CC2510FX Datasheet, PDF (116/253 Pages) List of Unclassifed Manufacturers – True System-on-Chip with Low Power RF Transceiver and 8051 MCU

CC2510Fx / CC2511Fx
13.6 8-bit Timer 3 and Timer 4
Timer 3 and 4 are 8-bit timers which support
typical input capture and output compare
operations using two capture/compare
channels each. The timer allows general-
purpose timer and waveform generation
functions.
Features of Timer 3/4 are as follows:
• Dual channel operation
• Rising, falling or any edge input compare
• Set, clear or toggle output compare
• Free-running, modulo or up/down counter
operation
• Clock prescaler for divide by 1, 2, 4, 8, 16,
32, 64, 128
• Interrupt request generated on each
capture/compare and terminal count event
• DMA trigger function
13.6.1 8-bit Timer Counter
All timer functions are based on the main 8-bit
counter found in Timer 3/4. The counter
increments or decrements at each active clock
edge. The period of the active clock edges is
defined by the register bits CLKCON.TICKSPD
which is further divided by the prescaler value
set by TxCTL.DIV (where x refers to the
timer number, 3 or 4). The counter operates as
either a free-running counter, a down counter,
a modulo counter or as an up/down counter.
It is possible to read the 8-bit counter value
through the SFR TxCNT where x refers to the
timer number, 3 or 4.
The possibility to clear and halt the counter is
given with TxCTL control register settings. The
counter is started when a 1 is written to
TxCTL.START. If a 0 is written to
TxCTL.START the counter halts at its present
value.
13.6.2 Timer 3/4 Mode Control
In general the control register TxCTL is used
to control the timer operation. The timer
modes are described in the following sections.
13.6.2.1 Free-running Mode
In the free-running mode of operation the
counter starts from 0x00 and increments at
each active clock edge. When the counter
reaches 0xFF the counter is loaded with 0x00
and continues incrementing its value. When
the terminal count value 0xFF is reached (i.e.
an overflow occurs), the interrupt flag
TIMIF.TxOVFIF is set. If the corresponding
interrupt mask bit TxCTL.OVFIM is set, an
interrupt request is generated. The free-
running mode can be used to generate
independent time intervals and output signal
frequencies.
Figure 21 Free-running Mode
13.6.2.2 Down mode
In the down mode, after the timer has been
started, the counter is loaded with the contents
in TxCC. The counter then counts down to
0x00 and remains at 0x00. The flag
TIMIF.TxOVFIF is set when 0x00 is reached.
If the corresponding interrupt mask bit
TxCTL.OVFIM is set, an interrupt request is
generated. The timer down mode can
generally be used in applications where an
event timeout interval is required.
CC2510Fx/CC2511Fx PRELIMINARY Data Sheet (Rev. 1.2) SWRS055A Page 116 of 252