New RPi Zero W - with Wifi and Bluetooth

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RogerClark
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Re: New RPi Zero W - with Wifi and Bluetooth

Postby RogerClark » Wed Mar 01, 2017 8:12 pm

I have only used my RPi(s) as small linux boxes rather than for the sort if thing I would use a MCU for.

I have the original RPi Zero, but you have to connect it to a USB hub and use external Wifi etc, and it also needs an adaptor to plug into a HDMI monitor.

I dont see the RPi Zero replacing the Arduino MCU for small projects, e.g. over the years I have use Arduinos to fix my automatic garage door opener, build a new charge controller for my electric drill, build a new thermocouple interface to my (useless / cheap / chinese) reflow oven, build multiple Open Power Meter systems, build systems to control those 433mhz mains socket switches etc etc etc

IMHO using a MCU is a better solution for many things, and something like a RPi only if you need a lot of processing power or a lot of RAM , or both etc.

And over time things seem to be converging, with the MCUs getting faster and more Flash and RAM and the Linux boards getting cheaper and gaining GPIO capabilities

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leavesw
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Re: New RPi Zero W - with Wifi and Bluetooth

Postby leavesw » Wed Mar 01, 2017 8:32 pm

RogerClark wrote:I have only used my RPi(s) as small linux boxes rather than for the sort if thing I would use a MCU for.

I have the original RPi Zero, but you have to connect it to a USB hub and use external Wifi etc, and it also needs an adaptor to plug into a HDMI monitor.

I dont see the RPi Zero replacing the Arduino MCU for small projects, e.g. over the years I have use Arduinos to fix my automatic garage door opener, build a new charge controller for my electric drill, build a new thermocouple interface to my (useless / cheap / chinese) reflow oven, build multiple Open Power Meter systems, build systems to control those 433mhz mains socket switches etc etc etc

IMHO using a MCU is a better solution for many things, and something like a RPi only if you need a lot of processing power or a lot of RAM , or both etc.

And over time things seem to be converging, with the MCUs getting faster and more Flash and RAM and the Linux boards getting cheaper and gaining GPIO capabilities


I have to say I cannot agree with you more.

The other thing RPi does not provide is ADCs while most MCU has that. Moreover, you cannot really use it for low-power applications :)
You need at least 1A rating power source to make sure that SD card gets enough power so that the filesystem will not be destroyed by IO errors (which happened on Rpi3 a lot if you only use your USB port).

I have worked on FPGAs before, and the lessons that I learned from that experience is that one really needs to chose a technology that fits the application - if it can be achieved by a MCU, you do not want to waste your time and energy with those fancy devices :)
Moreover, a MCU with Bluetooth stack might be much easier to use than Bluetooth stack and library in Linux, if that is the only thing you want to do :)

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RogerClark
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Re: New RPi Zero W - with Wifi and Bluetooth

Postby RogerClark » Wed Mar 01, 2017 8:49 pm

Mutual agreement here...

I find the Nordic nRF5 series of Bluetooth MCUs the best approach if you need BLE. They are amazingly low power, and now have a powerful 64Mhz cortex M4F processor, and have ADC PWM and even a separate sub section they call PPI which can handle simple sub tasks related GPIO.

BTW. We forgot to mention readback security being excellent on MCUs in general.

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leavesw
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Re: New RPi Zero W - with Wifi and Bluetooth

Postby leavesw » Wed Mar 01, 2017 9:29 pm

Yes - Nordic nRF5 are great BLE MCUs -
I tear up an estimote sticker months ago - they use Nordic nRF5 series as well with external accelerometers.
They claim 2-5 years of battery life with CR2477 coin batteries (1000mAh)

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Squonk42
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Re: New RPi Zero W - with Wifi and Bluetooth

Postby Squonk42 » Wed Mar 01, 2017 10:35 pm

Just consider the only language universally available on all computers and smartphone (Javascript) and the related number of potential developers with experience in it: you may call them script monkeys and not consider these Javascript developers as "real" programmers, but nowadays they outnumber by orders of magnitude the number of core C developers.

