I really like this PSRAM chip from Adafruit. It behaves very much like SRAM, but with a much higher capacity and an SPI interface, which is so much nicer to deal with than more address lines than I can count. Hauling that much data back and forth with (Circuit/Micro)Python over a microcontroller SPI interface isn’t fast, but having that much capacity at your disposal makes it really useful.
I wrote a MicroPython driver for it a little while ago and have put together a CircuitPython version. I’ve tested it with CircuitPython 6.2, 6.3, and 7.0.0-alpha.3, and it seems to work pretty well.
Firefox has been my browser of choice for over fifteen years now. I’ve repeatedly donated to Mozilla and have enjoyed the security, stability, and “Firefox-ness” of the browser.
Times and technologies change, though, and while Firefox has on occasion irritated me (the change to “Quantum” a few years ago, for example), I think today is the first time that they’ve put out an update that actually strains my eyes. I present to you Firefox 89.0:
Aside from resizing, this image has not been manipulated in any way. Not a lot of contrast there. Here’s a different view:
Note how there’s nothing dividing the tabs and they all just blur together. I routinely have 25+ tabs open in a browser and this update isn’t going to make that any easier. I need glasses for distance and close work, but not for computer work, and I find this new UI hard on my eyes. I wonder how the changes will impact people with impaired vision.
Fortunately, Mozilla/Firefox has a way to submit feedback about their product so I thought I’d leave my thoughts about the new design:
Considering that they just released a new version, I’m guessing that “We’ve paused submissions to this form so that we can improve how we collect feedback” actually means “We’re being buried under an avalanche of comments and can’t keep up”.
I understand (and agree) that things need to evolve. After all, we’ve come a long way from this (which, interestingly, is ALSO all grey but makes my eyes ache less and I find it a lot easier to pick things out from the menus and bars):
But I think the Firefox developers dropped the ball on version 89.0. Hopefully the next update will bring some contrast, or at least menu options so folks like me can tweak some UI settings and make it a bit easier on our aging eyeballs.
Up until a short while ago, I’d never heard of EERAM. When I saw it, I initially thought it was a typo, but after looking into it I was pretty intrigued.
Turns out it’s SRAM and EEPROM packaged in the same device, and you get the benefits of both. During regular operation, you read and write to the SRAM, which means it’s nice and quick and has unlimited write cycles. If power is lost (and you have the right capacitor connected to the Vcap pin), the contents of the SRAM are automatically written to the EEPROM. When power is restored, the contents of EEPROM are automatically read into SRAM.
You can’t use the EEPROM directly, but you can trigger the device to store the SRAM data to the EEPROM with a command or pin, and you can recall the EEPROM data to the SRAM with a command.
It’s kind of strange but neat at the same time. Oh, and it shows up as two devices on the I2C bus! Weird, eh?
I put together a little MicroPython driver that sets the device to auto store in the event of power failure (so you’ll need that capacitor), and added functions to manually store SRAM to EEPROM and recall EEPROM to SRAM. If you’re interested, you can find it at: https://github.com/MarksBench/mb_47x16
I’ve been looking around for a generator for a while now, and Ms Geek just happened to come across one that someone had placed in their yard, hoping it would go to a good home. She was nice enough to pick it up and store it for a while until I could go pick it up (thank you!). This afternoon I gave it a quick look.
It’s… well, it’s seen better days:
A bit of rust on the muffler, some oil that’s hopefully from the air filter and not the crankcase, some dust, a couple dents. Okay, it’s worn, but not too bad. Should just need a good cleaning and a few new parts. Let’s see…
Okay, a little more rough than the back. More rust, missing bolts, and lots of cracked plastic. Still, with a little time and the right tools, I should be able to…
Methinks this has met the ground whilst in free-fall at least once. Or perhaps it got dragged behind something. Astonishingly, the front panel is beat to shit but the meter still looks mint. Maybe someone replaced it already.
Looks pretty oily and grimy in there. Still, it seems all the pieces are technically there.
I took the cap off the gas tank and was pleased to find the tank wasn’t half-filled with thick, stale varnish. In fact, what I could see was dry as a bone. A bit of rust here and there, and some top-notch quality welding:
When Ms Geek found it, it was sitting out all by itself with this sign held to it with a piece of twine:
Hopefully the first line is accurate – the rest of the sign sure is. Still, it looks like an earnest little machine that has most of its parts. Plus, it has a red fuel tank and I do like red things. So over the next while I’m going to pull it apart and see if it’s going to work (and not fog the entire neighbourhood with blue smoke), and if it looks hopeful, I’ll get to cleaning and fixing it. Regardless of how it turns out, it’ll be fun!
