Need someone to look over this IC design (its my first one)

Thread Starter

Evan_g

Joined Apr 29, 2024
7
The circuit shown below is intended to power and control 5 small stepper motors and 3 end/limit switches. It takes power from a wall outlet like shown below and converts the ac current to dc power. This voltage then gets bucked down and sent to microcontroller which then is connected to motor drivers and limit switches. I'm less concerned about having proper voltage and current to each part as I've made sure to pay close attention to that, I'm more concerned about smaller design flaws that may have been overlooked like signal noise, lack of passive components, ext. I'm also wondering if in this particular case would it be fine if I left all the unconnected pins as is or would it really be needed to connect them to a ground, let me know. Also, I apologize if the circuit is difficult to understand as it's my first one, I'm just looking for tips and things to improve on.

Labels -
AC/DC_PC - AC to DC power supply - 12V 30A
BC - Buck convertor - LM2596SX
MC - Microcontroller - PIC18F27K40-I/SP
TB - Terminal block - 1984963
SW - End/limit switch - D2F-01FL3-D3
M - Stepper motor - Steppers
DRV - Motor Driver - DRV8829PWP

Thank you so much for your help it's really appreciated!
Screenshot 2024-04-29 003342.pngScreenshot 2024-04-29 003342.png
 

LesJones

Joined Jan 8, 2017
4,226
You seem to be driving both coils of each stepper motor with the same signal. The stepper will not move.
You will need two of those driver chips for each stepper motor.

Les.
 

Thread Starter

Evan_g

Joined Apr 29, 2024
7
It doesn't look as though you have the driver output pin connections as per the datasheet :-

View attachment 321138
Sorry I'm having trouble understanding in what way the datasheet wants the outputs connected. I assumed that as it was a bipolar motor you would just connect an OUT1 pin and OUT2 pin to opposite sides of the coil but that doesn't seem to be the case. Is it asking for me to connect both OUT1 pins on the same coil and both OUT2 pins on the other? Also, in the comment above someone stated that I will need 2 driver chips to run the motor, is that truly the case?

Thank you so much for the help it means a lot!
 

Thread Starter

Evan_g

Joined Apr 29, 2024
7
You seem to be driving both coils of each stepper motor with the same signal. The stepper will not move.
You will need two of those driver chips for each stepper motor.

Les.
Hey, Less thanks for the help! I was wondering why you said I needed 2 different motor drivers to drive a singular bipolar motor. From the research I've done it seems like this motor controller should work fine individually for each stepper motor (other than some wiring issues I made, currently trying to fix). I'd love to understand your reasoning behind your comment so I can further progress my circuit into a hopefully fully functional one!
 

LesJones

Joined Jan 8, 2017
4,226
The coils of the stepper motor must be driven in sequence, not just on and off. The driver IC that you are using is only one H bridge so it only really has one output. Even though it has two pins for each output they must be connected together as Alec points out in post #3. With only one H bridge you can't drive the coils independently.
Her is a link to a bsic explanation of how to drive a stepper motor.
EDIT the TB6600 Stepper driver chip may be more suitable for your application as it contains two H bridge drivers

Les.
 
Last edited:

Alec_t

Joined Sep 17, 2013
14,407
Sorry I'm having trouble understanding in what way the datasheet wants the outputs connected.
My understanding of the datasheet is that pins 5 and 10 should be shorted together on the pcb and connect to one terminal of one coil. Pins 7 and 8 should be shorted together on the pcb and connect to the other terminal of that same coil. The IC drives only one coil.
It is not unusual for an IC to have multiple pins commoned, e.g. to aid heat dissipation or handle high currents.
 

Thread Starter

Evan_g

Joined Apr 29, 2024
7
My understanding of the datasheet is that pins 5 and 10 should be shorted together on the pcb and connect to one terminal of one coil. Pins 7 and 8 should be shorted together on the pcb and connect to the other terminal of that same coil. The IC drives only one coil.
It is not unusual for an IC to have multiple pins commoned, e.g. to aid heat dissipation or handle high currents.
Ah, it that makes sense now thank you for that clarification. I went ahead and remade the schematic with a driver someone else recommended earlier. If you don't mind, could you take a minute to make sure the driver setup is correct? You've already helped a lot so no rush in doing so but if you ever find yourself with some free time it would be nice to get one last check of the full circuit to make sure I'm not missing any important things. FYI, I plan on making it on a simulator initially before purchasing the PCB do you have any sims that you would recommend?
 

Attachments

Thread Starter

Evan_g

Joined Apr 29, 2024
7
The coils of the stepper motor must be driven in sequence, not just on and off. The driver IC that you are using is only one H bridge so it only really has one output. Even though it has two pins for each output they must be connected together as Alec points out in post #3. With only one H bridge you can't drive the coils independently.
Her is a link to a bsic explanation of how to drive a stepper motor.
EDIT the TB6600 Stepper driver chip may be more suitable for your application as it contains two H bridge drivers

Les.
Thanks so much for the recommendation on the driver it saved me lots of time. I was wondering if you noticed anything else off or possibly worrying about my circuit. As you know I'm a beginner so any sort of feedback good or bad is helpful. I linked the updated schematic with your driver recommendation implemented if you'd like to check it out!
 

Attachments

Thread Starter

Evan_g

Joined Apr 29, 2024
7
My understanding of the datasheet is that pins 5 and 10 should be shorted together on the pcb and connect to one terminal of one coil. Pins 7 and 8 should be shorted together on the pcb and connect to the other terminal of that same coil. The IC drives only one coil.
It is not unusual for an IC to have multiple pins commoned, e.g. to aid heat dissipation or handle high currents.
EDIT: Just realized I forgot to connect CW/CCW pins from the driver to the microcontroller, oops.
 

Thread Starter

Evan_g

Joined Apr 29, 2024
7
The coils of the stepper motor must be driven in sequence, not just on and off. The driver IC that you are using is only one H bridge so it only really has one output. Even though it has two pins for each output they must be connected together as Alec points out in post #3. With only one H bridge you can't drive the coils independently.
Her is a link to a bsic explanation of how to drive a stepper motor.
EDIT the TB6600 Stepper driver chip may be more suitable for your application as it contains two H bridge drivers

Les.
EDIT: Just realized I forgot to connect CW/CCW pins from the driver to the microcontroller, oops.
 

Alec_t

Joined Sep 17, 2013
14,407
do you have any sims that you would recommend?
Many members here use LTspice, a free download from Analog Devices. There are plenty of online tutorials to help the steep learning curve. It accepts many third-party models and there is a user group at Groups.io, which hosts model libraries. A model of the driver IC will be needed but is unlikely to be part of the standard LTspice download.
 
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