Raspberry Pi PCB
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The Raspberry Pi PCB can also support several different methods for controlling stepper motors and the components and GPIO connections used in a populated PCB set out in the table below can be used to illustrate these methods:
| Component | GPIO pin(s) |
| Tactile button (1) | GPIO#07 and GND connections across the button |
| Tactile button (2) | GPIO#26 and GND connections across the button |
| Stepper motor control board (ULN2003) | GPIOs #08, #11, #09 and #10 connect to the ULN2003 module's IN1, IN2, IN3 and IN4 pins respectively plus 5V and GND provided on the PCB's dedicated 7 pin female connector |
The set of components tabulated above allows many different movement control to be programmed using, for example, the test configuration shown in the image below right. Example 'starter' code has been developed in Python with the details below summarising just some of the options that are possible - all the currently available example software and documentation is available here.
Stepper Motor control and rotation example methods:
| 1 |
'Wave drive' stepper motor operation: a 28BYJ-48 stepper motor, controlled by a ULN2003 module is operated in this demonstration using a basic 'coil energisation' sequence method known as 'Wave'. The four control pins and the 5V + GND pins from the ULN2003 are connected to the dedicated 6 pin female connector on the PCB and Python code developed to rotate the stepper motor through one full rotation in the forward direction using this 'coil energisation' sequencing methods. |
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| 2 | 'Half-step' stepper motor operation: this method also uses the 28BYJ-48 stepper motor, controlled by a ULN2003 module but is operated using the 'coil energisation' sequence method known as 'Half step'. Using the same four control pins and the 5V + GND pins from the ULN2003 connected to the dedicated 6 pin female connector on the PCB, Python code developed to rotate the stepper motor through one full rotation in the forward direction using this 'coil energisation' sequencing method. |
The diagram above illustrates each of the different coil energisation methods. |
| 3 | 'Full-step' stepper motor operation: this method uses the 28BYJ-48 stepper motor, controlled by a ULN2003 module as well, but is operated using the 'coil energisation' sequence method known as 'Full step'. Using the same four control pins and the 5V + GND pins from the ULN2003 connected to the dedicated 6 pin female connector on the PCB, Python code developed to rotate the stepper motor through one full rotation in the forward direction using this 'coil energisation' sequencing method. | |
| More specialised Python code is also being considered for a temperature gauge demonstration that shows the CPU temperature, and this demonstration could also be developed to be accessible from a Python/Flask web interface. | ||
The simple control examples profiled above can be used to develop more advanced projects and some examples are shown here.
Electric motor control:
The following links provide more details on various aspects of this evolving PCB project development:
Details for all the Maker/robotics PCB projects:
All the currently available maker project information: