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Teensy 4.1 Development Board

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Re: Teensy 4.1 Development Board

#111

Post by comboy »

dekhn wrote: post #107
comboy wrote: post #101

Earlier quoted context omitted.

From coin cell battery you can power a microcontroller that is sleeping most of the time, not a real-time operating system.

You can do exactly this with an ESP32. It's got an RTOS (FreeRTOS) which will spend most of its time sleeping https://learn.circuit.rocks/esp32-deep-sleep

Debatable. Personally I would not try to do a project that uses wifi on a cell battery. And if you don't need wifi then you have much better options that use low current not only while sleeping (e.g. nrf series)

But my main point which I should have included in the previous reply was - what does real time OS have to do with the project being run from a cell battery?

Re: Teensy 4.1 Development Board

#112

Post by dekhn »

I've worked with all the various Arduino and other MCU boards as well as Pis. My preferred chip is still an Arduino Nano in a screw terminal carrier (just today I wired up one to make a rotating stepper that rotated in sync with a camera trigger, to do 3D scanning for Meshroom).

I love the old Uno, it's solid as a rock but of course has very limited CPU and memory. I would only use an Uno if I had a specific shield that fit the Uno and needed 100% compatibility. The dupont connectors are too loose for permanent projets that get shaken around... it's 5V, which makes working with some hardware easier (although most things "kinda work" with 3.3v MCUs, some stuff doesn't).

The Nano is like the UNO but smaller, although you can get nice little screw terminal carriers that make permanent connections more reliable.

The Teensy is a faster arduino with some very good support libraries. It Just Works, most of the time. But I haven't ended up using it for anything; I've replaced it with Nanos or ESP8266 or ESP32.

The ESP2866 and ESP32 are great systems, truly amazing what they can do even if they're just emulating an Arduino. however, there is a fair amount of compatibility problems with the 32 (for example, I have a sketch for a self-balancing robot, it works fine on Nano and ESP2866, but hangs on the '32). But the 32 has a special trick up its sleeve: the arduino functionality is really just an emulator that runs inside an RTOS. I started to play with FreeRTOS on ESP32 (https://docs.espressif.com/projects/esp-idf/en/latest/esp32/...) and was really impressed. It feels a lot like my days using a 286- no virtual memory, a few megs of RAM, and basic networking.

Re: Teensy 4.1 Development Board

#114

Post by realharo »

comboy wrote: post #111
dekhn wrote: post #107

Earlier quoted context omitted.

You can do exactly this with an ESP32. It's got an RTOS (FreeRTOS) which will spend most of its time sleeping https://learn.circuit.rocks/esp32-deep-sleep

Debatable. Personally I would not try to do a project that uses wifi on a cell battery. And if you don't need wifi then you have much better options that use low current not only while sleeping (e.g. nrf series) But my main point which I should have included in the previous reply was - what does real time OS have to do with the project being run from a cell battery?

So my assumptions in the original question a number of comments above (in the context of the comment above it) were:

- something running regular Linux would be too heavy (though I don't know if that's really the case, especially if you only turn it on a few times a day on average for a little bit)

- adding the "OS" abstraction would presumably result in access to higher quality ecosystem of libraries than whatever is available on bare metal directly (as I assume some of those libraries depend on the "OS" for event handling etc.) - which was the complaint in the comment I was replying to

But like I said, I know very little about this area, so if any of this doesn't make sense, just ignore my comment :D

Re: Teensy 4.1 Development Board

#115

Post by wolrah »

angst_ridden wrote: post #105

The Teensy line is great for folks like me, who are doing one-off projects and who know more about software than hardware. There are good libraries, a helpful developer, and a supportive community. I've used Teensies to make millisecond-accurate camera controllers, radar-triggered music/light-show devices, and burning-man style LED hats. If I were doing production, they'd probably be overkill (and too expensive), but…

Yup. I love Teensies for building USB input devices. It's trivial to get something basic working and not much harder to tweak it if you want to appear differently to the system or use a higher refresh rate for lower latency gaming.

