TMP86FM48 Datasheet, PDF (89/205 Pages) Toshiba Semiconductor – 8 Bit Microcontroller

TMP86FM48
(3) Capture mode
In this mode, the pulse width, period and duty of the TC3 pin input are measured in
this mode, which can be used in decoding the remote control signals or distinguishing
AC 50/60 Hz, etc.
Once command operation has started, the counter free-runs on an internal source
clock.
When the falling edge of the TC3 pin input is detected, the counter value is loaded
into TC3DRB. When the rising edge is detected, the counter value is loaded into
TC3DRA, and the counter is cleared, generating an INTTC3 interrupt.
If the rising edge is detected right after command operation has started, no capture
to TC3DRB and an INTTC3 interrupt occurs only on capture to TC3DRA. If a read
instruction is executed for TC3DRB, the value that exists at the end of the previous
capture (Immediately after a reset, “FF”) is read.
The minimum acceptable input pulse width is equal to the length of one source clock
period selected by TC3CR<TC3CK>.
Table 2.9.3 Capture Input Edges
Capture into
TC3DRB
Capture into
TC3DRA
INTTC3 Interrupt
Falling edge
Rising edge
When the overflow occurs before detecting the edge, the INTTC3 interrupt is
generated, setting “FFH” to TC3DRA and clearing the counter. It is possible to confirm
whether the overflow has occurred or not by reading TC3DRA in interrupt routine.
After generating of interrupt, the capture function and overflow detection stop until
the TC3DRA is read, but the counting is continued. Because the capture function and
overflow detection are restarted by reading TC3DRA, read the TC3DRB before the
reading TC3DRA.
86FM48-87
2007-08-24