AN93
Rev. 1.4
177
6.7.2. Receiving Modem-On-Hold Requests
If modem-on-hold is enabled via the +PMH=1 command, the Si2493 may be placed on hold by a remote modem.
The maximum time the modem will remain on hold is configured with the +PMHT setting. Possible values of
+PMHT are given in Table 121. Upon receipt of a modem-on-hold request, the Si2493 will inPMHR:
followed by the code corresponding to the timeout granted. The DCD pin will be deasserted while the modem is on
hold, and the CONNECT result code will indicate a return to data mode. A modem disconnect due to a timeout or
failed negotiation will result in a NO CARRIER result code.
6.8. HDLC: Bit Errors on a Noisy Line
Bit errors can occur on an impaired line. The problem lies in determining and ignoring the spurious data resulting
from poor line conditions and recovering valid data. This example illustrates a typical data-corruption problem due
to a noisy line and the method used to analyze it. Here, the modem is an Si2404 configured with the following
initialization string after reset.
AT+ES=6,,8
AT+ESA=0,0,0,,1,0
AT+ITF=0383,0128
AT:U87,010A
AT+MS=V22
AT:U7A,12
The following data stream was received over a noisy line.
0D 0A 43 4F 4E 4E 45 43 54 20 31 32 30 30 0D 0A 19 BE 20 20 19 B1 19 B0 19 B2 30 93
19 B1 19 B2 30 93 19 B1 19 B2 30 93 19 B1 19 B2 30 93 19 B1 19 B2 19 B2 B6 9E F7 46
19 B0 19 B2 29 C6 19 B0 19 B2 FF 98 89 18 19 B0 19 B2 92 6E EF 14 65 19 B0 19 B2 DA
BE C6 07 EA D8 31 C2 05 3C FA C8 86 C4 40 E6 19 A0 CA EA A8 F9 19 B2 8D 00 57 A5 43
29 19 B0 19 B2 05 CB 14 9F 7C 2D 19 B0 19 B2 19 B2 19 BA 0D 0A 4E 4F 20 43 41 52 52
49 45 52 0D 0A
Table 117. Possible Responses to PMHR Command from Remote Modem
<Value>
Description
0
Modem-on-hold request denied or not available.
The modem may initiate another modem-on-hold request at a later time.
1
MOH with 10 second timeout granted
2
MOH with 20 second timeout granted
3
MOH with 30 second timeout granted
4
MOH with 40 second timeout granted
5
MOH with 1 minute timeout granted
6
MOH with 2 minute timeout granted
7
MOH with 3 minute timeout granted
8
MOH with 4 minute timeout granted
9
MOH with 6 minute timeout granted
10
MOH with 8 minute timeout granted
11
MOH with 12 minute timeout granted
12
MOH with 16 minute timeout granted
13
MOH with indefinite timeout granted
14
MOH request denied. Future requests in the same session will also be denied.
Содержание Si2404
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Страница 200: ...AN93 200 Rev 1 4 Figure 31 TAM Handset and Speakerphone Voice Paths ...
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Страница 290: ...AN93 290 Rev 1 4 Figure 57 256 Band Spectral Display Figure 58 2048 Band Spectral Display ...
Страница 305: ...AN93 Rev 1 4 305 Figure 76 Parallel or SPI Port Interrupt Service Flowchart ...