MCP2140A データシートの表示（PDF） - Microchip Technology

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MCP2140A

IrDA® Standard Protocol Stack Controller With Fixed 9600 Baud Communication Rate

Microchip Technology 

MCP2140A

2.5 Encoder/Decoder

The encoder converts the UART format data into the

IrDA Standard format data and the decoder converts

IrDA Standard format data into UART format data.

2.5.1 ENCODER (MODULATION)

The data that the MCP2140A UART received (on the

TX pin) that needs to be transmitted (on the TXIR pin)

is modulated. This modulated signal drives the IR

transceiver module. Figure 2-6 shows the encoding of

the modulated signal.

Note:

The signal on the TXIR pin does not

actually line up in time with the bit value

that was transmitted on the TX pin, as

shown in Figure 2-6. The TX bit value is

shown to represent the value to be

transmitted on the TXIR pin.

Each bit time is comprised of 16-bit clocks. If the value

to be transmitted (as determined by the TX pin) is a

logic-low, the TXIR pin will output a low level for 7-bit

clock cycles, a logic high level for 3-bit clock cycles or

a minimum of 1.6 µs (see Parameter IR121). The

remaining 6-bit clock cycles will be low. If the value to

transmit is a logic-high, the TXIR pin will output a low

level for the entire 16-bit clock cycles.

FIGURE 2-6:

ENCODING

Start Bit

16 CLK

Data bit 0 Data bit 1 Data bit 2 Data bit ...

BITCLK

TX Bit

Value

TXIR

7 CLK

12 Tosc

0

1

0

0

1

0

DS22050A-page 12

© 2007 Microchip Technology Inc.

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