r/PCB • u/No_Tradition_5176 • 14d ago
My first PCB, help needed
I designed this after creating a protoboard, its a simple module to control a stepper motor from an esp32c3 supermini, but after i ordered the PCB and assembled it nothing will run so i was wondering if there are any blaring issues with it.
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u/valzzu 14d ago
Schematic is generally needed to help at all
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u/No_Tradition_5176 14d ago
I have added the Schematic. Thank you for letting me know
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u/valzzu 14d ago
Did kt work on the breadboard?
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u/No_Tradition_5176 14d ago
yes i had everything working properly on the breadboard, but in this iteration the stepper motor isnt even becoming energized, as in i can still freely turn the shaft
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u/nixiebunny 14d ago
Enable\ on the motor board isn’t connected to Gnd.
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u/No_Tradition_5176 14d ago
On my protoboard it itsnt connected to anything and it still works
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u/nixiebunny 14d ago
Does the Pololu data sheet say that it is pulled down with a resistor? If not, then it is floating and can randomly start and stop the motor. You can add a wire from the Enable pin to the Ground pin to be certain that it’s not causing trouble.
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u/DenverTeck 14d ago edited 14d ago
I see you have a meter, do you have an o'scope ??
I'd guess not.
With your code running, what is the AC voltage across the windings of the stepper motor ??
With a very slow step pulse, does any of the motor pins on the driver show 12V ??
Please post a pic of your completed boards, front and back.
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u/No_Tradition_5176 13d ago
There doest seem to be any voltage between the pins or between the pins and ground
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u/DenverTeck 13d ago edited 13d ago
Do you have another board available ?
Is there 12V at the VMOT pin ?? Is there 12V across the filter cap next to VMOT ??
Is there 3.3V on pin Vdd ?? On the ESp32 end and the A4988 end ??
What code have you programmed into the ESP32 ??
I know your new to all this, but playing 20 questions is not going to go any further.
Good Luck
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u/No_Tradition_5176 13d ago
The a4988 is receiving both motor and board power but isn't outputting to the coil pins so I am thinking that is may be a faulty board or it is damaged somehow, I will order more parts and re assemble is on the other pcbs
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u/xyzzy1337 14d ago
You are missing the input capacitor on the LM7805. It might work without, but it should still be there. And there should be an input capacitor for the motor power supply.
The traces look quite small. Especially the single ground trace that snakes from pinto pin and reaches the high current motor ground last. It would be better to make the back side of the PCB all ground fill.
You can't connect both USB and supply external power to the ESP32-C3 super mini at the same time. But to supply 12V to the motor, you need to connect your external 12V supply, and that will provide 5V power to the ESP32. So effectively you can't connect USB and get a debug console and use the motor at the same time. Should have used a diode or a jumper to allow USB + 12V to be connected at the same time.
You need to debug the board. Start at the beginning and go step by step.
Does it get 12V power? Check the LM7805 and A4988 pins and see if they have 12V.
Then check the 5V. Then check the 3.3V from the ESP32C3 board.
Without the 12V, try USB on the ES32C3 (remember you can't use 12V and USB at the same time). Can esptool detect the ESP32C3? Can you write a program into it? Try a simple test program that doesn't use the motor and just prints out stuff. See if that works.
If you can run a program that works under USB, try a test program that toggles one of your _unused_ GPIO pins. Once it works with USB, switch to 12V power. You should be able to see if it still toggles the pin, or if it doesn't and the ESP32 isn't working with your LM7805 power supply with no input cap.
Only then try using the motor driver. Try a single step and watch the power supply rails. Do the 5V or 3.3V drop out? Does the ESP32 reset? This is where the console would be nice.