IRCC2.0 Datasheet, PDF (10/87 Pages) SMSC Corporation – Infrared Communications Controller

Consumer IR mode is enabled with the Block
Control Bits in SCE Configuration Register A
(see page 32).
Encoder/Decoder
Tx Enable
SCE
Clock
Carrier Off
Transmit Bit-Rate
Divider
Carrier Frequency
Divider
Receive Bit-Rate
Divider
Rx Enable Sync
Programmable
Receive Carrier
Sense
Range
TV Tx
TV Rx
FIGURE 4 - IrCC 2.0 CONSUMER IR (REMOTE CONTROL) BLOCK
Carrier Frequency Divider
The Carrier Frequency Divider register is used to
program the ASK carrier frequency for the
transmit modulator and receive detector (Figure
5). The divider is eight bits wide.
The input clock to the Carrier Frequency Divider
is 1.6MHz (48MHz ÷ 30). The relationship
between the divider value (CFD) and the carrier
frequency (Fc) is as follows:
CFD = (1.6MHz/Fc) - 1
For example, program the Carrier Frequency
Divider register with 41 ('29'Hex) for a 38kHz TV
Remote: Fc = 38.095kHz. This is ~.25%
accuracy. Table 9 contains representative CFD
vs. Carrier Frequency relationships.
The Carrier Frequency range is 1.6MHz to
6.25kHz.
The carrier frequency encoder/decoder can be
defeated using the Carrier Off bit. When Carrier
Off is one, the transmitter outputs a non-
modulated SCE serial NRZ data stream at the
programmed bit rate; the receiver does not
attempt to demodulate a carrier from the
incoming serial data stream.
10