Summary of Turntable Photography Equipment using PIC16F84A
The article describes "Turn Photo," a device for creating 360-degree product animations by capturing images at precise intervals. A PC application controls a microcontroller to manage camera functions and rotate the product on a turntable using a stepper motor and gear system, ensuring stability and minimal vibration.
Parts used in Turn Photo:
- PIC16F628A microcontroller
- USB-to-Serial PL2303 converter IC
- ULN2803A IC transistor array
- Two opto-couplers
- Stepper motor (specifically M35ST-7P from an old HP scanner)
- Gears with a 1:25 ratio
- Circular plexiglass sheet (rotating plate)
- Delphi 7 PC application software
- 12V independent power source for the motor
- PL2303 PCB Module for electronics power
A friend asked me if I could build him a device that would allow him to take photos of his products in 360 degrees. That kind of photo is actually an animation that consists of several photos of the same product but from different angles. It means that we need a device that can be controllable and that could take pictures on even intervals.
UPDATE: English version of software is now available for download here.
The idea:
As we can see from the picture above, a device called “Turn Photo” controls the digital camera (focus and shutter) and the device itself is controlled by a PC application written in Delphi 7.
All project files are available for download by clicking on the red download button below.
Turn Photo – hardware
Roughly, the device consists of PIC16F628A microcontroller, USB<->Serial PL2303 converter IC, ULN2803A IC transistor array, 2 opto-couplers and one stepper motor. Electronics are powered from USB port, actually from a PL2303 PCB Module, and motor is powered by independent 12V power source.
Two versions of this device were built. The first one was with stepper motor from an old 5.25″ floppy drive TEAC 14769070-90. That is a unipolar motor with 4 coils inside, and it has a resolution of 1.8 degrees per step which makes 200 steps in total per one complete revolution. When we drive it with half-stepping method, it doubles to 400 steps per revolution. A problem with this realization was that I didn’t use gears between the motor and the rotating plate (a circular plexiglass sheet that holds/rotates the product) – it was a direct-drive. A thing to note here is that we need to rotate objects with the smallest speed possible to avoid them dancing all over the plate. So, with a direct-drive and slow motor speed it produced massive vibrations. When motor speeds up – vibrations disappear, but we don’t want it speeding around. After testing and trying to fix the problem by changing stepper motor driver parameters and using dampers I decided to abandon this direct-drive design.
Second version of mechanics (the winning combination) is done by using a stepper motor M35ST-7P from an old HP scanner which was also unipolar with 4 coils but with a much smaller resolution of just 7.5 degrees per step. It means that the motor makes just 48 steps per one revolution. The good thing is that two gears came with this motor and the steps were prescaled by 25 (1:25 gear ratio) which means we now have 360/48/25 = 0.3 degrees per step. Another good thing here is that we can drive it faster because the speed also reduces by 25 x. This solves the vibrations problem totally and now we also have a maximum of 1200 steps or even 2400 with half-stepping per one revolution of final “drive” gear.
For more detail: Turntable Photography Equipment using PIC16F84A
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What is the purpose of the Turn Photo device?
The device allows users to take photos of products in 360 degrees to create an animation consisting of several photos from different angles. -
How does the device control the camera and rotation?
A PC application written in Delphi 7 controls the digital camera focus and shutter while managing the device's rotation via a microcontroller. -
Why was the first version of the device abandoned?
The first version used a direct-drive design without gears which caused massive vibrations at slow speeds and required high speeds to stop shaking. -
What specific stepper motor was used in the final version?
The winning combination uses a unipolar stepper motor M35ST-7P taken from an old HP scanner. -
How does the gear ratio improve performance?
The 1:25 gear ratio prescales the steps, reducing resolution to 0.3 degrees per step and allowing faster drive speeds without vibration. -
Where does the device get its power?
The electronics are powered from the USB port via the PL2303 PCB Module, while the motor requires an independent 12V power source. -
Can the software be downloaded?
Yes, an English version of the software is available for download according to the update in the article.
