BasicPI

HMI Designer & Browser

Posted on by Jan

This is an early beta of the HMI Designer. The idea is that you draw your HMI displays, save them as XML and then send them to a HMI Browser. The Browser will execute the graphics and send back user events allowing a system with no knowledge of HMI, how or what to make use of advanced HMI capabilities.

More important is that it will support Windows, Linux, iOS, Android and customized embedded solutions without the programmer needing to dig into specialized HMI design skillsets.

HMI Broweser is not so unlike a Web Browser, but it is designed to be a HMI for an embedded solution and contains pre-made graphics components and infrastructure dedicated for complex SCADA systems.

All code done in C/C++ with Qt as base.

Model Train System

Posted on by Jan

This was my first project that got me started on electronics again. The initial design did not work at all. It used an STM32 on one side and ESP-03 on the other which created too much interference + I had selected the wrong type H-Drive. The MCU and PSU design did however work well and was re-used on the second design based on ESP32. This one failed on a detail in the datasheet I had overlooked – not all IO pins are output. The main PCB is pictured below.

 


The backside is a bit special since it will only hold a single component ESP32. This is basically just a ESP32 with a PSU and a H-Bridge. I have drafted a New Controller, but it holding back a little investigating the position system that would change this from being a Remote IO toy to be an automated Train system.

This is the intended utility driver to enable control of other things. It was on this I discovered the IO mistake as I only have 8 and not 12 servo ports here. To move on I actually plan to use my new modular control system because it is so much more flexible. But, I will probably still maintain these small all-in one controllers based on ESP32. This worked excellent expect for the surprise on on 4 of the ports.

The main challenge on this project was however that I failed to find a position system that would work. The initial attempt was to triangulate on ultra-sound and yes it works, but it’s no way to get required components into a small model train cockpit. The second attempt was to triangulate on radio strength for Wifi and Bluetooth. And again – yes it kind of works, but it is far to inaccurate.

The third method was suggested by a friend and might just work. He suggested using a camera in the ceiling and recognize model train positions that way. I figured that if I use a IR led to send info I can identify train and position.

Changing the layout of the control system is easy, but I also needed to add a programmer. The intention is that these control systems will be programmed through Wifi, but we need a method to download the bootloader the first time.

I plan using OpenCV on a Raspberry PI with Camera for image processing, but this is an area where I am on thin ice. I know this should work, but I have little experience with image processing so this will be a new.

 

HMI Block Diagram

Posted on by Jan

This diagram illustrate the HMI solution the way I am planning it. I would like one external RS485/UART so I can attach the display to any embedded solution. CAN, USB and SPI Backbone is mandatory. And I think SPI Half Duplex will do fine over max ca 50cm that we talk about here. SPI is also straight forward as it basically only will be a small 50 cent MCU on the add-on modules. I could even use full SPI in this case as we always will be talking to the main MCU and CS pins would solve the issue with knowing what module that I communicate with since these cheaper MCU’s don’t have an id number.

 

HMI Solution

Posted on by Jan

I want to work on creating a modular HMI solution. I already have Raspberry PI with HDMI, Keyboard and Mouse interface, but I need a solution for smaller displays, specialized button’s and knobs to go on instrument type projects. The concept I like is that an embedded device can store it’s own interface and then send that to a HMI unit that operate the display part as an intelligent IO. This means that the HMI itself behave more like an HMI Browser drawing graphics according to a spec while the embedded device receive events like “Button OK Pushed” dealing with the actual user input.

Several solutions that uses this scheme exist, so this is not a new invention. But, I want to put it into a system where I can add HMI components on modular bases.

The 2 displays above are my first targets. The larger 4″ display have 800×480 pixel resolution and a 2×17 pin connector using OTM8009A as driver. The interface is either SPI or parallell and it exist sample code for STM32 on this. The smaller display is 1.3″ and 240×240 pixels using SPI interface. These 2 displays caught my attention because of their design with screw holes, bare-bone adapter, high resolution and low cost. Each driver will require a lot of code + I need specialized cables so I will select a range of displays I like and stick to them.

The next part of the project is buttons and knobs. Basically a system to build a customized HMI using modular components. My first thought here is to use the smaller STM32F030F4 or F042F6 on Half Duplex SPI or RS485. I could create a back-plane with PCB screw holes in array formation allowing smaller modules to be added and cabled up. One module can be the display while the rest is knobs and arrays around it as needed. I have to work on the mechanical solution here to avoid that screw holes occupy to much space making this impractical to use.

