First off: The tinyK20 project is progressing fine and is now on Hackaday.io :-).
For a research project we would like to use the tinyK20 to log gyro sensor data. For this I have created a quick-n-dirty project to explore how feasible it is. The tinyK20 has all the pins on the outside of the board, so I’m able to put it on a bread board:
tinyK20 on Breadboard
The tinyK20 has been designed with the data logger as one of its applications. For this, there is a micro-SD card socket on the bottom side of the PCB:
Micro SD Card Socket on TinyK20
The cool thing with the tinyK20 is that I can use it to debug another board. As a bonus, the tinyK20 is able to power the target board trough the SWD cable:
💡 The internal USB regulator of the Freescale Kinetis K20 is able to offer around 100 mA. I use the DC-DC converter on the backside of the tinyK20 to power more than the 100 mA.
tinyK20 debugging another tinyK20
I used a Segger J-Link to get performance data with the Segger SystemViewer.
Debugging with J-Link
Right now I’m logging dummy data. Checking the performance with the Segger SystemViewer for FreeRTOS shows around 20 ms to append 20 bytes to a file (csv format):
tinyK20 Data Logger with Segger SystemViewer
So far, I have plenty of power to do that data logger application, and I even have a shell with USB and the Segger RTT running :-).
If you want to have a look at that data logger project, it is on GitHub: https://github.com/ErichStyger/mcuoneclipse/tree/master/Examples/KDS/tinyK20/tinyK20_DataLogger
Happy Logging 🙂
Links
- tinyK20 project on Hackaday.io: https://hackaday.io/project/8525-tinyk20-small-uc-board-and-debugger
- tinyK20 articles: https://mcuoneclipse.com/category/boards/tinyk20/
- tinyK20 Data Logger project: https://github.com/ErichStyger/mcuoneclipse/tree/master/Examples/KDS/tinyK20/tinyK20_DataLogger
- Segger SystemViewer: Segger SystemView: Realtime Analysis and Visualization for FreeRTOS
MCU on Eclipse 
Looks great!
The PDF of the schematics on github does not match the Eagle file, the PDF appears to be a later version. Is github up to date, if so which is the latest version?
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Yes, the files on GitHub are not the leatest ones. Need to clean them up and update, probably will find time next week (I hope).
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Hi Erich, any updates on the tinyK20 files, yet?
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Yes, its ultimate , micro-SD card socket on the bottom side of the PCB and cool thing with the tinyK20 is that I can use it to debug another board , that was good thing.
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You’ve done a great job! This is much more flexible than the teensy. Where can I shop for the tinyK20? Does your PCB manufacturer also offer a BTO service for the assembled board?
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Thanks :-). We were thinking about providing some of the boards for sale. It is a matter of demand and efforts. So right now there is no shop for it, but certainly could be considered.
Our PCB manufacturer has not offered BTO service. Do you have a recommendation of a manufacturer doing this?
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No, not really 😦
But what is about http://www.embedded-projects.net/ they offer such a service as far as I know. Or they can be persuaded to pick up your design into their shop?
Or https://www.beta-layout.com. What is about RS-Components or Farnell didn’t they assist developers to bring their ideas to the market?
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What about a Kickstarter project for this, Erich? Then you’d know the quantities up front. Just set your funding limit according to the number of boards you can sell.
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Hi Dave,
that board is something we did internally, with very minimal effort. Doing a Kickstarter project is by far something more time consuming. Plus I think the usual Kickstarter fee is 15-20% too. I have shipped some boards to the ones who have contacted me directly. I’ll be at the NXP FTF Technology Forum in Austin in May this year, so I could carry a few boards with me if there is any interest.
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Yes, a KS is a bit of work, but if you’re careful with your calculations, you should be able to minimize risk (to losing money from your own pockets) 🙂 In large enough quantities, the tinyK20 could end up being pretty reasonably priced! Well, hopefully you’ll change your mind, or maybe someone else will run the KS for your design! I really like it and might have to order a batch from OSHpark to try it out.
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Erich, I’d like to try out the tinyK20. Can you please name your price and payment preference, and I’ll be in touch with quantities? Thanks!!!
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Hi Dave,
you can contact me with the email address noted on https://mcuoneclipse.com/about/
Erich
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Hi Erich,
It looks like you have the MCU-VREGOUT shorted to the output of the output of the external 3.3V Vreg via R4 in your pictures, is that deliberate?
Cheers
Jim
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Yes. R4 is a 0 Ohm resistor you could remove if you would like to cut that line e.g. for energy reduction and running from batteries.
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Hi Erich, I think that topology is risky, unless the regulators are perfectly matched current will flow between them.
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Hi Jim,
yes, that’s why you can remove that resistor.
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