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  • Author Author: camuyano
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Conference Badge with a STM32F0

camuyano

I few years ago i met a group of guys that organized BSides Puerto Rico. For who do not know what BSides is, it is a security conference organized by the community. They happen all around the world so there might be one near you and you do not even know.

Anyhow, for this conference we wanted to make an electronic badge. Last year I went with an Arduino compatible badge by using an Atmega328p. This year though I wanted to use an ARM Cortext micro controller. Based on popularity, prices and accessibility I went with an STM32F0.

What I have in the design is a CH340G a  STM32F030F4P6STM32F030F4P6 two shift registers and a 8 x 8 led matrix

Here is a picture of my first prototype:

All dirty that you see on the board is me and my iron overheating the board. The board has a microUsb connector on the back side and a male usb connector in from (not connected here) beneath the 8Mhz crystal.image

 

The schematic is:

image

All my designs are open at my github

https://github.com/soynerdito/BSides20016Badge/tree/master/BADGE_LED_MATRIX_STM

 

I plan on making a few changes to the board and make a second prototype.

I have two sort of problems with this board.

  1. The micro usb connector has been a pain to solder. All my soldering is by hand and my success rate with the micro usb is not even at 50%. I keep on practicing but it is a pain. Any pointers are welcome.
  2. On my design I wanted to use a 3.3V voltage regulator. However when I mounted the board if I soldered the 3.3V regulator the board didn't worked. So I mounted a 5V regulator and it works. If anyone knows why something like that can happen please comment.
  3. Haven't been able to run with the debugger, all programming done via the factory bootloader.

 

Plans:

  1. Add an EEPROM to add some storage.
  2. Test some sensors and try to incorporate

 

The STM32 seems to be a great MCU but not too easy to start for beginners. I hope people can use them when we give them out.

  • in reply to clem57

    There were a lot of factors I considered.

    To list the most important in order will be like this:

    1. Price
    2. Easy buy (everyone carry them)
    3. Cross platform development options
    4. Popularity (it is used all around)
    5. F0 family is low power and compact size, also can solder by hand
      1. I have the option to use it with battery (maybe I do not, but the option is there)

     

    A while back I joined here an element14 contest where we used a Cypress PSOC4 and I loved. I wanted my new badge to be ARM Cortex. Last year I went with what I knew that will work and it did. But now I wanted more, more speed and ARM.

     

    This is the first time I'm using a STM32. I ordered the cheapest STM32 evaluation board and downloaded a blink led example. Next I designed this board and order it and it worked. My little experience with this chip has been very good. And there are a lot of variations of related chips, so I can grow with them for future boards.

    I really wanted to use a PSOC4 to in some way "pay back" the opportunity they gave me with the challenge, but it will have to be in a different project. I am trying to choose the best option for the particular project and pass on that to the group. No need to always use X micro controller.

    If this project goes as it seems I will be able to make about 250 boards similar to this one with a very modest budget.

  • Nice work. What lead you to using STM32 processors?

    Clem