ATAR862-3_07 Datasheet, PDF (49/112 Pages) ATMEL Corporation – Microcontroller with UHF ASK/FSK Transmitter

ATAR862-3
22.9.2 Mode 2: 8-bit Compare Counter with 4-bit Programmable Prescaler
Figure 22-11. 8-bit Compare Counter
CL2/1
4-bit counter
RES
POUT
DCG
4-bit compare
CM1
4-bit register
T2D1, 0
8-bit counter
OVF2
RES
CM2
8-bit compare
8-bit register
T2RM
Timer 2
output mode
and T2OTM-bit
T2OTM
T2IM
T2CTM
DCGO
TOG2
INT4
The 4-bit stage is used as programmable prescaler for the 8-bit counter stage. In this mode, a
duty cycle stage is also available. This stage can be used as an additional 2-bit prescaler or for
generating duty cycles of 25%, 33% and 50%. The 4-bit compare output (CM1) supplies the
clock output (POUT) with clocks.
22.9.3 Mode 3/4: 8-bit Compare Counter and 4-bit Programmable Prescaler
Figure 22-12. 4-/8-bit Compare Counter
T2I
SYSCL
CL2/2
DCG
P4CR P41M2, 1 T2D1, 0
OVF2
8-bit counter
RES
CM2
8-bit compare
8-bit register
T2RM
Timer 2
output mode
and T2OTM-bit
T2OTM
T2IM
T2CTM
DCGO
TOG2
INT4
TOG3
T1OUT
SYSCL
SCL
CL2/1
MUX
4-bit counter
RES
CM1
4-bit compare
POUT
T2CS1, 0
4-bit register
In these modes the 4-bit and the 8-bit counter stages work independently as a 4-bit prescaler
and an 8-bit timer with an 2-bit prescaler or as a duty cycle generator. Only in the mode 3 and
mode 4, can the 8-bit counter be supplied via the external clock input (T2I) which is selected via
the P4CR register. The 4-bit prescaler is started via activating of mode 3 and stopped and reset
in mode 4. Changing mode 3 and mode 4 has no effect for the 8-bit timer stage. The 4-bit stage
can be used as prescaler for Timer 3, the SSI or to generate the stop signal for modulator 2 and
modulator 3.
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4556H–4BMCU–07/07