TIR2000 datasheet(21/63 Pages) TI

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2–9

Program the IRCFG[3] bit to select fixed 1.6

µs or 3/16th pulse width

Write a 1 to the ACREG[7] bit to enable data transmission.

Write a 1 to the MCR[3] bit to enable the selected IRQ channel

2.1.3.2

SIR Data Receive Mode

The following register programming steps are required to receive data in SIR mode:

Reset the RX FIFO. This includes:

•

Write the LCR register to set the LCR[7] bit to a 1. The LCR[7] bit must be a 1 in order to be

able to write to the FCR(5) bit.

•

Program the FCR to select 64-/16-bytes RX FIFO register, non-DMA mode of operation,

select the RX FIFO trigger level and to clear the RX FIFO.

•

Write the LCR register so that the LCR[7] bit = 0 (for normal operation).

Program the IER register to enable the receive related interrupts which include:

•

RX threshold interrupt (IER[0]) bit

•

Modem-Status interrupt enable (IER[3])

•

Disable the TX related interrupts (TX FIFO below threshold interrupt and the TX underrun

interrupt).

Write a 1 to the ACREG[6] bit to enable data receive.

2.1.4

SHARP Infrared (IR) mode

The SHARP IR mode of operation is similar to the SIR mode except the modulation/demodulation of the

serial data is different. The SHARP IR mode uses amplitude shift keying (ASK) modulation/demodulation.

Data transfer can take place up to a 38.4K baud rate. In the ASK modulation, a 0 is signaled by sending a

500-kHz continuous pulse and a 1 is signaled by the absence of an IR pulse (see Figure 2–3).

No Pulse

Transmit Data

IR Output

Ir Pulse

No Pulse

Ir Pulse

Figure 2–3. SHARP Ir Encoding

The following register programming steps are required for encoding in the SHARP Ir mode:

Program the ICR register

Program the prescaler (PRESC) register to insure the prescaler output is approximately 1.43

MHz. The default PRESC value is used for an input clock frequency of 48 MHz.

Program the auxiliary baud rate divisor lower byte (ABDL) and the auxiliary baud rate divisor

higher byte (ABDH) registers to select the desired communication baud rate for the UART mode.

The baud rate is given by:

(2)

Baud rate

PRESC

Divisor

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