Datasheet

ST10F269 10 - GENERAL PURPOSE TIMER UNIT
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Table 13 : GPT1 Timer Input Frequencies, Resolution and Periods (TQFP144 devices)
Figure 15 : Block Diagram of GPT1
10.2 - GPT2
The GPT2 module provides precise event control
and time measurement. It includes two timers (T5,
T6) and a capture/reload register (CAPREL). Both
timers can be clocked with an input clock which is
derived from the CPU clock via a programmable
prescaler or with external signals. The count
direction (up/down) for each timer is
programmable by software or may additionally be
altered dynamically by an external signal on a port
pin (TxEUD). Concatenation of the timers is
supported via the output toggle latch (T6OTL) of
timer T6 which changes its state on each timer
overflow/underflow.
The state of this latch may be used to clock timer
T5, or it may be output on a port pin (T6OUT). The
overflow / underflow of timer T6 can additionally
be used to clock the CAPCOM timers T0 or T1,
and to cause a reload from the CAPREL register.
The CAPREL register may capture the contents of
timer T5 based on an external signal transition on
the corresponding port pin (CAPIN), and timer T5
may optionally be cleared after the capture
procedure. This allows absolute time differences
to be measured or pulse multiplication to be
performed without software overhead.
The capture trigger (timer T5 to CAPREL) may
also be generated upon transitions of GPT1 timer
T3 inputs T3IN and/or T3EUD. This is
advantageous when T3 operates in Incremental
Interface Mode.
Table 14 GPT2 Timer Input Frequencies,
Resolution and Period (PQFP144 devices) and
Table 15 GPT2 Timer Input Frequencies,
f
CPU
= 32MHz
Timer Input Selection T2I / T3I / T4I
000b 001b 010b 011b 100b 101b 110b 111b
Pre-scaler factor 8 16 32 64 128 256 512 1024
Input Freq 4MHz 2MHz 1MHz 500KHz 250KHz 125KHz 62.5KHz 31.125KHz
Resolution 250ns 500ns 1µs2µs4µs8µs16µs32µs
Period maximum 16.4ms 32.8ms 65.5ms 131ms 262.1ms 524.3ms 1.05s 2.1s
2
n
n=3...10
2
n
n=3...10
2
n
n=3...10
T2EUD
T2IN
CPU Clock
CPU Clock
CPU Clock
T3IN
T4IN
T3EUD
T4EUD
T2
Mode
Control
T3
Mode
Control
T4
Mode
Control
GPT1 Timer T2
GPT1 Timer T3
GPT1 Timer T4
T3OTL
Reload
Capture
U/D
U/D
Reload
Capture
Interrupt
Request
Interrupt
Request
Interrupt
Request
T3OUT
U/D