How to upload new firmware to the PolargraphSD v3.0

This is for a PolargraphSD v3.0, that’s based on the ESP32 microcontroller.

I’ve switched to using PlatformIO with VSCode as a development environment for PolargraphSD. Although the Arduino IDE is ubiquitous, PlatformIO allows me to use a best-of-breed IDE like VSCode or Atom. I use VSCode because I had a couple of problems with Atom.

PlatformIO is an extension that interfaces with microcontrollers, and manages libraries automatically in a more mature way than Arduino IDE.

There’s a guide to compiling the code using PlatformIO and Arduino IDE in the project wiki:

Uploading precompiled binary files

I will periodically include a compiled binary in the project, which you can use if you don’t want to go to the trouble of dealing with IDEs and source code and compiling it yourself.

The project binaries folder ( contains four files which should be loaded into four memory addresses on the ESP32.

| Address    | File                     |
| 0x1000     | bootloader_dio_40m.bin   |
| 0x8000     | partitions.bin           |
| 0xe000     | boot_app0.bin            |
| 0x10000    | firmware.bin             |

You can upload these files to the ESP32 that’s inside a PolargraphSD machine using a few methods.

ESP32 Flash Download Tool for Windows

The easiest for people on Windows is to use the ESP32 Flash Download tool that looks like:


You might also use esptool, which is a lovely python tool that does the same thing. It’s what most toolchains use because it’s command-line driven, and cross-platform. You’d use it with a command like this: --chip esp32 --port "COM9" --baud 921600 
  --before default_reset --after hard_reset write_flash -z 
  --flash_mode dio --flash_freq 40m --flash_size detect 
  0x1000 bootloader_dio_40m.bin 0x8000 partitions.bin 
  0xe000 boot_app0.bin 0x10000 firmware.bin

all on one line, and once you’ve changed COM9 to the name of your serial port.


When the tool connects, it sends a message to the ESP and waits to be invited in. It prints a little progress bar like this while it does so:

If it gets to the end of the line then it’ll time out. Try that a couple of times, but if it doesn’t take on it’s own, use a cocktail stick to push the little BOOT button next to the micro-USB connector, and it’ll bump it into a upload mode.

Press reset to get back running again!

Well that happened fast

I posted a note out to the mailing list ( to add yourself) announcing that the first eleven machines were in stock (, and within two hours they had all been claimed!

I was amazed and encouraged and excited, because I was rather expecting that most of you would have given up waiting after getting almost a year’s-worth of “maybe next month” from me… So I’ve got a few left of that first batch still to pack up and post out, and then I need a bit of a pause to wait for some more lasercut parts to come in (congratulations to my lasercutting lady for her new baby – I can’t really complain too much about that delay!).

I got a big shipment of power supplies earlier this week and have half a dozen machines-worth of parts absolutely ready to go, bar acrylic cases. I’ll list those as soon as I can, and send a note out on the mailing list to those who have ticked the “tell me when you have stock” box.

Subscribe to the mailing list to be notified. If you’ve missed out this time around, please be patient. I feel very confident in this new design.

Software updates

The machines are shipping with firmware v2.0.1 onboard. This is more-or-less feature complete, matching what the old MEGA-based PolargraphSD could do. The main thing missing is the Norwegian Pixel style.

I’ve since worked up firmware v2.1.0 which reinstates the Norwegian Pixel style and also adds menus and buttons to the onboard touch interface to change machine size directly. It can also change the page size and position. This doesn’t really do anything yet, but I’m going to put a bit more thought into how the machine gets used in practice, hopefully helped by my beta testers Patrick (Wagner – Blackheart Press) and Chris (Bazant-Hegemark who will be testing this out in a workshop for The Royal Institute of Art Stockholm soon.


Since starting shipping I’ve already discovered an irritating issue where a 160 second pause randomly appears while drawing. It seems to be limited to USB traffic (I mean it doesn’t happen when drawing from SD card), and it doesn’t actually crash, it just stops to think for a couple of minutes. I’m sure this is a timer overflow or something like that, but these microcontrollers are hard to debug. That’s my number 1 priority because It Is A Stinker.

The future

Current roadmap:

  • Able to set up and specify a machine fully using the touch UI
  • Use millimetres to describe all dimensions (uses an odd mixture of mm and steps at the moment, which makes it very dependent on the physical motor setup)
  • Integrity checking: Emit warnings when the machine that’s specified in the controller doesn’t match the machine that is connected (this mismatch is the source of a lot of problems)
  • Specify and start drawings from raw image format rather than using the controller to build a queue first
    • Bitmap format drawn using norwegian style (for instance)
    • Vector drawing from raw SVG (but how to deal with shading/fill?)
  • Endstops for self-calibration and encoders for reliable long-term drawing

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