SI2493-C-GT Silicon Laboratories Inc, SI2493-C-GT Datasheet - Page 210

• Manufacturer Part Number: SI2493-C-GT
• Description: IC ISOMODEM SYSTEM-SIDE 24TSSOP
• Manufacturer: Silicon Laboratories Inc

Specifications of SI2493-C-GT

• Mfg Application Notes: SI2493/57/34/15/04, Appl Note AN93
• Data Format: V.21, V.22, V.23, V.29, V.32, V.34, V.90, V.92, Bell 103, Bell 212A
• Baud Rates: 56k
• Interface: Parallel
• Voltage - Supply: 3 V ~ 3.6 V
• Mounting Type: Surface Mount
• Package / Case: 24-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AN93
A V29FastPOS Sample Program
Introduction
The 0.8 revision of AN93 outlined a Fax-Class 1
interface to V.29 FastPOS. In this method, the HDLC
layer is assumed to be accomplished by host software.
Another issue that has been raised is the case where
the EPOS Terminal is calling a server that can answer
either as V.29 FastPOS or V.22bis; it is not possible for
the modem to “train down” to V.22bis.
To address these issues, a new interface has been
designed and implemented as a patch to the Rev C
revision of the Isomodem. This interface allows the call
to start as a V.29 FastPOS and can train down to
V.22bis if the server NAC can answer as either a
V.29FastPOS or V.22bis. Currently, the latest patch is
the rc_p71_bcd8. Please contact Silicon Laboratories,
Inc. for the latest patch.
One of the improved aspects of this interface technique
is to use two control lines: (RTS* and DTR*); RTS*
controls direction of transfer, while the DTR* hangs up
the line. Note that the tradeoff here is that RTS* can no
longer be used as a method of stopping the modem
from sending data to the host. This is generally not an
issue as long as the DTE rate is greater than the DCE
rate and the host can keep up with the receiver without
having to resort to the negation of RTS*.
The data is in V80 format. Just read and write data while
toggling RTS* as needed. Assert RTS* to transmit and
de-assert to receive.
paradigm.
The description here shows how to set up and use the
modem for V29FastPOS and also provides a sample
program along with both a DTE trace and WAV files that
capture what is happening at both ends of the modem.
The only critical signals that are not recorded below but
obviously controlled in the program are the RTS* and
DTR* lines.
The hardware used was the Engineering Eval. Board
Rev 3.2 and a 24xx2G-DC Rev 1.2 module containing a
24 pin 2457 Rev C IsoModem chip plus a 3018 DAA
chip. JP6 was strapped {1-2, 4-5, 7-8, 10-11, 13-14}.
JP5 was unstrapped.
Setup procedure:
1. Host DTE Rate must be greater than 19200.
2. Host DTE must be configured for 8N1 CTS-only flow
3. Load Patch "rc_p71_bcd8.txt"
210
AT+GCI=xxxxxxx
control
We call this a push-to-talk
Rev. 0.9
4. Make Sure RTS* is negated (voltage high)
5. Make Sure DTR* is asserted (voltage low)
6. Send ATDT###
Notes:
AT&D2
AT+IFC=0,2
AT:U87,050A
AT\N0
AT+FCLASS=1
AT:U7A,1
AT:UAA,8004
AT+ES=6,,8
AT+ESA=0,0,0,,1
1.
2.
3.
4.
5.
6. Data to/from the modem is expected to be in V.80
Patch is "Originate Only"
RTS* is used as DIRECTION of transfer. Think
"Push-to-Talk" paradigm. Assert RTS* PRIOR to
transmission. Negate RTS* after frame has been
sent. The modem will guarantee that the carrier is
turned off after all current frames have been
completed.
DTR* is assumed to be connected to the ESC pin
of the modem. It has been programmed to HANG
UP when DTR* is negated.
When the modem is in RECEIVE operation
(RTS* negated), it is not possible to communicate
with the modem. The only control is to hang up
using DTR*.
The modem "automatically" takes care of figuring
out if it is supposed to be in "V29 Long Train" vs.
"V29 Short Train". The primary host responsibility
is to take care of RTS*.
format.
Enables escape pin
Flow control setup
V80 Setup
Wire Mode
Synch access mode
Synch access mode control