How to become an elegant Hardware Engineer?

grace ？ Hardware ？ The two seemingly unrelated words had a wonderful chemical reaction in the hands of our engineers , Make it closely combined . Recently found a treasure up He has published new works —— The second ammeter of young people . Project acquisition method ： Log in to the official website of hard start x.jlc.com, Search for “ Analog and five digit source table / ammeter （ One ） control section ” that will do .

The authors of this project are divided into 2 Items uploaded （ because 2 Block plate ）, This article mainly explains the first part （ control section ）, The author is free for you to download and reprint , Remember to praise the author when downloading 、 Comment on 、 Share .

Project name ： Analog and five digit source table  /  ammeter （ One ）

Copyright fee ：0 element ;

Provide information ： The whole project + Source code ;

author ： amagsty;

# Analog bar   # ammeter

（ Front view of control part ）

This is a multi-purpose indicator , It can be used as USB Source table , Or ordinary ammeter . Large range , Fast switching speed , And with LED Analog indicator .

Product Brief ：

• The current display is from 1uA - 1mA - 200mA - 1A - 5A Source meter for automatic range switching of four gears ;

• Fast range switching , Can be used for low power consumption 、 Current monitoring during state switching such as sleep wake ;

• Active amplification , Low internal resistance , Maximum partial voltage of current detection resistance in all ranges <=20mV（ Not included mos Pipe internal resistance ）;

• Bridging USB2.0, It can be directly connected to the computer and the development board , Real time detection of development board current .

Application scenarios ：

• Electronic product development ;

• Low power test ;

• Maintenance of low voltage electrical appliances .

Product overview ：

• An operational amplifier is used inside the ammeter to amplify the sampling voltage to reduce the internal resistance ,原理图中设置了4 Range , Other range assignments can be achieved by changing the sampling resistance .

• Range switching use STM8 control , After exceeding the sampling voltage of this gear , The rising edge of the output of the comparator is STM8 The interrupt , To switch to a higher range .

• On both sides TYPEC, On the left is input , On the right is the output . Two of the mother seat CC Line 、D+ D- The data cable is directly connected , It can be used for protocol boosting or bridging USB2.0 equipment .

• The circuit of this machine is powered by battery （ Common land ）, The power input ripple does not affect the accuracy .

• Through to TYPEC Male HACK It can be used in conventional ammeters .

• This project is a prototype , It is known that there are still some deficiencies , Please be sure to read the attached ： Special notes _ Please be sure to read in advance .pdf.

Product parameters ：

• The power supply provides ：Type-C

• Range and internal resistance （ A typical ）：

• 0-1mA：20.05R（mos internal resistance 50mR）;

• 1-200mA：0.15R（mos internal resistance 50mR）;

• 200mA-1A：0.07R（mos internal resistance 50mR）;

• 1-5A：0.014R（mos internal resistance 10mR）;

• Long term maximum current ：5A;

• After power off, in VCC GND Reverse voltage of ： Less than 20V;

• accuracy ： After calibration, the full range can reach 0.5%, But the long-term stability has not been tested ;

• Battery capacity ：500mAh Offer about 5 Hours of use , The charging mode is charging after shutdown , After power on, the charging chip will be disconnected .

Instructions ：

Connect the flat cable to use 12P ffc , Please refer to the attached ： Buy links .zip

（ Schematic diagram of module connection mode ）

The project is divided into ：PCB、3D Printed case 、 Acrylic panel 、 The battery 、 The screen 、 Assembly parts .

PCB Direct proofing （2 slice ）;

3D The source files of printing and acrylic panel can be placed in Lichuang mall .

remarks ：

1、 This project consists of two parts , Need to cooperate ：《 Analog and five digit source table / ammeter （ One ） control section 》, Please click my homepage to view .

2、 Because some components need to be purchased outside Lichuang mall ,BOM Components to be purchased additionally in the list 、 Direct plug-ins are set not to SMT Mounting , Please mount this part of the device manually .

3、 In addition, if a small amount PCBA, Because there are many kinds of devices , The cost of refueling is high , You can also choose to proofing only PCB, All are installed manually .

• In the schematic diagram, due to the use of packaging , The model of operational amplifier is inconsistent with the actual , It should be ：MAX4239AUT+T（ Silk screen ABAA）, Please pay attention to the corresponding instructions in the schematic diagram .

• Before implementing this project , Please be sure to read the attached ： Production instructions _ Please read first .pdf.

• This project requires burning procedures , For the specific source code, please refer to the attached ：STVD Source code .zip.

• The source code needs STVD open , When burning, you need to provide 3-5V Power Supply , And with STLINK Common land .

4. Cost components ：

• plate 1 about ：￥70

• plate 2 about ：￥45

• 3D Print case ：￥11

• Transparent acrylic finished product Acrylic 2.8 200*300 x1p

• Transparent acrylic finished product Acrylic 2.0 200*300 x1p

• Because the panel size is small , There will be several sets of finished products , Not included in the cost for the time being

• The battery ：￥10

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The total cost of the whole set is about ：￥150 element （ Not calculated PCB、SMT）

The screen 、 Please refer to the battery in the attachment ： Buy links .zip

5. Recommendation board 2 Of LED Use SMT Mounting , The rest are installed manually .

6. Because of space ,PCB Component tag number silk screen is not placed on , Please refer to the in the attachment ：

Paste dot bitmap .zip

It can be printed out for easy installation , You can also directly import ：

Lichuang EDA Professional local file .zip, Use Lichuang EDA Of “ Welding assistant ” Finish mounting .

7. Attachment list ：

Special notes _ Please be sure to read in advance .zip

3D Print （STL Format ）.zip

Panel printing .zip

STVD Source code .zip

Buy links .zip

Structural dimension drawings .zip

Paste dot bitmap .zip

Lichuang EDA Professional local file .zip

Test video ：

Accuracy test in the video （ Calibrated ）, And from Wei an -5A Test of gear shift .

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