Junk electronics, new electronics

The controller board was meant to stay the same of course. But that gave me more headache than everything else…

As the firmware would have to be re-configured anyway I went for Repetier. And that meant moving it from Arduino IDE 1.0.5 to 1.8.1, which suddenly didn’t connect to the Bootloader of the Sanguinololu anymore. Google helped me by pointing me to http://dustsreprap.blogspot.de/2015/06/better-way-to-install-sanguino-in.html, which contained hints on how to fixed the connection problems.

Sadly no one ever documents what boot loader they used if any. The boot loader expects a certain baud rate and protocol. You need to try a few options. Find and edit you boards.txt fie that defines the sanguino. In there you find upload.protocol and upload.speed. for protocol the most common are arduino and stk500, upload speeds I have seen are 38400 and 57600. So try all of those combinations. These days I just us a avrisp and upload a known new bootloader so there is no guessing.

On windows 7 Youll find the boards.txt file that defines the sanguino in (you need to turn on hidden folders) users>you>appdata>roaming>arduino15>packages>Sanguino>hardware>avr>1.0.0>boards.txt. The stk500_getsync() error was fixed after editing the upload.speed from 152000 to 57600 for the chip i was using (1284p16mhz).

But at some point the whole board started to behave strangely. After borrowing and AVR ISP and flashing a second ATMEGA 1284P controller did not help, and burning my finger at the LM7805, I connected the whole controller board to a lab power supply. Had to discover, that it sunk more than 300 mA idle current somewhere. That could be suppressed by removing one of the stepper divers, but interchanging them revealed that not one of the Black Edition A4988 Stepper Motor Drivers was the cause, but the carrier board itself.

As I could not fix the PCB I had to mark it as worn out. But a while before that the RAMPS / Arduino Mega of the Sumpod also had trouble with driving the steppers. Apparently some thermally conductive “adhesive” had crept into the socket strips.

As we had a spare ´mega the Sumpod got a new RAMPS from eBay and a fresh set of drivers (the DRV8825 version this time) and I could thoroughly test a freshly arrived DR560-A Desoldering Iron from JBC. 😉

The wire jumpers for the Sumpod RAMPS are explained here (and again I disconnected the 2560’s USB 5V rail, but this time via the “T2” MOSFET next to the polyfuse).

The old RAMPs now definitely will not have anything creep between pin and socket again… And meanwhile I read, that Repetier was not Open Source anymore – so I went back to Marlin. 😛

While we’re on it: the no-name PSU of the Sumpod also failed and was replaced by a branded, actively cooled one.


Another nuisance with the controller boards was their connection to the PC. A fluorescent lamp on my work bench could kill the USB connection, when switched off durint the wrong part of the mains’ 50 Hz sine wave. After that had ruined a 9h-print I finally hacked a cheap “CP09004” micro SD slot into place.

While the controller from the Sumpod could be salvaged for the JunkStrap I was still short of another LCD with click wheel. And while RoStrap could be moved around our residence (printing in the bedroom by day and in the kitchen in the evenings) the Junkstrap would be too heavy for that. And possibly even warp. It had to go to the cellar – and stay there.

Time to add a Raspberry Pi 3 Model B and a Noir Camera V2 to the wish list for my birthday.

And the Junkstrap was already capable of printing the M12 Camera Case by jbeale, so it didn’t have to lie around naked. I left the Raspberry Pi 3, 2 or B+ Case by Normand to the Sumpod, as those cases tend to warp and BuildTak neatly prevented it.

Setting up OctoPrint (as OctoPi, obviously) was extremely smooth – thanks, Gina, Guy and all the others! ❤

Problems came, when I moved everything to the cellar, where only one certain RasPi position could get me connected to our WiFi.

This was not the position to monitor the print from your sofa – so I had to mod a pigtail cable to the antenna, like described here.

That way I could keep my initial mounting position for ´pi and camera.

The mounting piece for the camera enclosure is here, the one for the RasPi here on Tinkercad.

After having a stable WiFi connection everything worked fine. And as the configuration is on a Windows-readable part of the µSD card, you don’t have to use SSH to access the RasPi at all… …until you wand to update the firmware of your Arduino.

Once I had modded the X-carriage I needed to reconfigure the Z-heigt. So I finally had the “severe inconveniece” to install PuTTY and do as the OctoPrint Firmware Updater demanded, to install AVRDUDE…

sudo apt-get update
sudo apt-get install avrdude

…before returning to web-interface only mode. And continue printing.


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