Terminal DescriptionsUniversal connectorIt is possible to use a resin-based cover for the Universal connector.No. Name Description Specification I/O1 SSW Ext/Int Speaker Switch Input Hi: INT, Low: EXT I2 SP+ BTL Output + for External Speaker Standard load 8 O3 SP- BTL Output – for External Speaker Standard load 8 O4 MSW Ext/Int MIC Switch Input Hi: INT, Low: EXT I5 EMC External MIC Input Impedance: 1.8 k I6 ME External MIC GND – –7 PTT External PTT Input Low: PTT ON I8 PF Programable Function Key Input Input voltage: 0 V - 3.3 V I9 OPT Aux I/O Port (for EXT Option) I: 0 V - 3.3 VO: Standard load 25 k I/O10 E GND GND −11 5V 5V 5V power supply outputMax output current: 140 mA O12 TXD Serial Data Output Baud rate: 115200 bps max O13 RXD Serial Data Input Baud rate: 115200 bps max I14 EMC External MIC input Impedance: 1.8 k IAntenna Terminal50 impedance