The big win by doing this is that customized HMI solutions basically is to expensive for low volume products/projects “as is”. So, by making a modular system we should be able to assemble our own customized HMI based on components that are low cost due to volumes even if our project is an one off.

So, to sum this up I am actually talking about several PCB’s:

  • A Hat with cables/interface to displays. I will try to make it possible to mount displays directly, but I don’t thing it will be very practical – so I assume a cable between the Hat and display as a minimum and then a network attaching add-on HMI modules.
  • Rotary knob module.
  • Button arrays
  • Led’s.
  • A backpane plane to plug Things into.

LoRa+GPS Hat

Posted on by Jan

This is one of my more exiting projects as I add a LoRa transmitter and GPS to a Hat. E22-900M30S support 12km range while the smaller E22900M22S support ca 6km Range. I have received units and PCB so just waiting for a time-slot to work on this Hat.

  • Raspberry PI Hat format
  • 42Mbps SPI backbone bus
  • CAN Bus
  • LoRa 868 or 433 Mhz
  • GPS
  • USB
  • TTL UART

CAN Adapter

Posted on by Jan

Many of my newer devices have CAN so I wanted a simple USB(CAN adapter. It is nothing special with this project. I used a STM32F105 with USB on one side and CAN on the other. A minimalistic UDB-CAN Adapter just6 to avoid the need to pay a fortune for these.

The first rev 1.0 missed an external x-tal that turned out to be a mistake as USB required this. Once this was added on rev 1.1 the adapter worked.

It should be noted that XPortHub have both USB, 2 x CAN, 2xRS485, 2xRS232 and more so it’s questionable if I continue this Project.

 

60V 50A 3-Phase Driver

Posted on by Jan

This is a specialized 3-phase driver that uses DRV8301. It is more narrow than the 4 channel design and not so complicated to build. I did this design before I did the larger 4 channel design so it is several things on this design I improved on the 4 channel design.

  • Temperature sensors are still external on this one.
  • No smart way of adding capacitors on Power In.

The intention with the 3mm air wires on the back was to have heat-sink on the top. I later realized that I will be better off using a heat-sink on the PCB on the back, but that is an assembly change. I can also shorten this by 1cm by removing the air wires at right and take the output directly from between the MOSFET’s.

The total size of this is 25mm x 100mm and I have a heat-sink for this, so it’s an awesome design. It will sustain ca 50A, but can go higher for a short moment. This design is also very close to the Vedder ESC design so we can borrow that source code with minor modifications.

The one change I am considering is the temperature sensor(s). I seriously would like them on the PCB, so lets see. I have not ordered PCB for this yet because I am considering a few changes + I want to build the 4-channel design first.

Comparing this with the more universal 4 channel I must admit that this has one advantage – size.

60V 50A Motor Driver

Posted on by Jan

This is an awesome design allowing 60V @50A on 4 separate Half H-bridges. The design is a step up from the 30V/20A design using more powerfully MOSFET’s and adding wiring to support higher currents. It is also a Hat design, meaning I can add Hat’s to extend the controller. The pic above show my specialized motor controller PCB’s with this one at right.

I face some practical challenges testing this. Some of you might recall that I had challenges with 20A – I simply had no PSU that could support it. Or well – I actually do now. I do have a 60V/20 PSU and plan to build 2 of these.

My main concern and maybe biggest mistake is however the design of the air wires. I have 2mm wires, but lack the 3mm and realize that the way I have designed the 3mm makes them very difficult to create and solder on. This is a design with components on a single side intended to make it optional for production, but those wires require a lot of manual work defeating the object.

What I lack on this is a galvanic isolated communication interface. I attempted one earlier, and it worked, but heat dissipation was larger than I wanted. So what I will do is to create a separate Hat for this purpose later.

I should also point out that I might separate this board into 2 boards. One Driver and One controller. The interface between the MCU and MOSFET driver is more or less standard and I could need a galvanic interface here as well which would be easier to add if I separated the boards + it would allow me to add even more powerfully drivers.

The 4 separate channels means I can drive 4 solenoids, 2 DC motors, a 3-phase motor, a stepper motor or any combination. It is 4 x High side current sensors, hall sensors, CAN interface and USB. MCU can be powered by USB to keep it separate.