Project Logs

Collapse

• Wiring between the Raspberry Pi and the front panel PC board

  Andrew Mitz • 11/14/2020 at 21:18 • 0 comments

  The writing between the Raspberry Pi and the front panel PC board is slightly different among the Raspberry Pi 3B, Raspberry Pi 3B+ and Raspberry Pi 4. I use a Raspberry Pi 3B+. The 3B and 3B+ run cool, which provides many hours of service. The Pi 4 is much warmer. I would rather not run it without a small fan. Fans tend to fail over time, so the 3B or 3B+ seems like a better choice. I buy the 3B+ because it is a newer design, but the 3B works file.

  To make the wiring differences more clear, I have updated the schematic with notes on each Raspberry Pi. I
  
  

  To make a simple harness I like to use a 10-pin female header to plug into the front panel board. I use an 8-pin female header on the GPIO header of the Raspberry Pi.  I solder color-coded ribbon wires between the two using standard color codes. The pin mapping from the front panel board to the GPIO pins are 1:1 for these pin numbers: 2, 3, 5, 6, 7. The last two pins of the 10-pin header connect depending on the specific Raspberry Pi board. 
  
  For the Pi 3B, simply wire pins 9 and 10 to the two RUN pins. Note, on all the Raspberry Pis, you must install a male header on the RUN pins yourself. I find this a big annoyance.  

  For the Pi 3B+ or the Pi 4, connect pin 9 to the RUN pin. Connect pin 10 to GPIO 39, which is a ground. The RUN header is 2 pin on the Pi 3B+. On the Pi 4, the header has three contacts and is called RUN/GLOBAL_EN. It still has a RUN pin.
  
   This picture shows the wiring of the cable harness before assembly. The example is a Pi 3B+.

  The next picture shows the harness wiring attached to the front panel PC board.
  
  

• Autodesk and STL files added for 3D print case

  Andrew Mitz • 11/01/2020 at 20:00 • 0 comments

  An Autodesk Fusion 360 export file and three STL files have been uploaded. This is a custom case for the PlayVideo. It has a general purpose Raspberry Pi 3B mounting on the bottom and the top section has holes for the PlayVideo printed circuit board. Note, the Autodesk file is suitable for anyone who wants to build a Raspberry Pi project with space above the board for a circuit and connectors. The layout fits the Raspberry Pi 3B and 3B+. 
  

  Note one side is removeable. When in place, it holds down the circuit board. The top holds the side panel in place. The top is secured with a single #6 screw. 

• Be careful about mounting the pushbutton switches

  Andrew Mitz • 10/05/2020 at 21:18 • 0 comments

  Be careful when assembling the PlayVideo Interface printed circuit board. All parts except the RF board and the 10-pin header mount on the front of the board. The front has most of the part markings. The RF board and header mount from the rear. Perhaps more subtle is the mounting of the two pushbutton switches. The board has the markings: C  NO  NC  for each switch. The switch fits into the board two ways, but only one orientation will put the COMMON on the left and NORMALLY CLOSED on the right. If you get this backwards, the circuit will think the switch it is being pushed continuously. 

• New case (soon) and issues with RUN pin on Pi 3b+ and 4

  Andrew Mitz • 10/05/2020 at 21:09 • 0 comments

  My next step is to create a custom case for the Pi 3b and front panel board. If all goes well, I will have a 3D printed case to hold both (rather than two separate boxes). 

  One issue that has come up switching from the Raspberry Pi 3b to the 3b+ is the "RUN" header. On the Pi 3b, the second pin next to the RUN header is ground. The "Start" pushbutton of my interface uses these two pins.  On the Pi 3b+ the second pin next to the RUN pin IS NOT GROUND. It is the PEN pin and cannot be used with the Start pushbutton. Also, none of the pins on the POE connector have a ground pin. For the Raspberry Pi 3b+, connect the Start pushbutton between the RUN pin and one of the ground pins on the GPIO header. The most convenient pin is probably pin 39. The Raspberry Pi 4 has a slightly different pin configuration, but the instructions are the same. Connect the Start pushbutton between the RUN pin and a GPIO ground pin.
  

• Version 1.1 of pc board. Drill template.

  Andrew Mitz • 08/06/2020 at 22:39 • 0 comments

  The m-pad-2.1 Eagle library has the 2N7000 TO-95 transistor layout wrong. I had to fix that. One pushbutton switch was inserted backwards. I added silk screen markings to make the orientation clear. I ordered an updated set of PC  boards from OSH Park. Meanwhile, I created a drill template in Adobe Illustrator. Here is a jpg of the file.

  The following drawing shows the hole sizes. Note, this is not to scale.

• Printed circuit board for the interface

  Andrew Mitz • 08/05/2020 at 21:17 • 0 comments

  I decided to design a circuit board for the interface box. Version V1.0 is built, but not tested yet. I expect it to work. V1.1 is already designed. It fixes a few holes and some component spacing. Here are some photos. 

View all 6 project logs