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How to pick a microcontroller

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Re: How to pick a microcontroller

#91

Post by joezydeco »

dragontamer wrote: post #70
fragmede wrote: post #67

Earlier quoted context omitted.

If we're recommending pet favorites, the Raspberry Pi Zero Wireless, despite being the newest, is now my recommended "microcontroller". There are a few tweaks needed on top of the base Rasbian distro to make it appropriate for use as a microcontroller, but with a base price of $10, it's cheaper, more powerful, and has accessories (ie - anything USB with open source Linux drivers), than some Arduinos. Built in wifi, L…

I still consider that a 'computer' and not a microcontroller. You will inevitably need adc functionality, possibly real time clock and battery usage. Most servos don't need wifi or Ethernet. Instead, you will usually want to be able to read a voltage and then time how long it takes for that to change. 15 cent quartz crystal and built in adcs. Bitbanging pwm from raspberry pi is also horribly inaccurate... You need a…

It's also not something you can build a production device out of...unless your margins are so insanely large that you can afford it and nobody cares.

Re: How to pick a microcontroller

#92

Post by falcolas »

bigiain wrote: post #80
falcolas wrote: post #11

Now that you've picked a microcontroller, here's some tips on the next steps: "How to be: A smart hardware programmer" https://youtu.be/g8QDCMuy6oM I link to this only partially in jest - you really will need way more components than the plan says you'll need. Even microcontrollers; misaligning a header by one pin can result in things like putting the output of a 3C Li-Poly over a signal header...

This is why I like prototyping with Arduinos - you'll 99% likeley get away with plugging an 11.1V (or 12-13V fresh off the charge) battery into any of the pins on an Arduino. You'll be looking for another RasPi if you made _that_ mistake...

In this case, it wasn't the voltage, which had been brought down to 5v by the motor controller, it was the 160+amps. Not milliamps, amps (3300 mah, 50c battery).

Drone batteries are nasty pieces of work...

Re: How to pick a microcontroller

#93

Post by bigiain »

falcolas wrote: post #92
bigiain wrote: post #80

Earlier quoted context omitted.

This is why I like prototyping with Arduinos - you'll 99% likeley get away with plugging an 11.1V (or 12-13V fresh off the charge) battery into any of the pins on an Arduino. You'll be looking for another RasPi if you made _that_ mistake...

In this case, it wasn't the voltage, which had been brought down to 5v by the motor controller, it was the 160+amps. Not milliamps, amps (3300 mah, 50c battery). Drone batteries are nasty pieces of work...

Indeed.

I wasn't paying enough attention when soldering a plug onto a 7 cell 5800mAhr 40c battery once. I melted the tip of my iron, and pretty much vapourised the plug's contacts... (The battery seemed fine about it - I got 6 or 8 months out of it powering a bicycle before it started to show signs of imminently-firey puffiness...)

Re: How to pick a microcontroller

#94

Post by dragontamer »

joezydeco wrote: post #91
dragontamer wrote: post #70

Earlier quoted context omitted.

I still consider that a 'computer' and not a microcontroller. You will inevitably need adc functionality, possibly real time clock and battery usage. Most servos don't need wifi or Ethernet. Instead, you will usually want to be able to read a voltage and then time how long it takes for that to change. 15 cent quartz crystal and built in adcs. Bitbanging pwm from raspberry pi is also horribly inaccurate... You need a…

It's also not something you can build a production device out of...unless your margins are so insanely large that you can afford it and nobody cares.

Ehhhh... depends really.

You can easily spend around $10 on a single filter (ex: 8-pole Filter... such as https://www.digikey.com/product-detail/en/linear-technology/...). If you need an 8-pole elliptical filter, you just go out and buy one, amirite?

The "production" competitor to the Raspberry Pi Zero is honestly something like... the Octavo Systems OSD3358. At $50, you may wonder why this device is superior... but it has integrated RAM, Open Documentation, the features that are necessary for microcontroller work (ADC, DAC, PRU/Programmable Realtime Units, RTC, on-board LDO Regulator, on-board Lithium-Ion cell balancer and Lithium-Ion manager, support for TWO Crystal Oscillators, 114 GPIO, 6 UARTs).

http://www.digikey.com/product-detail/en/octavo-systems-llc/...

Its all about your REQUIREMENTs. The Raspberry Pi Zero barely does anything aside from computer things (Ex: WiFi, USB).

