STM32 based MySensors boards

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freynder
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Joined: Wed May 30, 2018 2:06 pm

STM32 based MySensors boards

Post by freynder » Mon Jun 25, 2018 2:43 pm

Hi,

I have been using Bluepill boards for creating MySensors (https://www.mysensors.org/) nodes. The Bluepill is a bit large compared to Arduino Mini Pro boards which are commonly used for these projects.

I therefore tried to design a much smaller, very basic board but with all GPIOs exposed. There is no voltage regulator, USB, leds, etc; it is meant to run from 2 AA batteries, sleep most of the time and send sporadic communications to the gateway using an RFM69 communication module.

I'm still rather new at this so there are no guarantees the board is working. I'm waiting for prototype boards to perform testing.

Dimensions are: 36.56mm x 20.32mm (1.4" x 0.8")

Images below:
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More details here: https://github.com/freynder/STM32_Sensor

An earlier attempt with less pins exposed: https://github.com/freynder/STM32_Sensor_V1

edit: added dimensions
Last edited by freynder on Mon Jun 25, 2018 2:59 pm, edited 1 time in total.

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Slammer
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Location: Athens, Greece

Re: STM32 based MySensors boards

Post by Slammer » Mon Jun 25, 2018 2:49 pm

Nice!
How big is the software for MySensors and how many GPIO are required? Maybe you can try even smaller STM32, like STM32F030F4....
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freynder
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Re: STM32 based MySensors boards

Post by freynder » Mon Jun 25, 2018 2:57 pm

I tried to make it general purpose and expose all GPIO's but in most cases (buttons, PIR sensor, temperature measurement) only a few GPIO's are needed. It would make sense to make a smaller one, similar to my first attempt (also linked in original post). My PIR sensor sketch uses 42K flash, I suppose 64K would be a minimum and 128K better.

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Slammer
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Re: STM32 based MySensors boards

Post by Slammer » Mon Jun 25, 2018 9:41 pm

OK! It is big... I thought that 16KB Flash is enough!
Anyway, you can also try something like STM32L431CC, it is almost pin compatible with STM32F103C8 but with much better Ultra Low Power core with FPU, better/newer low powered peripherals, rich analog subsystem for sensor applications (16bit ADC, 2ch DAC, integrated opamp and comparators), and 256KB Flash/64KB Ram. The price difference is small (from distributors). The problem with these chips is that the arduino core is not very mature.
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freynder
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Re: STM32 based MySensors boards

Post by freynder » Tue Jun 26, 2018 12:49 pm

Thank you, I'll review that in detail (and some others) for maybe a next version. Arduino core is crucial however for MySensors.

stevestrong
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Re: STM32 based MySensors boards

Post by stevestrong » Tue Jun 26, 2018 1:44 pm

Which "Arduino" core do you mean? Leaflabs (Roger's) or ST or generic?

freynder
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Re: STM32 based MySensors boards

Post by freynder » Tue Jun 26, 2018 1:47 pm

I've only used Bluepills with Roger's core so far since it worked well. Not sure how well the others work with MySensors.

freynder
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Re: STM32 based MySensors boards

Post by freynder » Sat Aug 11, 2018 2:36 pm

Assembled and performed a few simple tests: upload using stlink, upload using serial (using buttons to select boot mode), running Mysensors SecurityPersonalizer and basic sketch with RFM69 initialization. Everything seems to be working. More extensive tests will be performed later.

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