Qualcomm GSP-1620 specifications Port Arbitration Behavior

Developing Modem Applications

•Control port only — only AT commands can be sent to modem (no data).

•Data and Control ports — the DTE can receive data on the Data port and, at the same time, communicate with the modem on the Control port using AT commands.

The different Data and Control port configurations above are based on which ports are defined as active:

•A port is active if DTR is asserted on that port.

•A port is inactive if DTR is de-asserted on that port.

Using both the Data and Control ports allows more sophisticated communication with the modem and thus better control of it, but requires that you understand the modem’s port arbitration behavior.

Note	In this context, port configuration refers to which ports on the GSP-1620
	modem are active, rather than to port baud rate, parity, etc.

Port Arbitration Behavior

This section describes the modem port arbitration behavior for each of the following port configurations:

•Data port active only

•Control port active only

•Both Data and Control ports active

When a port configuration change occurs due to a DTR change, the AT command configuration parameters maintained by the AT command processor are not modified or reset to their default values. The parameters’ current state will be associated with the newly activated port when the change occurs. An AT command in progress when DTR changes will be silently aborted.

Table 5-3 summarizes modem port arbitration behavior.

80-99208-1 Rev. D 5-9