Mux Uart Port Speed; Controlling The Uart Port Speed Within Mux State; Basic Mode Uart Software Flow Control; Advanced Mode Uart Software Flow Control - Motorola G24 Guide Developer's Manual

Appendix B: MUX

MUX UART Port Speed

Auto baud rate detection is disabled in the MUX. To set the UART baud rate, the G24 uses the
<port speed> parameter in +CMUX command. If the parameter is absent, the MUX uses the same
baud rate that was in PREMUX state.

Controlling the UART Port Speed Within MUX State

AT commands such as +CBAUD and +IPR change the virtual baud rate of an IDLC. The
AT+CBAUD? or AT+IPR? commands display the virtual baud rate of the specific IDLC. The
AT+CMUX? command returns the UART baud rate.

Basic Mode UART Software Flow Control

When the G24 enters MUX state or MUX-Init state and the requested mode is Basic, UART
software flow control is disabled. If the AT&K command is set for software flow control, the G24
RS232 serial manager ignores the XON/XOFF characters. When the G24 returns to PREMUX
state, it reads the GRS232CFG AT&K value and acts accordingly.

Advanced Mode UART Software Flow Control

When the G24 enters MUX-Init state and the requested mode is Advanced, UART software flow
control can be used. The G24 acts according to the AT&K value.
Advanced mode ensures that unplanned XOFF/XON characters are not passed inside the MUX
frames by the transparency mechanism.
If the MUX mode is Advanced and AT&K is set for software flow control, the XON/XOFF
characters are detected and removed from the lower layers (UART, serial manager).

Basic Mode MUX Software Flow Control Per Channel

When G24 enters MUX state and the requested mode is Basic, Software Flow Control Per
Channel is enabled.
When G24 MUX virtual channel is not able to receive data, it sends the appropriate MSC
command (according to 3G TS 27.010 V3.3.0), that contains the number of virtual channel that
not able to receive data. If terminal continues to send data to that virtual channel, G24 will buffer
incoming data and deassert CTS (hardware flow control) when the buffer is full.
When G24 MUX virtual channel is ready and able to receive data, it sends the appropriate MSC
command (according to 3G TS 27.010 V3.3.0), that contains the number of virtual channel that
ready to receive data.
If the terminal is not able to receive data (typically because its receive buffer is almost full), it
sends the appropriate MSC command (according to 3G TS 27.010 V3.3.0) with the number of
virtual channel, that not able to receive data. In this case, G24 stops to send data at appropriate
virtual channel. When the terminal is ready and able to receive data, it sends the appropriate MSC
command to G24 (according to 3G TS 27.010 V3.3.0) with the number of virtual channel, to
indicate this.
December 31, 2007 AT Commands Reference Manual B-3