Datasheet

ST10F269 9 - CAPTURE/COMPARE (CAPCOM) UNITS
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9 - CAPTURE/COMPARE (CAPCOM) UNITS
The ST10F269 has two 16 channels CAPCOM
units as described in Figure 12. These support
generation and control of timing sequences on up
to 32 channels with a maximum resolution of
200ns at 40MHz CPU clock on PQFP144 devices
and 250ns at 32MHz CPU clock on TQFP144
devices. The CAPCOM units are typically used to
handle high speed I/O tasks such as pulse and
waveform generation, pulse width modulation
(PMW), Digital to Analog (D/A) conversion,
software timing, or time recording relative to
external events.
Four 16-bit timers (T0/T1, T7/T8) with reload
registers provide two independent time bases for
the capture/compare register array (See Figures
Figure 13 and Figure 14).
The input clock for the timers is programmable to
several prescaled values of the internal system
clock, or may be derived from an overflow/
underflow of timer T6 in module GPT2. This
provides a wide range of variation for the timer
period and resolution and allows precise
adjustments to application specific requirements.
In addition, external count inputs for CAPCOM
timers T0 and T7 allow event scheduling for the
capture/compare registers relative to external
events.
Each of the two capture/compare register arrays
contain 16 dual purpose capture/compare
registers, each of which may be individually
allocated to either CAPCOM timer T0 or T1 (T7 or
T8, respectively), and programmed for capture or
compare functions. Each of the 32 registers has
one associated port pin which serves as an input
pin for triggering the capture function, or as an
output pin to indicate the occurrence of a compare
event. Figure 12 shows the basic structure of the
two CAPCOM units.
Figure 12 : CAPCOM Unit Block Diagram
Pin
Tx
Input
Control
2
n
n = 3...10
GPT2 Timer T6
Pin
TxIN
CPU
Clock
Mode
Control
(Capture
or
Compare)
16
Capture inputs
Compare outputs
Pin
Ty
Input
Control
2
n
n = 3...10
GPT2 Timer T6
Over / Underflow
CPU
Clock
Reload Register TxREL
CAPCOM Timer Tx
Interrupt
Request
Sixteen 16-bit
(Capture/Compare)
Registers
Over / Underflow
CAPCOM Timer Ty
Reload Register TyREL
16
Capture / Compare*
Interrupt Requests
Interrupt
Request
x = 0, 7
y = 1, 8