8.2.1.1. Handshake Tone Detection. Silicon Laboratories Si2493, Si2404, Si2415, Si2434, Si2494, Si2439, Si2457, Si2443

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8.2.1.1. Handshake Tone Detection

Two tone detectors are reconfigured for detection of the 1400Hz and 2300Hz tones. When a valid tone burst is detected the modem reports it to the host DTE in the V.253 event format as follows.

Event

1400 Hz tone burst detected

Modem-to-DTE indication

0x10, 0x63

Remarks

Character pair <DLE><c> is sent to DTE at the end of the valid tone burst.

2300 Hz tone burst detected 0x10, 0x65 Character pair <DLE><e> is sent to DTE at the end of the valid tone burst.

8.2.1.2. Session Example

Step

1

Table 159. Ademco

®

Mode of Operation

DTE-to-Modem Command

ATE0:UAD|40

Modem-to-DTE

Indication

OK

Remarks

Set UAD.6 to enable Ademco mode tone detections.

2

5

6

3

4

AT:UAD&FF7F

AT:R48

AT+FCLASS=8

AT:U181,78,0,0,1C

ATDnnnnnnn

AT+VTD=5;:U48,32

OK

0064

OK

OK

OK

OK

OK

Clear UAD.7 to disable SIA mode.

DTE reads and records what is the normal “tone off” duration for DTMF dialing. This parameter is country dependent. This parameter will be modified for Data Tones transmission later.

Put modem into V.253 voice mode.

Set up 1400 Hz detector to detect 100 msec Handshake tone burst.

Call RECEIVER station

Change DTMF on off time to prepare for Data

Tones transmission.

7

8

Wait for RECEIVER to answer

9

<DLE><c> 1400 Hz tone burst detected i.e. 0x10, 0x63

<DLE><e>

Note: First part of Handshake Tones detected.

2300 Hz tone burst detected i.e. 0x10, 0x65 Note: Second part of Handshake Tones detected.

Since there is a 100 msec silence between the

1400 Hz and 2300 Hz tones, the <DLE><e> message should come nominally 200 msec after the previous <DLE><c> message.

It is the responsibility of the host DTE driver to measure and validate this time period.

242 Rev. 1.41

AN93

10

Table 159. Ademco

®

Mode of Operation (Continued)

AT:U181,334,0,0,12C OK

11 Delay 250 msec before transmitting Data Tones message.

12 AT+VTS=9,9,9,9,1,8,1,*,#,A,0,0,

0,0,0,3

OK

Change 1400 Hz detector to detect 800 ±300 msec tone burst, i.e. Kissoff tone.

Host DTE should adjust this delay so that the following +VTS DTMF transmission will start between

250 to 300 msec after the reception of <DLE><e> above.

First Data Block is transmitted.

Note: Data octets are placed after the “=” and separated by commas.

Note: Host DTE driver must perform these substitutions,

Octet B as *

Octet C as #

Octet D as A

Octet E as B

Octet F as C

Note: OK is sent at end of transmission.

13

14

Wait for Kissoff tone

15

16

AT*Y254:Q83FB 01AF

OK

<DLE><c>

1.25 seconds has elapsed. But modem still has not reported <DLE><c> to DTE

Check to see if start of a Kissoff Tone has been detected?

If 83FB returns a non-zero value (e.g. 01AF as illustrated here) it means the start of Kissoff tone is detected. Modem will send <DLE><c> to DTE after it has verified that the Kissoff Tone burst duration is valid.

Acknowledgement from RECEIVER detected.

Note: <DLE><c> is sent at end of tone burst.

17 Delay 250 msec before sending next Data Tone Message.

18

19

Repeat from STEP (12) for sending more Data Codes

ATH

AT:U48,64

OK

OK

Hang up at end of session.

Restore DTMF parameters to comply with normal dialing requirements.

Repeat from STEP (1) for next call

Rev. 1.41

243