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Topic: Arduino Shield for programmable DIY bench power supply with SCPI support (Read 14173 times) previous topic - next topic

prasimix

The touch screen really has a central place in this project. Therefore predictable behavior with high level of precision is of paramount importance.

We spent (or wasted) considerable amount of time guessing what going wrong with touch screen control. Possibly we just discover hot water by finding that working with touch screen is not straight forward. Maybe the problem laying in unfortunate match of resistive sensor and touch controller (XPT2046). At the beginning a Utouch library is taken for granted as "the solution" for small displays and comes with Arduino support that we need.
But, after some time my colleague realized that Utouch missed many things and that simply blaming hardware is not fair. Actually it's possible to completely change situation from frustrating and completely unusable to precise and predicable solution. He started with tweaking existing utouch, and finally gave up completely from it and in addition deploy tactics that David Beer presented here (thank you very much David!).
I prepared two short demos, first one with simple filtering and second one with new approach:

https://www.youtube.com/watch?v=_mrBomMLKiI

https://www.youtube.com/watch?v=BP_5paHGkL8


prasimix

All required coding, testing and tweaking required for programming output parameters are finished and I made a short video about that. This first video covers all 3 input modes: Slider, Step and Keypad. The first two also have interactive/non-interactive option that gives us 5 possible input modes. They together represents a solid equivalent for the one (or combination) of standard input devices such as multi-turn potentiometer, incremental encoder or numeric keypad.

As you can see many options are still missing but the biggest obstacle - having usable screen-touch control is resolved. I didn't use stylus during the whole presentation just my finger (that is maturely thick). Now we can continue more comfortably to add everything that is already available over remote console (using SCPI commands) to the local interface and I'll try to cover progress with more videos.
Your comments are highly welcomed.

https://www.youtube.com/watch?v=jofIdGx2gTg

Ton_O

Indeed, solution has been designed thoroughly and complete; my compliments!
Any information on the cost of the total project?
And do you sell parts (notably the PCB's)?

prasimix

Hi Ton_O, the solution is almost completed. Hardware part more then firmware, but we are progressing very well. On hardware side I'd like to test existing solution (let's call it Revision 4) how SMPS pre-regulator based on LTC3864 will works and as you can see in few previous posts idea is to make a whole solution more compact. That will be Revision 5.
Firmware in version M2 (Milestone Two) should offer complete control over local TFT display with touch-screen (what we have now is SCPI remote control, and basic functionality over TFT display/touch-screen as it's shown in latest video).
Cost of the whole solution is not small, BUT if we take into account capability, performance and that is completely open and with advanced control then even in quantity of one it starts to make lots of sense. Total cost can be estimated using BOMs that are available on the GitHub, and for the Revision 4, they can be find on the following links:

Arduino Shield ~77€ (without Arduino board)
Pre-regulator ~36€ (for two)
Post-regulator ~62€ (for two)
AUX Power supply 33€

When we add enclosure (20€ without heatsinks nor customization of front and rear panel) and main transformer (~50€) total without VAT and PCBs is about 280€ (or 300€ with "eBay-grade" Arduino board).

Many people already asked the same question about selling PCBs. That supports my idea to organize group buy for at least PCBs and possibly customized metal enclosure. If you don't want to wait Eagle and Gerber files are also available on the GitHub and if you need three (that is min. quantity for order) or more maybe OSHpark could start to be attractive. You can find even more then what you possibly need here.

Since we are still working on it and everything is open for new suggestions don't hesitate to post your comments, wishes, ideas, etc.

prasimix



Many things was happen with this project it recent months both on hardware and software side. Details could be found on project home page or on the GitHub. In the meantime I was successfully completed an experimental group buy for bare PCBs, TFT display and customized metal enclosure. That encourage me to start thinking about another group buy but this time for assembled modules and all other parts. But PCBA service makes sense only for larger quantity that means more people needs to be involved and I decide to run new group buy as a crowdfunding campaign.

The campaign will be conducted on the CrowdSupply and I'd like to hear your opinions about pledge levels. First please note that I'm not going to offer a completed solution. The reason for that is CE/FCC certification that is very costly and for 100 units that is campaign goal it could make a whole calculation completely unattractive.
Again, this is a group buy, not a new product production kick start, because it's not a profit driven (I have another source of money for living). Therefore prices of all pledges will be set to cover without loss the cost of manufacturing, packaging, transportation and campaign fulfillment cost, crowdfunding platform (12%) and payment gateway fees (2.9% + $0.30).
I was thinking about the following pledge levels (the final number and contents will be set in accordance with interested parties wishes):

  • Set of bare PCBs only (4 of them, 2 layer)
  • As above + metal enclosure (with other metal parts such as TFT display support, AC/DC modules support, channel's heatsinks)
  • Set of assembled PCBs only
  • As above + metal enclosure set + wire harness
  • As above + TFT display + AC/DC modules (2 of them)
  • As above + Arduino Due

The latest one include all what is needed to assembly a fully functional unit that can be ready to run after firmware is uploaded. In essence you'll need a screwdriver for that operation and PC with Arduino IDE for uploading. Of course, you also need multimeter to calibrate it using built-in calibration wizard (see video).

Thanks in advance for your valuable inputs.

prasimix

The group buy from bare PCBs to complete kit is started yesterday. Here is the campaign page.

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