PIC18F的符LCD噪声和MOSFET开关问题

当然你有一个传导或辐射的电磁干扰。没有全图是不可能帮助的。需要电路图、PCB图和设备装配图。



      以下为原文

    Sure you have a conducted or radiated EMI. It is impossible to help without whole picture. The circuit diagram, PCB drawing and device assembly photos are needed.

检查LCD上的打开/未结束输入。检查旁路盖，电源接地路由。



      以下为原文

    Check for open/unterminated inputs on the LCD. Check bypass caps, power supply ground routing.

嗨，谢谢你们俩…我在通用PCB上做了电路。PCB尚未设计。对PCB设计有任何建议。JAJI在4位模式下使用LCD 16×2，PIN 7至10没有连接PCB设计的任何建议。谢谢



      以下为原文

    Hi,

Thanks Both of you...

@Nikolay
I have made circuit on General Purpose PCB. PCB not Designed Yet.
Any Suggestions for PCB designing..
@Jack
I am using LCD 16 x 2 in 4-bit Mode and Pin 7 to 10 are unconnected
Any Suggestions for PCB designing..

Thanks

建议：不要留下任何输入，连接未使用的输入。问题：什么是旁路帽？问：LCD是否与MOSFET切换的电流共享地线/跟踪（如果是坏主意）？



      以下为原文

   
Suggestion: don't leave any inputs unconnected, ground the unused inputs.
Question: What bypass caps are in place and where?
Question: does the LCD share the ground wire/trace with the currents you are switching with the MOSFETs (bad idea if so)?

1）是的…我将改变未连接的LCD引脚到GND2）。接近MCU、电源和LCD。3）不同的桥式整流器和MOSFET开关接地的LCD接地。谢谢你的建议。TS9



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1)Yes... I will change unconnected LCD pins to GND

2)
.1uF.. Near to MCU,Power Supplies, and LCD.

3) No. LCD Ground from Different Bridge Rectifier and MOSFET Switching Ground from other Bridge Rectifier..

Thanks for Suggestions..


/TS9

MOSFET开关的负载类型是什么？归纳法？



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    What type of loads are the mosfets switching? inductive?

重复的



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    Repeated

重复的



      以下为原文

    Repeated

不。。液体化学品（或水）化学实验室的用途。



      以下为原文

    No.. LIQUID chemicals (or Water) Chemical laboratory purposes.

有什么更新吗？



      以下为原文

    Any Update?

LCD是否只在LCD和MPU上正常工作？D0—D3不需要连接，只有当LCD被选开时，LCD才从端口读取。这不会修复错误。



      以下为原文

    Does the lcd work normally with just the lcd and mpu only?
 
D0 - D3 does not need to be connected, it's only when the lcd is strobed that the lcd reads from the port.
 
That will not fix the bug.
 

对。。液晶显示器工作正常，使用MCU。我看到只有在转换MOSFET（S）时LCD上的垃圾数据…D0—D3不需要连接吗？哪些针？Gnd或者别的什么。我在4位模式下使用LCD 16×2。我只需要写数据，不想从LCD中读取任何东西。谢谢



      以下为原文

    Yes.. LCD works fine Normally with MCU. I have seen garbage data on LCD only when switching MOSFET(s)...

D0-D3 does not need to be connected? which pins? Gnd or something else. I am using LCD 16 x 2 in 4-bit Mode. I only have to write data, don't want to read any thing from LCD.

Thanks

LCD数据引脚D4-D7是您在4位模式中使用的引脚。D0-D3不在4位模式下使用。检查引脚到LCD上的电压或使用范围。在无线接收器上，我有类似的问题，WiFi电源线上固定了一个大帽。



      以下为原文

    LCD databus pins D4 - D7 are the pins you use in 4bit mode.
D0 - D3 not used in 4bit mode.
 
Check the voltage on the pins going to the lcd or use a scope.
 
I had a similar problem on a wireless receiver, a big cap on the wifi powerlines fixed that.

感谢WiFi电源线也有MOSFET开关？电源或LCD附近的大帽？



      以下为原文

    Thanks

Wifi Power Lines have also MOSFET switching?

Big Cap in power supply or near LCD.?

虽然D0:D3不在4位模式中使用，但是显示器必须将它们读为零，所以它们应该连接到GND。最好是在电源处处理开关瞬变，也许用缓冲器或栅极电阻器从过渡处取锐边。电感器或铁氧体磁珠往往比电容器在阻断RF中更有效。你可以使用廉价的AM无线电调谐站作为EMI探测器。电容器应具有低ESR和低电感。也可能需要接地平面和屏蔽。如果显示器远离PIC，它可能有助于扭转导线，也可以使用屏蔽电缆。USB电缆是4线屏蔽电缆的良好来源。使用一片D4:D7，另一块用于控制信号。屏蔽可以为GND和VDD提供电源，或者如果你不使用R/W引脚，你可以使用一个用于VDD的线。



      以下为原文

    Although D0:D3 are not used in 4 bit mode, the display must read them as zeroes, so they should be connected to GND. It is best to handle switching transients at the source, perhaps with snubbers or gate resistors to take the sharp edge off the transitions. Inductors or ferrite beads are often more effective than capacitors in blocking RF. You can use a cheap AM radio tuned off-station as an EMI detector. Capacitors should be low ESR and low inductance. Ground planes and shielding may also be required.
 
If the display is located away from the PIC it may help to twist the wires, and also use a shielded cable. USB cables are a good source of 4 wire shielded cable. Use one piece for D4:D7 and another for the control signals. The shield can supply the power for GND and VDD, or if youaren't using the R/W pin you can use one of the wires for VDD.

用万用表测试LCD线，读取高电压和低电压。D4-D7、RS和E上有什么？帽子在LCD和GND之间。可能是LCD的DATARATE太快，运行速度太慢测试它。使用R/W尝试忙测试。



      以下为原文

    Test the lcd lines with a multimeter to read the high and low voltages.
What do you get on D4 - D7, RS and E?
 
A cap. between + and gnd on the lcd. 100nf.
 
Maybe the datarate to the lcd is too fast, run it extra slow to test it.
Try a busy test using R/W.
 
 

PaulI肯定会听从你的建议。液晶显示器不接近MCU。液晶显示器相当远。10cm采用FRC电缆。我将连接未使用的有线电视到GND。我应该连接LCD附近的MCU和PWM信号与10厘米的电线切换？？？GOT2015。我以前用MCU检查过。MCU的复位引脚在切换PWM和干扰LCD时是不稳定的，但是程序的其余部分如电压升降程序，LED工作良好。占线测试？LCD的忙标志检查方法。TS9



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    @Paul
I will definitely follow your suggestions.
LCD is Not Near to MCU. LCD is quite far. 10Cm With FRC Cable.
I will connect unused wired to GND.

Should I connect LCD near to MCU and PWM Signals with 10 cm Wire for switching ??

@Gort2015.
As earlier I have checked with MCU..The Reset Pin of MCU is unstable while switching PWM and disturb LCD but Rest of the program like Voltage up-down program, LED work fine.

Busy Test? Means Checking Busy Flag of LCD.

/TS9

对。



      以下为原文

    Yes.

@ PaulAny进一步的建议。“哥特OK…然后我会更新…



      以下为原文

    @Paul
Any Further Suggestions.?


@Gort
OK... I will then update..