Thoughtophone

I figured my daughter might like to learn to fly a quadcopter during lock-down. Ages ago, I printed this frame , and bought an F3 2.0, a set of brushed motors, and some batteries. It's all just been sitting in a drawer. I need a receiver, though. It seems a lot of people do this using an NRF24L01+ and an Arduino. In fact the two have even been combined in a single board  by someone enterprising. I decided against the Arduino, because the cheap ones need 5V, and the quadcopter is powered by a single lithium battery. Also, the Arduino has limited PWM resolution. So at this point I was considering a black pill I had lying around, but it weights 6g, vs 2g for an Arduino pro micro. Then I thought about an stm32f411 black pill, which weights 2g like the pro micro. It turns out the flight controller includes a boost converter to power 5V 'peripherals' so that eliminates that argument. It's also controlled by a serial port rather than PWM, so I don't have to worry...

The original idea for this came from hacking a dell power adaptor , which I found after taking my laptop to Australia and finding the USB-C PD to dell adaptor I took with me would power my laptop, but not charge it. I ordered some 3-wire cables on e-bay and resolved to try this at some point. I'm now in the process of building a dock for my laptop, in which I've used one of the 3-wire cables. Before that can be any use, I've got to get this working. There's a one wire library called  OneWireHub  which includes a  sketch specifically for emulating a dell power supply . It's easily the best example, with a clear menu of power supplies to emulate. OneWireHub can be found in the Arduino library manager. I was going to use a Digispark clone, but the OneWireHub library doesn't compile in the Aduino IDE (or in the eclipse arduino plugin for that matter). That's because they both use an older GCC version for the ATtiny85. I suspect there's no reason for th...

I want to become fluent in Rust, and I have a few things I'd like to do with embedded systems, so I figured I'd combine the two. This has got a lot easier since I first thought about it: there's a book . The thing I specifically want to do is regularly sample the ADC, using non-blocking APIs. This is sort of supported: There are some standardised HAL API s, and they use nb  which is a generalised non-blocking mechanism. This does mean, however, that you end up needing a spin loop that tries everything you are waiting for. You can handle interrupts, so perhaps there's a sleep function that wakes up after an interrupt has been processed? Then I could add something like Chibios events: the interrupt would set the right event flag, and the main loop would act on each event flag that was set, each time it woke up. I don't need to do this, because the RTFM framework does it already, and statically analyses your program for deadlocks. RTFM lets you define '...

EspDRO  uses the ESPs ADC to avoid needing a level converter to receive caliper data. This makes me think I could do even better using STM32 ADC and Chibios: efficiently reading several calipers at once. I got out the calipers I'd previously soldered wires too, and promptly managed to break the wires off one. There are several connectors on Thingiverse now. I think I better print one. I found the EspDRO link in this one .

I never did get around to upgrading my circular saw cross cut jig for thicker material. Anyway, I found a Youtube video describing how to make one out of wood that I'm pretty sure I could get right, because it allows you to build the miter bar separately, and has a pretty fool proof way of setting it square. It's in two parts. The first makes the frame: and the second shows you how to make the guides: The whole channel is fascinating . I can't find anything like the window frame extrusion used in the videos. That would give pretty ideal results given my height limit of 10mm, but I guess what I got to work last time will work again: I just won't be able to make it any longer than last time. There are loads of good ideas here. I can't figure out exactly what some of the parts are, but I think I can figure out some equivalents in all cases.

I bought a brush-less fan PFB1212UHE  for £14. It seemed like a good deal - I was mostly concerned with the air flow and static pressure. It would have been better to buy an AC fan, because I need a 60W 12V power supply to control it. That's going to double the price... At one point I also thought I was going to need a brushless motor controller, but it just runs on 12V, and has an output signal which is one pulse per revolution. I guess that makes variable speed control relatively easy. It really is a powerful fan! It weights 380g and can levitate a couple of millimetres off the desk.

I've been wondering what I might do to control air quality in my very small shed. It's 1.5x1.8x2.1M, or 5.7 cubic meters, or 200 cubic feet. If I was just going to buy something specifically for this purpose, this WEN air filtration system costs £112, and would suck all the air in my shed through it twice in a minute. It's not massive - 50x45x25cm, but it would help if it was smaller, and it's noise isolation requires it to be hung from the ceiling, which I can't do if I don't want to bang my head on it. Lots of people have posted on YouTube on how to make air filtration systems using box fans. They are generally scaled up compared to the WEN, rather than down. This video points out why using a box fan isn't that good an idea. It's a rather over-complicated solution though: you can just buy a plate fan that includes a baffle. I suppose it's great if you have a fan you don't want. This video is the only attempt to make something signifi...