Don't get me wrong, the Raspberry Pi Zero is a wonderful computer. But microcontrollers are things that can work with Thermocouples, control Active Filters, and control motors. In contrast, the Raspberry Pi burns itself out if you put an LED on its weak GPIO pins... and even "Realtime" Linux can't save you from the micro-second delay associated with the GPIO pin hardware.

Re: How to pick a microcontroller

#95

Post by joezydeco »

dragontamer wrote: post #94
joezydeco wrote: post #91

Earlier quoted context omitted.

It's also not something you can build a production device out of...unless your margins are so insanely large that you can afford it and nobody cares.

Ehhhh... depends really. You can easily spend around $10 on a single filter (ex: 8-pole Filter... such as https://www.digikey.com/product-detail/en/linear-technology/... ). If you need an 8-pole elliptical filter, you just go out and buy one, amirite? The "production" competitor to the Raspberry Pi Zero is honestly something like... the Octavo Systems OSD3358. At $50, you may wonder why this device is superior... but…

My point is that if I needed to build and sell 200,000 of something over 10 years, I can't order that many from the Raspberry Pi foundation and trust the piece will still be around the entire time. And if I wanted 200,000 of the Broadcom parts, they wouldn't sell it to me in that small of a quantity.

The OSD3358 is definitely the right approach, since putting high-speed impedance/timing matched DDR lines on a board to make it work right with a modern 1GHz+ CPU is a much higher level of difficulty. Plus you will also need to make your PCB 8 or 10 layers to shield the interference which increases the cost.

I thought package-on-package (like the AM335x's predecessor, the OMAP) was the way to go, but I'm starting to like the monolithic package better.

Re: How to pick a microcontroller

#96

Post by jwr »

jpm_sd wrote: post #88
jwr wrote: post #57

Earlier quoted context omitted.

Interesting -- could you write about your impressions? How do peripherals compare? I think you get 32-bit timers on the STM32? And I heard that most other peripherals are newer/better than the 8-bit peripherals that NXP/Freescale adapts to the Kinetis chips -- what do you think?

I guess I just haven't needed those bells and whistles. 32 bit timers are kinda huge. And some of the peripherals on the STM are suffering from "newer ain't always better" - the CAN and I2C controllers are more complicated than they need to be, IMHO. Edit: I can't make any useful comparison on analog peripherals since I use external ADCs, DACs, etc. more or less 100% of the time

Thanks, this reply is much appreciated.

Re: How to pick a microcontroller

#97

Post by antoniuschan99 »

kirrent wrote: post #73
MrBuddyCasino wrote: post #27

Earlier quoted context omitted.

"esp32 is not ready for prime time yet" There are some rough edges, but its already very useable, especially since the new silicon came out. Got anything specific in mind?

I just came back to my esp32 after a 6 week hiatus and the framework has evolved impressively in that amount of time. It's an awesome product for a steal of a price. Definitely at the usable stage.

That's great to hear!

If that's the case, then it's basically just supply chain issues that's left. It's still hard to get batches and it's probably still pretty expensive compared to the 8266?

Re: How to pick a microcontroller

#98

Post by antoniuschan99 »

Eridrus wrote: post #29
antoniuschan99 wrote: post #16

Earlier quoted context omitted.

Light blue bean is $30. ESP is production ready. But doesn't have bluetooth (esp32 is not ready for prime time yet). What are other considerations? Wemos D1 mini or NodeMCU :).

For BLE, but no Wifi, nRF51/52 chips seem like a good fit; bonus is that they're low power,

I'm getting price range of around $30 for these?

Re: How to pick a microcontroller

#99

Post by MrBuddyCasino »

antoniuschan99 wrote: post #97
kirrent wrote: post #73

Earlier quoted context omitted.

I just came back to my esp32 after a 6 week hiatus and the framework has evolved impressively in that amount of time. It's an awesome product for a steal of a price. Definitely at the usable stage.

That's great to hear! If that's the case, then it's basically just supply chain issues that's left. It's still hard to get batches and it's probably still pretty expensive compared to the 8266?

That is true, but the SDK is so much better that frankly I don't care, but then I'm not doing high volume products either so thats easy to say.

Re: How to pick a microcontroller

#100

Post by Eridrus »

antoniuschan99 wrote: post #98
Eridrus wrote: post #29

Earlier quoted context omitted.

For BLE, but no Wifi, nRF51/52 chips seem like a good fit; bonus is that they're low power,

I'm getting price range of around $30 for these?

You're probably looking at dev boards, rather than the single chips, they're in the $2-3 range.
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