MCP2140-I/SSRVB Microchip Technology, MCP2140-I/SSRVB Datasheet - Page 12

• Manufacturer Part Number: MCP2140-I/SSRVB
• Description: 9600 BAUD FIXED SPEED IRDA PROTOCOL HANDLER & BIT ENCODER/DECODER, -40C to +85C, 20-SSOP 208mil, TUBE
• Manufacturer: Microchip Technology

MCP2140
2.5.2
The modulated signal (data) from the IR transceiver
module (on RXIR pin) needs to be demodulated to
form the received data (on RX pin). Once demodula-
tion of the data byte occurs, the data that is received is
transmitted by the MCP2140 UART (on the RX pin).
Figure 2-6
signal.
Each bit time is comprised of 16-bit clocks. If the value
to be received is a logic-low, the RXIR pin will be a low
level for the first 3-bit clock cycles, or a minimum of
1.6 µs. The remaining 13-bit clock cycles (or difference
up to the 16-bit clock time) will be high. If the value to
be received is a logic-high, the RXIR pin will be a high
level for the entire 16-bit clock cycles. The level on the
RX pin will be in the appropriate state for the entire 16
clock cycles.
FIGURE 2-6:
DS21790A-page 12
Note:
RXIR Bit Value
RXPDREF
BITCLK
(CLK)
RXPD
RX
The signal on the RX pin does not actually
line up in time with the bit value that was
received on the RXIR pin, as shown in
Figure
represent the value to be transmitted on
the RX pin.
DECODER (DEMODULATION)
shows the decoding of the modulated
2-6. The RXIR bit value is shown to
Start Bit
16 CLK
16 CLK
DECODING
0
1.6 µs (up to 3 CLK)
Data bit 0
16 CLK
13 CLK
1
Data bit 1
16 CLK
Preliminary
0
Data bit 2
2.6
The baud rate for the MCP2140 IR port (the TXIR and
RXIR pins) is fixed at the default rate of 9600 baud. The
Primary device will be informed of this parameter dur-
ing NDM. The Host UART baud rate and the IR port
baud rate are the same.
16 CLK
0
IR Port Baud Rate
Data bit ...
16 CLK
1
2003 Microchip Technology Inc.
16 CLK
0