Repurposing the Nook Simple Touch

A long time ago my brother and I were gifted a pair of Nook Simple Touch e-readers but eventually Barnes and Noble abandoned the UK market and they ended up as drawer cluttering e-waste.

However they are actually quite interesting devices and a small community has built up around modding them so they can be used more freely. They're very low power Android tablets with Wi-Fi, an excellent e-ink touchscreen and five usable buttons round the edge.

So I dragged them out of the drawer and went through a tutorial I found to see how they behaved.

Once rooted and with the new launcher installed they work just fine and I found a few more tips online to make them more usable. No, I've no idea what they'll get used for yet but they can run things like the SSH client ConnectBot if you pick an old APK.

Supposedly with the new kernel I've uploaded which will make plugging in a keyboard etc. possible so they might make for an interesting low power terminal. They don't have the CPU or RAM to run a modern web browser, but the one on there is OK for minimalist web apps.

Creality Ender 2 fixed

I finally got my Ender 2 3D printer fixed. As I'd diagnosed, there was a near short in the heater cartridge and I've now done my first test print after replacing it, which came out perfectly. Absolutely no fancy tuning, just level the bed with the thumbscrews and a piece of paper then press print on the test file on the supplied SD card.

There are a few surface blobs but for a zero effort test print I couldn't have asked for more. Definition on the Chinese characters is excellent. I also lined up a Benchy and it came out pretty well but it did take a while to print so wasn't any kind of speed test.

This little £100 printer is so impressive, it seems a shame they aren't widely sold any longer. I know the Ender 3 is nominally upgraded but the Ender 2 is already a sufficiently good 'first 3D printer'.

I can see myself using this a whole load, as my Ormerod is still sadly kind of unreliable.

The Ender 2 prints from an SD card, but I'm used to having remote control and monitoring of my printers over the network. To fill the gap I've set up Octoprint to drive the printer directly from a Raspberry Pi, doing away with the need for SD cards.

Octoprint is widely used and I've worked with it on the Hackspace 3D printers before but as my other printers have network interfaces this is the first time I've used it in my own workshop. The fact it adds support for a USB camera to observe printing is a nice extra. I used to do that with a standalone camera setup on the Ormerod. For a slicer for the Ender 2 I'm using Cura as that's well integrated with OctoPrint. By adding a Cura plugin you can send files directly to the printer and monitor progress, including getting a a nice view from the camera.

The external PSU, Raspberry Pi and so on makes for a slightly untidy setup so I will make myself a little stand base to put the extra clutter in.

Oh and it makes the proper 3D printer sing-song stepper driver noise. Ever since I upgraded my Ormerod to a Duet 3D with Trinamic drivers it's near silent and I'd missed the noise.

Just listen to it...

Presentation at Raspberry Pint September 2019

I recently gave a talk at Raspberry Pint about my mesh networking project. Nominally this is a Raspberry Pi meetup but they're happy to cover various tech and maker subjects and I've spoken there a few times before.

I'm reaching the stage where my code can be demoed and hopefully released soon.

Annoyingly, I managed to damage the Wemos D1 mini I'd brought with me to show the chat application demo on the projector but it worked on the netbooks I handed out.

ESP32-CAM breakout

While I'm waiting for a Brian Lough to make a proper breakout board I scratch built one for the fantastic ESP32-CAM board.

It's a bit ugly but it lets me program these up easily while I'm testing my code. The reset line isn't brought out on the headers. So you have to push the button on the underside of the module while simultaneously pushing the 'program' button I put on the breakout. Fiddly but it works.

Something I've also noticed is that if you use a Sparkfun 3.3V FTDI basic board to power the ESP32-CAM 3.3V line directly you get awful problems with power brownouts. This means that you might be able to program the board but it won't reliably boot and work. This isn't surprising, the board needs quite a chunk of power.

So I'm using a Sparkfun 3.3V FTDI basic with the power link changed on the back to 5V. This connects the 5V from the USB straight through to the device. The logic level is still 3.3V, so you won't kill the ESP32.

