SARA-R4/N4 series - AT Commands Manual
UBX-17003787 - R09
10 V24 control and V25ter
Page 98 of 307
Application to XON/XOFF flow control implementation in the module
The flow control characters DC1 and DC3 appears at arbitrary locations in the data stream received by the
module. The module with software flow control active during a PPP session, discards these characters after
modifying the flow control state (stopping or starting its own transmit process) and does not include them in
any part of the received data or CRC calculation; in the transmitted data the module escapes the XON/XOFF
characters if they appear in the transmitted PPP frame. They are transmitted on the link as follows:
0x11 is encoded as 0x7d, 0x31. (XON)
0x13 is encoded as 0x7d, 0x33. (XOFF)
PPP ACCM negotiation in the module firmware is implemented in the following way:
• If the XON/XOFF flow control is active on the UART when the PPP is invoked, the requested ACCM is
0x000A0000
• If the XON/XOFF flow control is not active on the UART when the PPP is invoked, the requested ACCM is
0x00000000
As soon as the LCP configuration phase is completed, the IPCP protocol (the network control protocol for
establishing and configuring Internet Protocol over a Point-to-Point Protocol link) can start; from this point
forward the negotiated ACCM are applied.
If SW flow control is enabled on the module, but the DTE requests a wrong ACCM setting (ACCM differs than
0x0A0000) the SW flow control is anyway effective during the data mode, that is the 0x11 and 0x13 is detected
during data mode even if the ACCM is not properly set by the DTE during LCP configuration.
10.6 DTE-DCE character fICF
+ICF
SARA-R404M SARA-R410M-01B SARA-R410M-02B SARA-R410M-52B SARA-R412M
Modules
SARA-N4
Syntax
PIN required
Settings saved Can be aborted
Response time Error reference
Attributes
partial
No
No
-
10.6.1 Description
Sets the local serial port start-stop (asynchronous) character framing which is used in information interchange
between DCE and DTE. Value 0 corresponds to the auto-detect case (if autobauding is supported).
The following restrictions must be reminded:
• If a data frame format refers to a frame without parity (ex. Format 3), the command is accepted, but
the parity value is ignored; it is returned by the AT+ICF read command (and displayed by
) but
it has no meaning
• The command setting is ignored when the AT command interface runs on the USB or on the SPI
interface
10.6.2 Syntax
Type
Syntax
Response
Example
Set
AT+ICF=[<format>[,<parity>]]
OK
AT+ICF=3,1
OK
Read
AT+ICF?
+ICF: <format>,<parity>
OK
+ICF: 3,1
OK
Test
AT+ICF=?
+ICF: (list of supported <format>s),
(list of supported <parity>s)
OK
+ICF: (0-3,5),(0-1)
OK
10.6.3 Defined values
Parameter
Type
Description
<format>
Number
•
0: auto detect
•
1: 8 data 2 stop
