock source on T0 pin, clock on
falling edge
0x07 External clock source on T0 pin, clock on
rising edge
17.9.4 TCNT0 – Timer/Counter0 Register
Bit 7 6 5 4
$26 ($46) TCNT0_7 TCNT0_6 TCNT0_5 TCNT0_4 TCNT0
Read/Write RW RW RW RW
Initial Value 0 0 0 0
Bit 3 2 1 0
$26 ($46) TCNT0_3 TCNT0_2 TCNT0_1 TCNT0_0 TCNT0
Read/Write RW RW RW RW
Initial Value 0 0 0 0
The Timer/Counter Register gives direct access, both for read and write operations, to
the Timer/Counter0 unit 8-bit counter. Writing to the TCNT0 Register blocks (removes)
the Compare Match on the following timer clock. Modifying the counter (TCNT0) while
the counter is running, introduces a risk of missing a Compare Match between TCNT0
and the OCR0x Registers.
• Bit 7:0 – TCNT0_7:0 - Timer/Counter0 Byte
17.9.5 OCR0A – Timer/Counter0 Output Compare Register
Bit 7 6 5 4
$27 ($47) OCR0A_7 OCR0A_6 OCR0A_5 OCR0A_4 OCR0A
Read/Write RW RW RW RW
Initial Value 0 0 0 0
Bit 3 2 1 0
$27 ($47) OCR0A_3 OCR0A_2 OCR0A_1 OCR0A_0 OCR0A
Read/Write RW RW RW RW
Initial Value 0 0 0 0
The Output Compare Register A contains an 8-bit value that is continuously compared
with the counter value (TCNT0). A match can be used to generate an Output Compare
interrupt, or to generate a waveform output on the OC0A pin.
• Bit 7:0 – OCR0A_7:0 - Output Compare Register