Ender 2 troubleshooting

To my shame I have left my DOA Creality Ender 2 to lurk in a corner pretty much ever since I got it. I managed to get a replacement PSU as it cut out when the hot end started but it just behaved the same with the new PSU.

My attempts to follow this up with the seller turned into a wrangle with them wanting me to contact Creality for support and I ran out of enthusiasm as I was busy and I had fixed the other printer. I just never take my own advice about not accepting repairs on new goods instead of demanding a replacement. One day I'll learn.

This weekend is quiet so I pulled it out and had the cover off the controller. It's a really easy printer to work on, just undo the three outer screws on the cover and it pops off giving you easy access to the board. I know it's never actually worked but I'm still impressed with how nicely this is put together for the money.

As I suspected, with the hot end heater cartridge disconnected the printer no longer cuts out when you apply power to the hot end. The heater cartridge isn't a dead short, but it's only about 2 Ohms.

To test things further I connected a 35W incandescent 12V light bulb to the heater terminals and everything works fine, so the board and PSU are almost certainly good.

I've now got a replacement hot end on the way, thankfully parts for these are dead cheap. You can get better quality upgrade parts for the Creality printers but when a good hot end is as expensive as the whole printer I'm unconvinced of the worth of this. Everything I've seen from other owners is that the stock hot end is perfectly adequate.


I bought this weird "WeMos Mega" combo board from Banggood on a whim. It's an Arduino Mega 2560 clone with an onboard ESP8266. They both operate independently but you can flip some DIP switches to connect the serial pins together allowing them to send messages back and forth. I assume there's some level shifting onboard to match the 3.3V/5V levels too. You don't have to link the two processors, they can in principle leave them disconnected although with a single USB serial you still need to use the DIP switch to set which one you're programming.

As the Mega has four serial ports it gives you the option flick a switch and connect the ESP8266 to Serial3 leaving Serial0 for USB comms/programming the Mega. There's also a separate pin header giving you access to the ESP8266 pins directly.

This is either the best of both worlds, or the worst of both. I've got a project coming up where I would like to use a few more pins than an ESP8266 has as standard and I grabbed it for that. It could easily be argued an ESP32 board with all the pins broken out would cover the same ground.

What's the target market? I'm unsure, I guess people who are used to old-school Arduino kit and want to use the ESP8266 in its somewhat old-fashioned role as a Wi-Fi co-processor rather than as the really useful microcontroller it is in its own right.

Anycubic Photon

I randomly saw a Twitter acquaintance posting about how these SLA printers were currently on offer direct from the manufacturer and couldn't resist.

My now incorrect world view includes SLA 3D printers being too expensive for casual hobbyists to buy and I'm glad this has changed.

As of Autumn 2019 you can pick one of these up for ~£275, which is around the same price as an effective FDM printer like a Creality CR-10. The build volume is tiny but if you're buying an SLA printer for the surface detail it can handle you probably aren't making things much bigger than would fit in the palm of your hand anyway.

A good thing about these specific printers is they are a few years old and have built up a strong community around them. This is helped by the fact it's a based around a generic controller board made by CBD Technology meaning it's not 100% locked to support by Anycubic. There is a newer AnyCubic Photon S which isn't markedly improved and suffers from having to use a proprietary slicer from AnyCubic.

The community has a lot of advice, tips and mods and one of the first things I did was to enable the onboard network port which allows you to upload things to the printer over the network. The Duet3D board in my old RepRapPro has spoiled me and messing around with swapping USB sticks or SD cards to provide files for printing seems quaint.

I don't have an immediate clear use for this but there have been times in the past where I want to print something small and detailed that my FDM printer can't manage. The first thing I'll probably try is some custom keycaps for some small handheld devices I would like to make.

These cheap SLA printers work by having a very thin flexible non-stick membrane in the bottom of the vat of resin. As each layer is printed, the plate moves up, the membrane flexes and this peels the print off this membrane. It's quite fragile and both the membrane and screen are considered consumables. So this won't get used for any high volume work.

Once printed the resin is not 100% cured and a strong UV source is needed to finish the job. I've left my test print in the sun for a few days, but I'll need to sort myself out a small curing cabinet.