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参数资料
| 型号： | M37545G4-XXXGP |
| 元件分类： | 微控制器/微处理器 |
| 英文描述： | 8-BIT, MROM, 4 MHz, MICROCONTROLLER, PQFP32 |
| 封装： | 7 X 7 MM, 0.80 MM PITCH, PLASTIC, LQFP-32 |
| 文件页数： | 46/65页 |
| 文件大小： | 782K |
| 代理商： | M37545G4-XXXGP |
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Rev.1.07
Mar 19, 2009
Page 48 of 60
REJ03B0140-0107
7545 Group
4. Setup for I/O ports
Setup I/O ports using hardware and software as follows:
<Hardware>
Connect a resistor of 100
or more to an I/O port in series.
<Software>
As for an input port, read data several times by a program for
checking whether input levels are equal or not.
As for an output port, since the output data may reverse
because of noise, rewrite data to its port latch at fixed periods.
Rewrite data to direction registers and pull-up control registers
at fixed periods.
Fig. 56 Setup for I/O ports
5. Providing of watchdog timer function by software
If a microcomputer runs away because of noise or others, it can
be detected by a software watchdog timer and the microcomputer
can be reset to normal operation. This is equal to or more
effective than program runaway detection by a hardware
watchdog timer.
The following shows an example of a watchdog timer provided
by software.
In the following example, to reset a microcomputer to normal
operation, the main routine detects errors of the interrupt
processing routine and the interrupt processing routine detects
errors of the main routine.
This example assumes that interrupt processing is repeated
multiple times in a single main routine processing.
<The main routine>
Assigns a single byte of RAM to a software watchdog timer
(SWDT) and writes the initial value N in the SWDT once at
each execution of the main routine. The initial value N should
satisfy the following condition:
N+1
≥ (Counts of interrupt processing executed in each main
routine)
As the main routine execution cycle may change because of an
interrupt processing or others, the initial value N should have a
margin.
Watches the operation of the interrupt processing routine by
comparing the SWDT contents with counts of interrupt
processing after the initial value N has been set.
Detects that the interrupt processing routine has failed and
determines to branch to the program initialization routine for
recovery processing in the following case:
If the SWDT contents do not change after interrupt processing.
<The interrupt processing routine>
Decrements the SWDT contents by 1 at each interrupt
processing.
Determines that the main routine operates normally when the
SWDT contents are reset to the initial value N at almost fixed
cycles (at the fixed interrupt processing count).
Detects that the main routine has failed and determines to
branch to the program initialization routine for recovery
processing in the following case:
If the SWDT contents are not initialized to the initial value N
but continued to decrement and if they reach 0 or less.
Fig. 57 Watchdog timer by software
Direction register
Port latch
Data bus
I/O port pins
Noise
N.G.
O.K.
Main routine
(SWDT)
← N
CLI
Main processing
(SWDT)
Interrupt processing
routine errors
N
Interrupt processing routine
(SWDT)
← (SWDT)1
Interrupt processing
(SWDT)
Main routine
errors
>0
≤0
RTI
Return
=N?
≤0?
≠N
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相关代理商/技术参数 |
参数描述 |
|---|---|
| M37545G6GP | 制造商:RENESAS 制造商全称:Renesas Technology Corp 功能描述:SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER |
| M37545G6GP#U0 | 功能描述:MCU 3/5V 24K 32-LQFP QZ-ROM RoHS:是 类别:集成电路 (IC) >> 嵌入式 - 微控制器， 系列:740/38000 标准包装:250 系列:80C 核心处理器:8051 芯体尺寸:8-位 速度:16MHz 连通性:EBI/EMI，I²C，UART/USART 外围设备:POR，PWM，WDT 输入/输出数:40 程序存储器容量:- 程序存储器类型:ROMless EEPROM 大小:- RAM 容量:256 x 8 电压 - 电源 (Vcc/Vdd):4.5 V ~ 5.5 V 数据转换器:A/D 8x10b 振荡器型:内部 工作温度:-40°C ~ 85°C 封装/外壳:68-LCC（J 形引线） 包装:带卷 (TR) |
| M37545G6KP | 制造商:RENESAS 制造商全称:Renesas Technology Corp 功能描述:SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER |
| M37545G6-XXXGP | 制造商:RENESAS 制造商全称:Renesas Technology Corp 功能描述:SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER |
| M37545G8GP | 制造商:RENESAS 制造商全称:Renesas Technology Corp 功能描述:SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER |
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