SI2493-C-FS Silicon Laboratories Inc, SI2493-C-FS Datasheet - Page 208

• Manufacturer Part Number: SI2493-C-FS
• Description: IC ISOMODEM SYSTEM-SIDE 16SOIC
• Manufacturer: Silicon Laboratories Inc

Specifications of SI2493-C-FS

• 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: UART
• Voltage - Supply: 3 V ~ 3.6 V
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AN93
Optimizing the Patch Loading Time
In some cases, patch files may consist of more than
6000 characters. They come in a .txt file containing
multiple lines that need to be sent serially to the
IsoModem. There are several techniques that can be
used in different environments. See the description and
Table 113. Whichever technique is used, it is wise to do
an AT&T6 to verify the CRC of the loaded patch.
Method 1 (The Fastest)
Send the entire file in quiet mode using a program that
waits for a precise amount of time after every line. This
can give load times as short as 0.7 seconds for a
6235 byte patch (at 115 kBaud). The file transfer should
be preceded by a RESET followed by an ATE0 and an
ATQ1. After the transfer, perform an ATE1 and/or ATQ0
if needed:
(1) Low pulse on RESET signal for at least 5.0 ms.
(2) Wait 300 ms
(3) Send ATE0
(4) Wait for an OK
(5) Send ATQ1 to the modem
(6) Wait 0.5 ms
(7) Send AT:PIC (First line of the patch)
(8) Wait 0.5 ms
(n-5) Send AT:PIC0 (Last Line of Patch)
(n-4) Wait 0.5 ms
(n-3) Send ATQ0 to the modem
(n-2) Wait for an OK
(n-1) Send AT&T6 to the modem
( n ) Wait for an OK
208
...
Rev. 0.9
Note that the 0.5 ms wait time is the minimum and may
be tricky in some systems. Also, note that this time
period starts when the last character of a line leaves the
UART TX buffer. Longer wait times, such as 2 ms, may
give adequate load times of 0.925 ms, as shown in
Table 113.
Method 2
Send the entire file using a program that waits for an OK
after every line. This will give 3.98 seconds for a 6235
byte patch (at 115 kBaud). Perhaps longer if the OS has
some latency issues.
Method 3
For development purposes, send the entire patch file
using a program that allows a timed pre-programmed
pause between lines, e.g. HyperTerminal or ProComm.
This will give times of around 16 seconds for a
6235 byte patch (at 115 kBaud).
Due to the time granularity of a typical desktop
operating system, be sure to set the time delay between
lines to 100 ms.