Repost: Martin's PPM tester

[Al Clark]

Martin,

Your 3D printed case is very nice! Would you be willing to share the STL file? I'd like to make one of these testers in a small case as you have done.

Al

[Martin]

No problem Al. Please find attached a zip containing both the .stl files, and the OpenScad design files in case you want to tweak the sizes a little and re-
export the .stl files using OpenScad (which is an excellent, and free, 3D CAD program).

But remember, this case was for the ATtiny85 version, with the 0.96-inch OLED. You'll definitely need to change the dimensions if you're using a Nano, or Pro Mini, or the larger 1.3-inch display. The dimensions are pretty easy to change though - mostly they're up at the top of the OpenScad files:

Code: Select all

width = 29.8; // internal width to suit board
height = 40; // height to suit board
depth = 18; // internal depth of bezel
wallThk = 1.5;
windowWidth = 23.5;
windowHeight = 13;
windowTop = 6;

It's been ages since I printed mine, and I only ever printed the one. I think it worked okay without needing any fettling, but there are no doubt improvements that could be made if you intend to print several.

[Al Clark]

Martin,

Sorry about the delay in getting back to you! I've been tied up on some priority projects. Thanks very much for the STL files! As soon as I get time I'll have a go at making one with the small components. So nice of you to make all this information available.

Al

[Al Clark]

Martin,

What size LiPo are you using?

Al

[Martin]

It was one of those small square LiPos. Just a single cell, but I fitted one of those little 'powerbank' boards, that have protection circuits for the cell, allow it to be charged via a micro-USB connector, and provide a stepped-up 5V output. I think the capacity was about 70 to 150mAh. I superglued the back on my tester, so I can't easily get inside to check now.

You can see the powerbank board in the video - about 34 seconds in, when I flicked off the back (before it was superglued). The battery is hiding underneath the powerbank board.

[Al Clark]

OK, thanks for that info.

Al

[Al Clark]

Martin,

You used an ATtiny85 in your PPM tester, and I have a Digispark board I want to use but not sure about the pinouts (I am also using the little LiPo battery and charger/controller board that you used). Can you please share which wires go where on the Digispark? I don't seem to be able to equate the ProMini holes, shown earlier in this thread, to my Digispark holes. The available holes on my Digispark are VIN; GND; 5V and P0(AREF,SDA,OI,PWM); P1(DO,PWM); P2(D/A and SCK); P3(D/A and USB+); P4(PWM, D/A,USB-); and P5 (D/A).

Al

[Martin]

My ATtiny85 version of the PPM tester currently only supports the OLED displays with the SSD1306 driver chip. These tend to be the 0.96-inch OLEDs. The larger 1.3-inch OLEDs usually have the SH1106 driver chip instead.

Connect the OLED SDA pin to SDA(P0) and the OLED SCL pin to SCK(P2). The PPM signal connects to P1.

See comments at the top of the PPMtesterATtiny85OLED.ino file for recommendations about pull-up and inline resistors, and maybe a capacitor!

I added the ATtiny85 zip file as an attachment to the opening post, in case you don't already have it.

[Al Clark]

Thanks Martin!

Al

[Al Clark]

Martin,

Sorry to pester you, but I've run into a small issue. When I try to compile the ATtiny85 sketch for the Digispark (Default-16.5 MHz) I get the following error message:

Arduino: 1.8.15 (Windows 10), Board: "Digispark (Default - 16.5mhz)"
Sketch uses 7136 bytes (118%) of program storage space. Maximum is 6012 bytes.
Global variables use 206 bytes of dynamic memory.text section exceeds available space in board
Sketch too big; see https://support.arduino.cc/hc/en-us/art ... 0013825179 for tips on reducing it.
Error compiling for board Digispark (Default - 16.5mhz).
This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

I assume you used a stand-alone ATtiny85 chip. Perhaps the chip used on the Digispark has a smaller memory. Any ideas?