I’ve only used it with a Raspberry Pi Pico (RP2040) since that’s the only MCU I have that’s running MicroPython, but it should work with other MP-capable devices that can use a hardware or software SPI bus.
Writing and reading 64Mb over SPI is not fast, but it works!
As I’ve said many times, I’m not much of a programmer. But, on occasion, I cobble together something that I find useful. Ms Geek suggested a few times that I should throw that stuff onto GitHub so others could use it, even if it’s to give them a good laugh.
So… here we are. It’s been a little over a week since I started this project. Lots of ups, downs, laughs, tears, fist-shaking, face-palming, thumbs-upping, head hung in defeat, and arms raised in victory. I gave up on the Raspberry Pi Zero/Arduino combination (curse you, Timer3!!!) and switched to a Raspberry Pi Pico microcontroller (which, aside from making an LED blink by copy-pasting an example a few months ago, I knew nothing about) and started the electronics from scratch. By yesterday evening, things were moving along again. And in the end…
It was pretty close, though. By this morning, my little robot could move around on its own and successfully detect and turn to avoid (some) obstacles using an HC-SR04 ultrasonic rangefinder. I was working on LED rangefinding and cliff sensing when I ran out of time.
Head bowed and properly ashamed, I told my wife that my robot sweeper wasn’t ready. She assured me that it was “cute” and thanked me for not setting the house on fire. Then, a twist: she’s been doing a ton of research into the little robots and based on the layout of our house and the stuff we have kicking around, she’s not sure which one would be a good fit. We even talked about getting a (gasp) cordless stick vacuum instead. Personally, I’d still rather have a robot because neither of us enjoy vacuuming or sweeping (does anyone?) and it’s more likely to get done if a computer does it.
Regardless, the sale is now over and we didn’t buy anything. Which means… I have more time. It’s not really a challenge anymore since we don’t know when the next good sale will be (or even what we want) but as it’s been quite the learning experience and we both agree that having a cheap little sweeper robot can’t hurt, I’m going to keep working on this project.
I have also “discovered” the Pi Pico. I’ve had a couple of them for a while now but since most of the stuff I do is with an Arduino, they’d been sitting around until I had time to tinker with them. Well, in the last 48 hours or so I’ve tinkered with them until my eyes would no longer focus and I’ve got to say that I’m quitepretty extremely impressed. Setting up MicroPython was easy, it’s easy to program with Python, and it has so many peripherals built in (not to mention the PIO stuff which I haven’t tried but looks great) that it’s… well… pretty amazing. And I’ve barely scratched the surface. I’ve got a million other project ideas for it, and it could well become my go-to when I need a microcontroller for something.
With the time constraint relaxed (at least for now), I’m very interested in seeing where this project goes. But now it’s late again and I really, REALLY need to clean my piles of components, wires, and papers off the dining room table before I go to bed.
I thought I had everything figured out. Raspberry Pi Zero was going to talk over I2C and a level shifter with two Arduino Pro Micros – one for sensors and one for motors.
Rangefinder and LED/phototransistor pairs were working great and reporting nicely back to the Pi over I2C.
I wasn’t worried about the motors because a couple of days ago I had the drive motors working when sending commands using the USB serial on the Arduino (that’s what I was doing in the video from the other day).
But alas, the USB serial port uses timers differently than I2C on the Arduino, and the servos and I2C are arguing over the same 16-bit timer hardware in the 32U4. There is one other 16-bit timer on the chip (Timer3) but when I tried using it instead of Timer1 for the servos it doesn’t have the same kind of access to the pins that Timer1 has.
I think, anyway. The best I could get out of the servos was an occasional irregular “putt”. And now it’s getting late and I’ve spent way too much time staring at datasheets. Oh, and of course when I went to the Arduino forums I was greeted with this today:
I know there’s a solution, but my old worn-out brain can’t think of it right now. I guess I could run the sensors over I2C and the motors over UART, but I was hoping for a cleaner, less confusing setup. A different microcontroller? ESP32? Pico? Ehurrrghhh.
At any rate, I need to get to bed. Lots of stuff I’ve been putting off that I should really do tomorrow before I get back to work on this particular project.