434 TMAA02-08 Keypad Microphone TM9100 Service Manual© Tait Electronics Limited August 200516.3 Radio ProgrammingThe radio does not need to be programmed to recognize the presence of akeypad microphone, as this is automatically done when the radio ispowered on.However, there are a few related fields that should be configured, asrequired, to enable the keypad microphone to be used effectively. Forexample, in conventional mode there are check boxes called “Selcall CallDialling”, “DTMF Call Dialling” and “Phone Patch Call Dialling”. Thereis also an option “Conventional Dialling Type” field, where you canprogram the radio to dial labels or channels from the default display.Refer to the online help of the programming application for more informationabout these programming options.16.4 Interface SpecificationThe following table and diagram summarizes the signals used for the keypadmicrophone on the radio’s microphone connector and shows the interfacebetween the keypad microphone and the radio.16.5 Circuit DescriptionThe microphone has a standard 12-key telephone keypad which isconnected to a micro-processor. The micro-processor performs the keypadscanning using eight GPIO lines. When a valid keypress is detected, a serialcommand is sent from the microphone.Table 16.1 Keypad microphone connector - pins and signalsPin Signal Colour Description1 RX audio — not connected2 13.8V black power supply3 TXD green transmit serial data4 PTT white PTT and hookswitch5 MIC blue audio from the microphone6 GND red ground7 RXD yellow receive serial data8 IO — not connected