You may consider that using a Node.js server on a Linux-based distro for blinking a LED is like firing a bazooka to kill a fly compared to plain old bare-metal C firmware.

But remember when Arduino was introduced, or C++, or even plain C... Newer tools, same debate.

These developers are the RPi audience.

RPi is certainly not the most cost, energy or size effective computer, but it is by far the easiest to master for this new generation of programmers.

Not a problem if it drives more people into real embedded programming.

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BennehBoy
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Re: New RPi Zero W - with Wifi and Bluetooth

Postby BennehBoy » Wed Mar 01, 2017 10:45 pm

Squonk42 wrote:Not a problem if it drives more people into real embedded programming.


Anything that stimulates creativity is good imho.
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RogerClark
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Re: New RPi Zero W - with Wifi and Bluetooth

Postby RogerClark » Wed Mar 01, 2017 11:50 pm

I think the PRi is great. I 3 of them, and will have 4 when the Zero W arrives.

But its just not the optimal device for my projects

Re: nRF52

Depends on how often the device advertises and whether it does anything else

I have the Nordic Power Profiler Kit, and analysed the power consumption on a project I'm working on, and I think I'll get 18 months battery life with my current config, as it advertises once per second and measures its sensors and battery voltage etc ever 15 secs

I need to optimise the code as I only really need to read the ADC for the battery every hour not on the same ISR as the other sensors, but in the long term I also need to read some accelerometers and the lowest refresh rate I can use is for the processor to wake every 3.2 secs to read the accelerometer FIFO of samples

Nordic are IMHO the best provider of BLE solutions for small developers, as they provide GCC makefiles for all their examples, (as well as Keil and IAR)

They have a github account where they post lots of source code, they also have an excellent developer forum and staff to monitor and answer questions, as well as relying on community support.

They also have a private online support system and will even review your hardware design, and apparently (not tried this myself), they will critique your hardware if you send it to them.

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BennehBoy
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Re: New RPi Zero W - with Wifi and Bluetooth

Postby BennehBoy » Thu Mar 02, 2017 7:40 am

Nordic sound as though they really know how to grow a community.
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ag123
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Re: New RPi Zero W - with Wifi and Bluetooth

Postby ag123 » Sun Mar 05, 2017 9:17 am

these may displace those cortex-m BLE and/or wifi integrated MCU (e.g. nrf51822) with low resources
the trouble with integrated MCUs is the very small amount of ram available, though flash seem quite accomodating
it severely limits what's possible e.g. to make a smart watch 16k sram & 128k flash and one wants to drive an lcd, drive the bluetooth & wifi stack & do all the fancy apps (e.g. pedometer etc), 1'd run out of options pretty quickly before it is even possible

i'm thinking there is a 'convergence point' where cortex-m start to ship in bigger ram and flash sizes which cortex-a with beefy ram and flash tries to reduce the physical footprint and in addition to all that add that 2.4ghz radio for bluetooth & wifi
this seemed to be getting a lot of momentum i.e. mcu + bluetooth or/and wifi in an integrated all-in-one soc

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RogerClark
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Re: New RPi Zero W - with Wifi and Bluetooth

Postby RogerClark » Sun Mar 05, 2017 9:49 am

I think the ESP8266 (ESP-12) modules have taken a lot of the market share of traditional MCU projects.
Going well beyond just people wanting Wifi, as they have loads of Flash and RAM and a relatively fast processor, and are cheap.

Looking at the AliExpress listings, I think tens of thousands of them have been sold.

They are however very power hungry, which may or may not be an issue.

The ESP32 may take over from the ESP8266 when the prices come down and there is greater availability and the Arduino core stabilises.

The Nordic devices still seem very niche. I'm not sure why that is. Possibly just because no one in China brought out a simple to use module e.g. Blue Pill format using them. Price is also not as competitive as the ESP8266 or STM32, which seems mainly because companies (even in China) are trying to get the maximum price they can for them, probably as a premium product.


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