PCB check

2 DC motors drive using l293d and atmega 328p
can anybody check it plz

Thats not a 328!!

Hi,
If you want us to check your PCB, you need to supply the schematic for it as well.
Certainly the wrong footprint for a 328p.

Tom.... :slight_smile:

The track that you have put on the underside of the PCB, you could have routed between the two rows of pins of the ATmega328P, thus making the PCB single sided instead of double sided.

As already mentioned you have the wrong footprint for the microcontroller, you have chosen a 28 pin DIL package with a 0.6" spacing between the two rows of pins, you require 0.3" spacing. (The same as the other IC).

Some of the tracks are extremely thin, and could become open circuit if over-etched.

One thin track that I am particularly concerned about is the one going to pin 8 of the microcontroller, it’s the GND connection! You have got thicker tracks going to the crystal.

JohnLincoln:
The track that you have put on the underside of the PCB, you could have routed between the two rows of pins of the ATmega328P, thus making the PCB single sided instead of double sided.

As already mentioned you have the wrong footprint for the microcontroller, you have chosen a 28 pin DIL package with a 0.6" spacing between the two rows of pins, you require 0.3" spacing. (The same as the other IC).

Some of the tracks are extremely thin, and could become open circuit if over-etched.

One thin track that I am particularly concerned about is the one going to pin 8 of the microcontroller, it's the GND connection! You have got thicker tracks going to the crystal.

thanks a lot....I appreciate the tip about passing the track to pin 20 between the two rows of pins!

Hi,
Any of your tracks that are going to carry power and gnd should be much bigger,particularly where motor current and the drive chips are concerned
.
You have the room and there is no sin in leaving as much copper on the PCB as possible, so all power tracks need to be beefed up.

You don't say how much power the motors consume.
Please a schematic in jpg, its the only real way we can check your PCB.

Tom.... :slight_smile:

maged_alex:
thanks a lot....I appreciate the tip about passing the track to pin 20 between the two rows of pins!

The ground pins of your motor controller chip are also used as a heat sink, so the copper area around them should be as large as possible. One big pad for all four pins.

TomGeorge:
Hi,
Any of your tracks that are going to carry power and gnd should be much bigger,particularly where motor current and the drive chips are concerned
.
You have the room and there is no sin in leaving as much copper on the PCB as possible, so all power tracks need to be beefed up.

You don't say how much power the motors consume.
Please a schematic in jpg, its the only real way we can check your PCB.

Tom.... :slight_smile:

thanks

Henry_Best:
The ground pins of your motor controller chip are also used as a heat sink, so the copper area around them should be as large as possible. One big pad for all four pins.

thanks

maged_alex:
thanks

Still not enough copper around those 4 pins. You need one big, as big as possible, pad for all four pins.
And you should also make your tracks without square corners. Either curve them or make diagonal 'corners'.

We have requested that you post a schematic. This will determine if you have everything connected properly. Right now, we don’t know what pins you are using for any component. You ARE making this PCB from a schematic, right? If you are not, this PCB will fail.

Have you ever looked at pics of PCBs? You really need to Google “arduino pcb” and look how they are routed. You have so much wasted space. How are you going to program the 328? Where is reset? You need a couple of caps near VCC on the 328.

Add ground fill to both sides. Add ICSP header for bootloader installation and FTDI header for connecting FTDI Basic for sketch download and debugging via serial monitor.
Lot of unused IO pins. Add a header hole next to them so you can use if needed.
Add some extra power & Gnd pins to hook stuff up if needed.

Add a header hole next to them so you can use if needed.

That's experience talking.

Its nice to have at least one LED attached to a pin if you have the board space.

codlink:
We have requested that you post a schematic. This will determine if you have everything connected properly. Right now, we don't know what pins you are using for any component. You ARE making this PCB from a schematic, right? If you are not, this PCB will fail.

Have you ever looked at pics of PCBs? You really need to Google "arduino pcb" and look how they are routed. You have so much wasted space. How are you going to program the 328? Where is reset? You need a couple of caps near VCC on the 328.

I do the schematic on a piece of paper...I use the Arduino uno as a programmer and the PCB is working fine!

CrossRoads:
Add ground fill to both sides. Add ICSP header for bootloader installation and FTDI header for connecting FTDI Basic for sketch download and debugging via serial monitor.
Lot of unused IO pins. Add a header hole next to them so you can use if needed.
Add some extra power & Gnd pins to hook stuff up if needed.

Thanks a lot sir...I wait for your reply...and you always teach me a lot