RM0319 datasheet(251/368 Pages) STMICROELECTRONICS

251 / 368 page

RM0319

Fast infrared port (IRDA)

Doc ID 022640 Rev 3

251/368

At last, for each FIR symbol two bits are transmitted: the symbol rate is then one half of the

bit rate, and the baud rate generation unit has to create a unique symbol rate of fen_symb = 2

MHz (being a bit rate of 4 Mbps). Since the pulse duration is a quarter of the symbol

duration for FIR transmission (like MIR), the baud rate generation unit has to create a pulse

rate of fen_pulse = 4* fen_symb.

Table 71 provides a list of the settings of K, L and (N+1) parameters in case of SIR, MIR and

FIR (and with firda_clk = 48 MHz).

19.3.6

FIFO unit

The FIFO unit allows to control the data transfer between peripheral and system memory,

and to buffer the reception and the transmission data.

In particular, data can be transmitted by writing to the transmission buffer register

(IrDA_TXB), which represent the head of the FIFO, and can be read out from the reception

buffer register (IrDA_RXB, which is the tail of the FIFO.

An 8-stage 32-bit shift register is used as buffer. This allows that data can be transferred at

full speed using DMA burst transfers.

Note:

Since IrDA supports only half-duplex communication, one buffer is used for both

transmission and reception.

The FIrDA controller generates the following request signals to control the data transfer to

and from memory.

Table 71.

Settings of K,L and (N+1) parameters for SIR,MIR and FIR in baud rate

generation unit

Bit rate [Kbps]

fen_pulse [kHz]

fen_symb [kHz]

N+1

SIR

9.6

576

9.6

250

19.2

576

19.2

250

38.4

576

38.4

250

57.6

576

57.6

250

115.2

576

115.2

250

MIR

576

2304

576

125

1152

4608

1152

125

FIR

4000

8000

2000

Table 72.

Request signals

Signal

Description

BREQ_INT

Burst request signal. Request a transfer of a programmed burst of words.

LBREQ_INT

Last burst request signal. Request a last burst transfer.

SREQ_INT

Single request signal. Request a transfer of a single word.

LSREQ_INT

Last single request signal. Request a last single transfer.

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