Tait TM8000 Series Applications Manual

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60 Programmable I/O Lines TM8000 3DK Hardware Developer’s Kit Application ManualSeptember 2003 © Tait Electronics Ltd3.1.17 Force Audio PA OnApplication This input signal is used to activate the audio PA. This action is required toallow any audio on the RX_BEEP_IN line of the internal optionsconnector to be heard from the speaker when no other audio unmuteconditions exist.Configuration Configure an input line and associate it with this action. Set the active state(high or low) and the debounce time (0 to 100ms).Timing When this input line is activated and the audio PA is off, there will be a delayof 50ms before audio PA output is unmuted. This delay prevents undesiredtransient noise (audible ‘pop’) caused by the audio PA powering up. If theaudio PA is already on or there has been speaker audio within 100ms priorto activation there is no significant unmute delay.Description When this input line is activated, the radio unmutes the audio PA. If theaudio PA is already unmuted, no action occurs. If a higher priority mutecondition exists, activation of this line will have no effect.When this input line is deactivated, the audio PA reverts to its previous state.If a higher priority unmute condition exists, deactivation of this line willhave no effect.If the input line is active while the radio is powered up, it must be re-appliedfor the action to be carried out.Related Actions A related ‘Force Audio PA Off’ input signal exists, for which another inputline can be assigned. Separate input lines are needed because deactivation ofeach line should release the corresponding action rather than forcing theaudio PA into the opposite state.The ‘Mute Audio Output Path’ input signal activates the Rx audio pathonly.The ‘Unmute Audio Output Path’ input signal deactivates the Rx audiopath only.Figure 3.8 Force Audio PA on/offRX processing chain mute audio PAvol speakerRX_BEEP_INForce Audio PAon/offaudio tap points(on AUD_TAP_OUT) RX_AUDRx audio pathbeep audio path