手机接脚图
Pin
1
GND
Charger/System Ground
2
V_OUT
Accessory Output Supply. (Min/Typ/Max - 3.4V...10V - Output Current 50mA)
3
XMIC
External Microphone Input and Accessory Identification Identification *TYP/MAX: 8...50 mV(The Maximum Value Corresponds to 0dBm Network Level with input amplifier gain set to 20 dB ,typical value is maximum value -16 dB)
ID
Accessory Identification *1,7...2,05 V Headset Adapter Connected *1,15...1,4 V Compact Handsfree Unit Connected *2.22...2.56 V Infra Red Link Conneceted
4
EXT_RF
External RF Control Input Min/Max: 0...0.5V External RF in use Min/Max: 2.4...3.2V Internal Antenna in use
5
TX
FBUS Transmit *Accessory FBUS Transmit Signal
6
MBUS
Serial Control Bus *Logic Low Level: 0....0.5V *Logic High Level:2.4V....3.2V
7
BENA
Not Connected
8
SGND
Signal Ground
9
XEAR
External Speaker and Mute Control *Min/Typ/Max: 0....32....500 mV (Typical level corresponds to -16 dBM) Network Level with Volume Control in Nominal Position 8dB Below Maximum Maximum 0 dBM Maximum Volume Codec Gain -6dB) Mute ON (HF SPEAKER MUTE ):0...0,5 V d.c. Mute OFF (HF SPEAKER ACTIVE ): 1,0...1,7 V d.c.
10
Hook
Hook Signal *Hook Off (Handset in Use): 0....0.5V *Hook On (Handset in Use): 2.4V....3.2V
11
RX
FBUS Receive *Accessory FBUS Receive Signal
12
V_IN
Charging Supply Voltage (Max 16V)
注: 1.市面上一般可以买到的Maxim232大都是 232CPE(C表工作范围,PE表16Pin DIP包装),所以若要比较高的速度,就要使用1uF的电容,速度可达120Kbps,若使用0.1uF速度就只有64Kbps,若您买到的是Maxim 232ACPE则只要使用0.1uF即可以有200Kbps的速度. 2.Maxim 232的耗电流比较大,大约二对通信埠全用上的话要15ma的电流,因我们只用到一对通信埠所以会小一点,但目前有些电脑及NOTEBOOK的com port都设计成低电压,所以有人用Maxim 232来做就无法正常工作,可改用 Hirris HIN232CP (16Pin DIP包装)耗电流比较小,只要5ma,若再不行可把稳压IC 78L05一起拿掉,接法看下面做法.
自制电路例子(使用Hirris HIN232CB SMT IC) Hirris HIN232CB SMT IC外观
直接把电容及接线焊在IC上
组合图直接把二极管,稳压IC 78L05,电容10uF(SMT)等元件接在母的D型 9Pin RS-232接头(PS.此电路没使用78L05,而直接以5.1V 稽纳二极管及电阻替代),如下图
背视图
以5.1V 稽纳二极管及电阻替代稳压IC 78L05
电路上的两个2.7V 稽纳二极管直接焊在手机接头上,而原免持听筒的线就改为信号线
完成后只会看到手机接头及RS-232接头