I have been playing with the Nordic Power Profiler again today. I'm doing some SD card benchmarks. Not for any real reason but I'm curious.
As well as the speed, I was interested in the power use. Here you can see writes (on the left) using more peak power than the reads (on the right). However, unexpectedly the writes use less overall power. I assume this is because the code I'm using leaves the card in a different state between reads. The writing does a file.flush(); inbetween each test, so I will investigate if this is what's at play.
This is exactly what I bought this thing for.
Also it's a bit like having a tiny bench PSU connected to your computer with USB. I have used it to replace a 3.7v LiPo battery, direct 3.3v supply to a microcontroller and 5v supply to a development board instead of USB.
I continue to be very pleased with it. Only grumble so far is the 'digital channel' display only shows when looking at 3s or less of samples. If you're using pins on a microcontroller as a low speed 'status' indicator rather than for busier signals this is not helpful.
Given I've been doing a lot of work recently that involves assessing power consumption, I saw a timely video from Adafruit looking at the Nordic Semiconductor Power Profiler II.
I've been sticking cheap INA219 modules into my various stripboard prototypes and exporting data every minute over MQTT. These are great for broad, macro scale measurements over a long-ish period.
What they can't however do is measure down to the resolution needed to assess how efficient deep sleep is and whether changes to code reduce the time spent transmitting or waiting to receive data over WiFi. The former is very power hungry and must be minimised to save battery. The latter might be tuneable to help.
Professional equipment to do this is really quite expensive. The newly released Power Profiler II kit from Nordic is in the hobbyist friendly price range of ~£100. Mildly extravagant and you could perhaps roll your own but this price point is not ridiculous given the time you'd spend building the tool if you want it to work well. Which is why I've treated myself to my first new tool of 2020.
I've got one of my old macro spreadsheets to analyse for the ESP32-S2 WROOM module, but after that I'll be using the Power Profiler to delve deeper into how much power my prototypes are using and if there's anything I can do to improve this.
Recently I treated myself to a Xiaomi Wowstick 1F+ as Banggood were doing big discounts around Black Friday.
These are a bit of a silly thing, a powered 'precision' screwdriver that's like a big fat pen.
Mostly they're very cute and come packaged like some kind of Apple product, all in separate little white boxes. They're the kind of thing that makes a cool gift for somebody who tinkers and even come with a carrying case that's like something from a sci-fi movie.
Notably the set I bought comes with many many high quality precision bits, perfect for taking modern consumer electronics to bits. I just used this to have the internal cover off my smartphone so I could replace the failing battery and it's already saved me from having to go and hunt a suitably small set of tools down.
There are a few variants available, I thought I was getting the one with a charging base but didn't realise this model was different, so check before order.
Having bought a CNC engraver I got very caught up in messing around with the optional laser module.
I'd previously not considered a cheap diode laser would be worth having, especially due to their reputation for rubbish software.
However once I'd played with it and set up Laserweb this changed my mind and I ordered a 2.5W A3 engraver. The 5.5W models are twice the price and probably not twice as good, online discussion suggests they are far worse at intermediate power levels which are useful for engraving. If the laser modules come down in price later I can always upgrade.
It's a much simpler machine to build than the desktop CNC, with steppers directly driving a belt and dragging a carriage up and down the rails. So I got it put together over an hour or so and simply connected it to my existing Laserweb setup. The drive ratios needed setting but apart from that it 'just worked'. Now I need to tweak things like the maximum speed and acceleration as it draws quite slowly but straight away I started to get usable output from it.
Here's a little video of it engraving at max 25% power. This burns really well so I'm thinking 100% will cut some thin stuff quite nicely, just need to start experimenting.
My experience with the laser module in the desktop CNC has made me less paranoid around it, which is probably a bad thing. So I'm going to set this aside until I can find some time to make an enclosure with a safety interlock on the laser power. I'll just stick a normally open switch inline with the 12V power so the moment you lift the lid the steppers and laser get cut. The microcontroller onboard takes its power from the system driving it.
It'll have a Raspberry Pi inside to run Laserweb so hanging a Webcam off this to give an internal view when the lid is closed should be trivial. I quite fancy making a bit of a control panel on the front to control the Pi and also control power to the laser perhaps via a GPIO driven relay so the whole thing has a single on/off switch but this is verging on yak shaving.
