ST75C540 datasheet(65/84 Pages) STMICROELECTRONICS

65 / 84 page

XI - TRANSMITTING DATA IN PARALLEL MODE (continued)

XI.1.5 - FSK Full Duplex Mode

In FSK Full duplex Mode the parallel mode as-

sumes that the Bit time duration is the nominal Bit

rate.

Each bit element from the Transmit buffer is main-

tained during the full bit time.

The Nominal bit clock is defined as follows :

FSK Standard

Nominal Transmit Bit Rate (Hz) (1)

V.21

300

Bell 103

300

V.23 Originate

V.23 Answer

1200

Note 1 :

T he accur acy of the B i t cl ock is given by t he

ST75C530/540 oscillator, and must better than 100ppm.

XI.2 - Modem Flow Chart

When Data Mode, each time the ST75C530/540

need a bit to transmit it executes the following

routine (see Figure 28). Where x starts with the

value 0 and toggle thereafter between 1 and 0.

XI.3 - Host Flow Chart

Here after are Flowcharts to :

- Establish a V.29 transmission

- Send Synchronous continuous “$AA, $55, $AA,

$55, ...” sequence.The managmentof the Buffers

are done under Interrupt.

- Stop properly the transmition.

Yes

BEGIN

READ BIT IN

INTERNAL BUFFER

EMPTY

SELECT NEXT DUAL

RAM BUFFER X

Yes

DTTBSx = 0

MOVE DTTBFx DATA

TO INTERNAL BUFFER

CLEAR DTTBSx

RAISE IT2 INTERRUPT

RETURN

SIGNAL ERROR

INTO ERR_TX

RAISE IT0 INTERRUPT

SELECT DUAL

RAM BUFFER x = 0

RETURN

Figure 28

Establish a V.29 transmition and send the very first

Buffer (see Figure 29).

CONF 0F 08 00 01

HSHK

Yes

STA_106 = 1

FORM 00 (opt)

XMIT 1

FILL FIRST BUFFER

Select V.29 9600bps

Start V.29 sequence

Wait until end

of training

Format synchronous

Fill the first buffer # 0

Start to transmit

the first buffer

FILL FIRST BUFFER

WRITE AA, 55 ...

INTO DTTBF [0..7]

WRITE 08 INTO DTTBFS0

SELECT NEXT BUFFER

IBUF = 1

Tx_COMPLETED = FALSE

ENABLE IT2

ITMASK = 0 x 84

RET

Subroutine :

Figure 29

ST75C530 - ST75C540

65/84

ST75C540 数据表(PDF) 65 Page - STMicroelectronics

ST75C540 数据表(HTML) 65 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84

数据表下载