CMX624 데이터 시트보기 (PDF) - MX-COM Inc

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CMX624

Bell 202 and V.23 Modem with Call Progress and DTMF

MX-COM Inc  

Bell 202 and V.23 Compatible Modem

14

CMX624 Preliminary Information

Received data from the FSK Demodulator goes into the receive part of the UART block, where it is handled in

one of two ways depending on the setting of Bit 7 of the FSK MODE Register:

1. If the bit is ‘0’ (‘Rx Sync’ mode) then the receive part of the UART block will simply take 8 consecutive bits

from the Demodulator and transfer them to the RX DATA Register (the first bit going into the D0 position).

Note: This mode is intended for detection of simple data patterns such as ‘1010…’ or continuous Mark

or Space signals, the CMX624’s receive data clock extraction circuits are not adequate to support

a true synchronous receive data mode of operation.

2. If Bit 7 of the FSK MODE Register is ‘1’ (‘ Rx Async’) then the received data output of the FSK

Demodulator is treated as 75, 150 or 1200bps asynchronous characters each comprising:

A. A Start bit (Space).

B. 7 or 8 Data bits as determined by Bit 0 of the SETUP Register. These bits will be placed into the

RX DATA Register with the first bit received going into the D0 position.

C. An optional Parity bit as determined by Bits 1 and 2 of the SETUP Register. If Parity is enabled

(Bit 2 of the SETUP Register = ‘1’) then Bit 7 of the FLAGS Register will be set to ‘1’ if the

received parity is incorrect.

D. At least one Stop bit (Mark).

Bit 2 (Rx Data Ready) of the FLAGS Register will be set to ‘1’ every time a new received value is loaded into

the RX DATA Register. If the previous contents of the RX DATA Register had not been read out over the

Serial Bus before the new value is loaded from the UART then Bit 3 (Rx Data Overflow) of the FLAGS

Register will also be set to ‘1’.

Rx FSK signal:

Start D0 D1 D2 D3 D4 D5 D6 D7 P'ty Stop Start D0

RX DATA Register read

Rx Data Ready flag bit:

Rx Data Overflow flag bit:

TTBD

Figure 11: Receive UART Function (Async)

©1999 MX-COM, Inc.

www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054

Doc. # 20480180.108

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