Hytera MD78X, Service Manual

Page: 44 / 519

UHF1 (400
–
470 MHz)
Interface Definition
37
7. Interface Definition
7.1
10-Pin Connector
The 10-pin connector on the front panel is used for audio accessories or data cable connection. The
definition of each pin is described as below.
Pin
No.
Name Type
Signal Electrical
Performance
Description
1
Accessory
identification
interface 1
Digital input 3.3 V CMOS
Pin 1 and Pin 10 (accessory
identifier interface 2) compose
an accessory identification
matrix. Please refer to the
“
10-pin Accessory Identification
Matrix Table ” below for detailed
function definitions.
2 PTT input Digital input 3.3 V CMOS
PTT input for the palm
microphone, which is valid at
low level.
3
External audio
output Analog
output
Load impedance >1 kΩ
Vrms=600mV±10%@1
kHz
60% system max.
deviation
Accessory audio output. When
“Mic Audio Output” is selected
via CPS, this pin will output the
received audio signal.
4 USB_D-
USB data
cable-
USB data
When this pin is used for USB
function, USB function of DB26
will be disabled.
5 GND
Ground
cable
/ /
6 USB_VBUS
USB power
supply Power supply: 5 V; current
limiting: 500 mA
This pin provides power supply
to the USB accessory. It outputs
a 5 V voltage when accessory
identification code is 00|01|10,
and outputs low level when the