Kenwood NX-220 Service Manual page 22

NX-220
3) Sending frequency program data to the PLL.
4) Controlling squelch on/off by the DC voltage from the
squelch circuit.
5) Controlling the audio mute circuit by decode data input.
6-1. ASIC
The ASIC (IC610) 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 (IC610), the
SRAM (IC605), and the flash memory (IC601). The flash
memory has a capacity of 32M-bit that contains the trans-
ceiver control program for the ASIC and stores the data. It
also stores the data for transceiver channels and operating
parameters that are written by the FPU. This program can
be easily written from external devices. The SRAM has a
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-141D(C)), tuning data (Deviation, Squelch,
etc.), and fi rmware program (User mode, Test mode, Tuning
mode, etc.).
■ SRAM (Static memory)
Note: The SRAM has a temporary data area and work area.
6-3. LCD
The LCD is controlled using the 4 serial lines (SDI0, /
LCDCS, SCK0, SDO0) from the ASIC (IC610).
6-4. Key detection circuit
Keys are detected using the LCD controller driver IC (IC8).
If a pressed key is detected by IC8, it is informed to IC610
through the serial line.
6-5. Low battery warning
The battery voltage is divided using R514 and R515 and
is detected by the ASIC (IC610). 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.
6-6. DSP
The DSP circuit consists of a DSP (IC603) and processes
the baseband signal. The DSP operates on an external clock
22
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
3) 将频率数据发送到 PLL。
4) 由静噪电路的 DC 电压控制静噪的开 / 关。
5) 由输入的解码数据控制音频静音电路。
6-1. ASIC
ASIC(IC610) 是 32 位 RISC 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。用以控
制闪存、SRAM、DSP、接收电路、发射电路、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(IC610)、SRAM(IC605) 和闪存 (IC601) 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。同时还保存手持对讲机信道的数据及 F P U 写
入的运行参数。可以轻松通过外部设备写入此程序。S R A M 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 FPU(KPG-141D(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 )。
■ SRAM( 静态存储器 )
注意 ： SRAM 设有临时数据区和工作区。
6-3. LCD
LCD 通过 ASIC(IC610) 的 4 条串行控制线 (SDI0、/LCDCS、
SCK0、SDO0) 进行控制。
6-4. 按键检测电路
使用 LCD 控制器驱动 IC(IC8) 检测按键。如果 IC8 检测到
已有按键按下，则会通过串行线路通知 IC610。
6-5. 低电池电量警告
电池电压用 R514 和 R515 进行分压，并由 A S I C ( I C610) 进
行检测。当电池电压下降到低电池电量警告调整设定的电压
以下时，红色 L E D 闪烁，通知操作者及时更换电池。如果电
池电压进一步下降 ( 约 5.8V)，则会响起提示音，并将停止发
射。
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。
6-6. DSP
DSP 电路由 DSP(IC603) 组成，用以处理基带信号。DSP 在
18.432M H z 的外部时钟上运行 ( 与 I C610 相同 )，I / O 部分以
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。