Kenwood NX-820 Service Manual page 24

NX-820
6. Control Circuit
The control circuit consists of the ASIC (IC507) and its
peripheral circuits. IC507 mainly performs the following:
1) Switching between transmission and reception via the
PTT signal input.
2) Reading system, zone, frequency, and program data from
the memory circuit.
3) Sending frequency program data to the PLL.
4) Controlling the squelch on/off using the DC voltage from
the squelch circuit.
5) Controlling the audio mute circuit using the decode data
input.
6-1. ASIC
The ASIC (IC507) is a 32bit RISC processor, equipped
with a 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 (IC507), the
SRAM (IC503) and the flash memory (IC501). The flash
memory has a capacity of 32Mbit which contains the trans-
ceiver control program for the ASIC and stores the data. It
also stores the data for the transceiver channels and operat-
ing parameters that are written by the FPU. This program
can be easily written from external devices. The SRAM has
a capacity of 1Mbit which contains the work area and data
area.
■ Flash memory
Note: The flash 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. Display Unit
The display unit is composed of the LCD driver IC (IC1),
the LCD & Key backlight, etc.
The LCD is controlled using the 4 serial lines (LCDDI,
LCDCE, LCDCL, LCDDO) from the ASIC (IC507).
6-4. Key Detection Circuit
The keys are detected using an LCD driver IC (IC1). If a
pressed key is detected by IC1, the information is passed to
IC507 through the serial line.
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CIRCUIT DESCRIPTION / 电路说明
6. 控制电路
控制电路由 ASIC (IC507) 和外围电路组成。IC507 主要执
行以下功能 ：
1) 由输入的 PTT 信号切换发射和接收。
2) 从存储电路读取系统、区域、频率和编程数据。
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
AS IC ( IC507) 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 (IC507)、 SRAM (IC503) 和闪存 (IC501)
组成。闪存具有 32M 位的容量，包含 ASIC 的车载对讲机控制
程序并储存数据。同时还保存车载对讲机信道的数据及 FPU
写入的运行参数。可以轻松通过外部设备写入此程序。S RA 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. 显示单元
显示单元由 LCD 驱动 IC (IC1)、以及 LCD 和按键背光等部
分组成。
LC D 通 过 ASI C (I C507) 的 4 条 串 行 控 制 线 ( LC DD I、
LCDCE、LCDCL、LCDDO) 进行控制。
6-4. 按键检测电路
使用 LCD 驱动 IC (IC1) 检测按键。如果 IC1 检测到已有
按键按下，则会通过串行线路通知 IC507。