I've been playing with the CNC engraver and discovered a few things. First up is the controller is based off an Arduino Nano running open source code (grbl) but running an older, stable version (0.9). Another is that the z-axis was miswired, even for the software it shipped with, so I had to reverse the pins on one end of the z-axis cable. It's possible to fix this in software but it irked me.
Somebody from London Hackspace pointed me at LaserWeb as a good front end to the laser engraver side of things so I've started to investigate it.
Converting these Chinese laser engraver/cutter devices away from the slightly cheesy software they ship with to open source is a common question and an Australian woodworker has produced a breezy intro to doing this. It's for a different device but the fundamentals are the same.
The LaserWeb server will happily run on a Raspberry Pi and I've several sitting in a box. After a couple of hiccups going through the howto it's up and running. This needs a newer version of grbl so I've programmed the Nano in the controller with grbl 1.1e. It's easy to put the original software back on as part of the original CNC build is to program the Nano with a file they provide.
A big gotcha I did find is that the LaserWeb GUI needs ALL the components to be working. So if you try to use the interface and it's displaying error messages, particularly relating to WebGL, in the bottom right log window it just won't work at all. It looks like there is a server error because it says you can't connect but this can be down to the graphics library as it breaks a load of things in the app, not just the graphics previews. A very helpful person from the LaserWeb3 support comunity on G+ helped me work this one out.
Now I was down the rabbit hole of playing with the laser side of things I decided I wanted to be able to work safely while testing and sticking the whole thing in a box was going to make that irritating. I've got a load of cheap ~5mW laser pointer modules kicking around so I 3D printed a 'dummy' housing the same size as the 'real' laser module and fitted one of these.
This left me free to mess around without blinding myself or starting a fire. The laser may only pack a 500mW punch but that's enough to do both these things.
Having proved to myself that the thing wasn't going to smash into the end of its travel and LaserWeb turned the laser on and off reliably in a fashion that looked like it was going to produce sane activity instead of just melting something I didn't want melted I had a go at the real thing.
I found an .svg of the Coke logo on Wikipedia, scaled it appropriately in the LaserWeb interface and started burning. At first this had zero effect and I was wondering if the laser module was defective. As I had a box over the whole thing to prevent any chance of blinding myself I couldn't really see what was going on.
I don't really trust the cheap laser safety goggles I got from Banggood. I had a webcam pointed at it but the laser simply oversatured the picture so I couldn't see much.
Using the 'test laser' button in LaserWeb, which runs it very briefly at minimal power, with the box removed I could see the beam was totally unfocused. There wasn't any obvious way to fix this, but some experimental twisting of the module showed it can be focused. This is not obvious at all and not mentioned in the minimal documentation. Once adjusted carefully to make a tiny bright spot it engraves random wood quite nicely. This Coke logo was done by running it quite quickly doing multiple passes. I need to experiment somewhat with the engraving speed and at some point try to cut some thin material.
In principle LaserWeb has a 'CNC' mode too where it will handle CNC milling/engraving which I'll investigate as it would be nice to use the same software for both jobs. The more I play with this though the more I think I want some limit switches so it can home itself automatically and definitely prevent crashing into the end of travel this is a bit of modding that shouldn't be too hard to do.
I've had a good evening of mostly tightening M3 nylocs. Eventually after about three hours my desktop CNC engraver went from looking like the first picture to the second one.
There were only a couple of moments of retracing my steps. The set of picture instructions you download were OK. However they've changed the design slightly and substituted some fasteners so you run out of shorter ones if you use them everywhere they suggest.
I've no idea if it works at all as I haven't powered it on, let alone installed the software. This is a job for tomorrow evening.
It's been a while since I posted. Mostly I got involved in running a LARP, which sucked a lot of my energy through August and September then suddenly it was Christmas.
Speaking of which, my present to myself was one of these tiny desktop CNC mill/engraver/laser machines from Banggood.
It's taken me a couple of weeks to get around to ripping the box open and here it is. It's going to be a smaller, simpler project than my 3D printer to assemble but I suspect it'll still take a while.
It's a curiosity in that it can do both engraving using a cutting tool and with a laser that fits in the same mount. The laser is only 500mW so it's not going to be cutting anything but I reckon for surface marking stuff it'll be great.
Right now I'm building a 'disposable' PC to run the accompanying software as I don't trust it not to be flaky and/or virus infested.
