IR Remote Signal ReceiverIR Remote Signal Receiver OperationPanasonic Semiconductor Development Company MN102H75K/F75K/85K/F85K LSI User Manual218Panasonic8.3 IR Remote Signal Receiver Operation8.3.1 Operating ModesThe IR remote signal receiver has three operating modes: HEAMA, 5-/6-bit, andHEAMA–5-/6-bit automatic detect. Set the mode in the MODAUTO andMODSEL bits of the interrupt control register, RMIR. The FMTMON bit of theinterrupt status register, RMIS, monitors the operating mode.In automatic detect mode, the microcontroller checks the interval betweenremote signal edges. If the interval is (n - 4T S ) to (n + 3T S ), where n is the leadervalue set in the LD[3:0] field of the RMLD register, it processes the data inHEAMA format. If the interval is 28 to 35 TS cycles, it processes the data in5-/6-bit format.8.3.2 Noise FilterThe IR remote signal receiver contains a noise filter to eliminate noise from theremote signal. To enable the noise filter, set the FILTRE bit of the interruptcontrol register, RMIR, to 1. The noise filter samples the remote input signalevery PWM6 cycle (21.3 μs) or PWM8 cycle (85.5 μs), then outputs the valuethat it sampled at least three times during the last four sampling cycles. Thiseliminates any noise occurring during one or two sampling cycles. Select thesampling clock (PWM6 or PWM8) with the SP bit of the RMLD register.(PWM6 is selected at reset.)Figure 8-2 IR Remote Signal Noise FilteringSamplingNoise filteroutputNoise eliminatedRemote signal
