Max7219 With Custom PCB for RC Vehicles

This is my first ever PCB made on my custom CNC. And i am very pleased to see the results. Just want to share the Dos and Don'ts

Its a custom PCB made to control LEDs of a truck using microcontroller. Which other wise would not be possible due to limitation of output pins

This PCB and the IC can help you control over 64 LEDs individually.

The snap above although looks very good it was a V3 of the PCB and currently m already on V4 that is a bit easier to solder and uses very less connections

Please be aware the below tutorial requires one to have at least beginner level skills in the following (I am not sure where i stand m a learner/beginner)

Operating a CNC

Electronics Knowledge

• A CNC or access to one
• Design software to Design circuits (I have used EASY EDA)
• A software to convert that design to G-code (I have used Flat-CAM)
• A software to send that G-Code to your CNC (I have used grbl Control)
• Soldering iron setup
• 10Kohm Resistor x 1
• 10 uf 20-50V capacitor x 1
• 0.1 uf capacitor x 1
• MAX7219
• 10x 2.54mm 8 pin male OR female headers

Heres the final schematic of my V4 of the PCB

This is pure n simple keeping in mind my soldering skills and limitation to a single sided PCB

P1 and P2 needed to be short i didnt find a way around to skip this one jumper apart from that m very happy theres no jumper or overlapping on my PCB having a 24 PIN IC with sequence all over the palce

So i have mentioned here for ease also

I would have shared an excel if instructables allowed no issue though

this PCB or sequence is good with arduino library "LedControl.h"

let me give small example here just so that theres no confusion left.

The following piece of code from my truck will light up Row 1, 4 LEDs placed in column 3456

if (RemoteXY.HL!=0){lc.setRow(0,0,B00111100);}else{lc.setRow(0,0,B00000000); }//headlight

How can i wire em up ??

Please note the numbers mentioned on the PCB snap above

Merge the cathode of all 4 LEDs on Rows pin numbered as 1 and anodes on column mentioned as 3 4 5 and 6.

For all my PCBs i have locked the CNC as following it gives me best result (The video is for V3 PCB)

For MY CNC

• Flute 0.3 tip angle 30
• Z- Axis for tracks = -0.1mm
• 350 Feed for all XYZ

Currently i drill just the guide holes and drill manually by small motor

For guide holes i use the same bit as above with Z-axis -0.7mm It gives me good enough ditch to accurately drill the PCB later on.

I can do the drilling on my CNC as well but its belt driven so the changes of moving it by mistake are a lot during bit change. So i dont take the risk

• Soldering a naked PCB like this one with so much bare copper is difficult. Believe me on this one. Use smaller tip and least amount of solder.
• Never ever directly mount an IC always use its socket if you are a beginner like me
• Always clean the solder tip as much as you can after every 2-3 joints

I have never uploaded any content of me soldering, i myself found my skills to be super cringy, don't want to ruin people's mood :D

Here are somethings i learnt during this PCB making

• DONOT hesitate to test n try things out. I never thought my CNC was accurate enough to mill a PCB and never though of even making this board it sounded so complex.
• Keep the tracks at max width possible and engrave deeper tracks when you are not clearing unwanted PCB area
• Put some water on PCB during milling it help reduce the noise and edges are much smoother (Dont know the science i thing it helps in cooling down and lubricate as well)
• Use good quality soldering iron and solder , the difference is night and day if you are beginner
• NEVER EVER go designing a circuit without reading the main CHIPS datasheet.

EXTRAs

NEVER EVER go designing a circuit without reading the main CHIPS datasheet.

Read hardware, devices manuals they tell a lot about the right way to operate and keep em healthy

This is a part of my RC truck i was making years ago and abended due to job. The electronics is almost done now. Just need to give some finishing touches and will be sharing that experience here as well.

The video of the previous progress can be found on my YT channel.

https://www.youtube.com/channel/UCokJfoBvnh7wryR4sl1qagg