Kenwood NX-200 Service Manual page 38

NX-200
6-1. ASIC
The ASIC (IC108) is a 32-bit RISC processor, equipped
with peripheral function and ADC/DAC.
This ASIC operates at 18.432MHz clock and 3.3V /1.5V
DC. It controls the fl ash memory, SRAM, DSP, the receive
circuit, the transmitter circuit, the control circuit, and the dis-
play circuit and transfers data to or from an external device.
6-2. Memory Circuit
The memory circuit consists of the ASIC (IC108) and the
SRAM (IC103) and fl ash memory (IC101). The fl ash memory
has capacity of 32M-bit that contains the transceiver control
program for the ASIC and stores the data. It also stores the
data for transceiver channels and operating parameter that
are written by the FPU. This program can be easily written
from external devices. The SRAM has capacity of 1M-bit
that contains work area and data area.
■ Flash memory
Note: The fl ash memory stores the data that is written by
the FPU (KPG-111D(C)), tuning data (Deviation, Squelch,
etc.) ,and fi rmware program (User mode, Test mode, Tuning
mode, etc.). This data must be rewritten when replacing the
fl ash memory.
■ SRAM (Static memory)
Note: The SRAM has temporary data area and work area.
When the power supply is off, it is backed up by an internal
secondary lithium battery. Therefore, the saved data is not
lost.
■ Real-time clock
The clock function is based on real-time clock IC (IC106).
When the power supply is off, it is backed up by an internal
secondary lithium battery.
6-3. LCD
The LCD is controlled using the bus lines on the connec-
tor (CN1) of the Control unit (X53-426). It corrects the LCD
contrast voltage using IC1.
6-4. Key Detection Circuit
Keys are detected using the key scan circuit in IC108.
The /KEYI signals that are normally pulled down go high
when any key is pressed.
6-5. Low Battery Warning
The battery voltage is divided using R444 and R445 and
is detected by the ASIC (IC108). When the battery voltage
falls below the voltage set by the Low battery warning ad-
justment, the red LED blinks to notify the operator that it is
time to replace the battery. If the battery voltage falls even
more (approx. 5.8V), a beep sounds and transmission stops.
Low battery warning
The red LED blinks during
transmission.
The red LED blinks and the
warning tone beeps while the
PTT switch is pressed.
38
CIRCUIT DESCRIPTION /
Battery condition
The battery voltage is low but
the transceiver is still usable.
The battery voltage is low and
the transceiver is not usable to
make calls.
电路说明
6-1. ASIC
A S I C ( I C108) 是一个 32 位 R I S C 处理器，具备外围功能和
ADC/DAC。
该 ASIC 以 18.432MHz 时钟和 3.3V/1.5V DC 运行。它控制
闪存，SRAM，DSP，接收电路，发射机电路，控制电路以及显
示电路，并与外部设备双向传输数据。
6-2. 存储电路
存储电路由 ASIC(IC108)，SRAM(IC103) 和闪存 (IC101) 组
成。闪存具有 32M 位的容量，包含 ASIC 的手持对讲机控制程
序并储存数据。它也保存手持对讲机信道的数据和由 F P U 写
入的操作参数。此程序很容易从外部设备写入。SRAM 具有 1M
位的容量，包含工作区和数据区。
■闪存
注意 : 闪存可储存由 FPU(KPG-111D(C)) 写入的数据，调谐数
据 ( 频偏，静噪等 ) 以及固件程序 ( 用户模式，测试模式，
调谐模式等 )。更换闪存后，此数据必须重写。
■ SRAM( 静态存储器 )
注意 :SRAM 含有临时数据区和工作区。当电源关闭时，则以内
部二次锂电池作为后备电源。因此，保存的数据不会丢失。
■实时时钟
时钟功能以实时时钟 I C ( I C106) 为基础。当电源关闭时，则
以内部二次锂电池作为后备电源。
6-3. LCD
L C D 通过控制单元 ( X53-426) 的通用连接器 ( C N1) 上的总
线线路进行控制。它使用 IC1 校正 LCD 电压差异。
6-4. 按键检测电路
按键用 I C108 中的按键扫描电路进行检测。按任意按键时，
通常降低的 /KEYI 信号会升高。
6-5. 低电池电量警告
电池电压用 R444 和 R445 进行分割，由 A S I C ( I C108) 进行
检测。当电池电压下降到由低电池电量警告调整设定的电压
以下时，红色 L E D 闪烁，通知操作者应当更换电池了。如果
电池电压进一步下降 ( 约 5.8V)，则会响起提示音，发射将停
止。
低电池电量警告
发射期间红色 LED 闪烁。
按下 PTT 开关时，红色 LED 闪
烁并响起警告音。
电池状态
电池电压低，但手持对讲机仍
能使用。
电池电压低，不能使用手持对
讲机进行呼叫。