They're breadboard friendly, as easy to use as an Arduino, etc. For one-off builds that need lower power or tighter timing than I can achieve with a Pi I pretty much default to looking at the Teensy line unless I need some kind of wireless communications, in which case an ESP variant is usually my choice.

Re: Teensy 4.1 Development Board

#116

Post by MrBuddyCasino »

ohazi wrote: post #82

PSA: Networking on microcontrollers is a giant pain in the ass. Don't get me wrong, boards like this (and ESP/Realtek boards with WiFi) are great for hacky prototypes. But if you're building an embedded device that will be deployed in any sort of volume, a small application processor running Linux will make your life dramatically easier. You can keep it asleep most of the time if your power budget is tight. The hard…

But what to use? The Pi Zero can't be used for mass-production, because you can't get it in quantity. Other options exist, but they are even more expensive, or obscure chinesium for which you can't get documentation or someone to talk to.

Re: Teensy 4.1 Development Board

#117

Post by HeyLaughingBoy »

comboy wrote: post #96
realharo wrote: post #84

Earlier quoted context omitted.

How are things on the commonly used RTOSes? I'm not really into hardware much, only fairly recently learned basic electronics as a hobby, but I've seen ARM push their "mbed" ( https://os.mbed.com/ ) thing in many places recently (most recently saw their logo printed on a nRF52 BLE dev kit). I've also seen Amazon get more involved with (in charge of?) FreeRTOS ( https://aws.amazon.com/freertos/ ) quite some time ago.…

I wonder what's your use case for RTOS? I don't really know any problems that couldn't be solved with micros communicating with linux. Seems like even SpaceX gets away with it. I mean there seem to be the market so clearly there are some people who need it, I just would like to learn more about where is it really needed.

It's not that the problems couldn't be solved that way, it's that they don't necessarily get any simpler. Adding an external micro and all the support it needs is added cost, maybe added real estate, power budget and very often, it makes the solution more complex and less reliable.

Re: Teensy 4.1 Development Board

#118

Post by MrBuddyCasino »

yjftsjthsd-h wrote: post #3

Generally a very nice addition to the lineup. I'm personally fascinated by the support for soldering on an additional RAM chip; depending on how painful it is to actually access that memory, the extra 8MB could finally be enough to run uclinux.

The ESP32 can do that too. Note that PSRAM is a lot slower than the embedded SRAM, so if you need to access that memory a lot, you're going to have a bad time.

Re: Teensy 4.1 Development Board

#119

Post by joefourier »

MrBuddyCasino wrote: post #116
ohazi wrote: post #82

PSA: Networking on microcontrollers is a giant pain in the ass. Don't get me wrong, boards like this (and ESP/Realtek boards with WiFi) are great for hacky prototypes. But if you're building an embedded device that will be deployed in any sort of volume, a small application processor running Linux will make your life dramatically easier. You can keep it asleep most of the time if your power budget is tight. The hard…

But what to use? The Pi Zero can't be used for mass-production, because you can't get it in quantity. Other options exist, but they are even more expensive, or obscure chinesium for which you can't get documentation or someone to talk to.

If you want an decently peforming SBC that can match the Pi Zero in price, unfortunately you're out of luck. But if you're willing to put in a bit of work, make your own board and suffer most things not working out-of-the-box, you have a wide variety of cheap SoCs and MPUs. E.g. the STM32 MPU line, which has a decent enough ecosystem and plenty of devboards available, and has some chips under $5/unit in bulk.

Re: Teensy 4.1 Development Board

#120

Post by elihu »

cpach wrote: post #6

Just out of curiosity, what could be a use case for this thingy?

It can be used for just about anything you can use a microcontroller for, but it seems particularly popular for art or music-related projects. For instance, audio synthesis, controlling large numbers of programmable LED strips, custom MIDI controllers, and so on.
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