Tone Generation Function

The Tone Generation function provides up to 32 audible tones informing the user of the operation mode for the current call. The selected tones are not turned on or off, but are simultaneously supplied to the time-division multiplexed (TDM) Switch function (the Tone Generation function does not have an input). The TDM Switch function selects the appropriate tone based on the data it receives from the Processor bus. The TDM Switch function sends this tone signal back to the handset.

For example, when a call has been routed successfully and is waiting for a response, the processor in the POTS card tells the TDM Switch function to select the channel that generates a "ringing" sound. If the other end of the connection is already in use, the processor instructs the TDM Switch function to select the channel that generates a "busy" signal.

The Tone Generation function from AMPP partner NComm, Inc. has a MegaWizard Plug-In, which allows the user to select only the tone parameters required. Using the MegaWizard interface also ensures optimum embedded system block (ESB) usage by calculating the least number of pulse-code modulation (PCM) samples required to generate the tone sequence. The Tone Generation function also supports optional gain control, µ-law, and A-law encoding. The resource utilization summary in this example reflects the instantiation of the NComm function, which includes a dial tone, ring back tones, and a busy signal.