Lucent Technologies MN10285K - Manual (Page 219)

IR Remote Signal Receiver
IR Remote Signal Receiver Operation
Panasonic Semiconductor Development Company MN102H75K/F75K/85K/F85K LSI User Manual
218
Panasonic
8.3 IR Remote Signal Receiver Operation
8.3.1 Operating Modes
The IR remote signal receiver has three operating modes: HEAMA, 5-/6-bit, and
HEAMA–5-/6-bit automatic detect. Set the mode in the MODAUTO and
MODSEL bits of the interrupt control register, RMIR. The FMTMON bit of the
interrupt status register, RMIS, monitors the operating mode.
In automatic detect mode, the microcontroller checks the interval between
remote signal edges. If the interval is (n - 4T
S
) to (n + 3T
S
), where n is the leader
value set in the LD[3:0] field of the RMLD register, it processes the data in
HEAMA format. If the interval is 28 to 35 T
S
cycles, it processes the data in
5-/6-bit format.
8.3.2 Noise Filter
The IR remote signal receiver contains a noise filter to eliminate noise from the
remote signal. To enable the noise filter, set the FILTRE bit of the interrupt
control register, RMIR, to 1. The noise filter samples the remote input signal
every PWM6 cycle (21.3 µs) or PWM8 cycle (85.5 µs), then outputs the value
that it sampled at least three times during the last four sampling cycles. This
eliminates any noise occurring during one or two sampling cycles. Select the
sampling clock (PWM6 or PWM8) with the SP bit of the RMLD register.
(PWM6 is selected at reset.)
Figure 8-2 IR Remote Signal Noise Filtering
Sampling
Noise filter
output
Noise eliminated
Remote signal