Category: Embedded Development

PLC – Connectivity Module

Still an early draft, but show the 8 RS-485 connectors at top/bottom. I only use right angle headers in the 3D, but they are 2.54 pich so they can be replaced with other connectors. I still have a few loose ends. RS485 circuit can be switched off into 3-state by setting RE High and DE…

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PLC – Connectors Top/Bottom

This new Connectivity Module have 8 x RS485 connectors. I use the front for the antenna and USB, while top/bottom for connectors that most likely will be permanently wired. Some users would probably request both 4-wire RS422 and RS232 and I will make a board for those later. I also need a CAN board. As…

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PLC System

  One of the challenges I have is the size of connectors in front of the modules. I am actually considering using Top and Bottom on the modules to increase connector space. Another issue is that the screw connectors used on the RS485 board below is not really operational from front alone. Looking at the…

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RS485 Circuits

This is a classic RS485 circuit that I realize is not that good. It works fine, but it requires that ground always is included because of the 12V diodes. This simplified circuit is in many ways better as we actually can use a twisted pair only. This shows a none-isolated RS-X port. I also drag…

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PLC-Connectivity Module

This draft will give me 6 (8) RS-X ports. 6 if I use the backbone and 8 if I use this stand-alone. In addition Ethernet, Wifi and Bluetooth as well as USB. RS-X Port is 4 pins with 12V and RS485 differential signalling. Basically it feeds 12V Power to the RS-X devices. I like playing…

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PLC – Connectivity Module

I drafted a GSM/Ethernet module as well as a 3xGalvanic RS485 earlier, but I am toying with the idea of attempting a PLC Module with STM32F405 using ESP32 for Ethernet/Wifi and 4-6 RS-X ports. 4 if used as PLC-module, 6 if used stand-alone. I have also 2 CAN ports if I can find space/pins for…

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Plain VM – RTOS

I need a few C/C++ components to implement the Plain VM, one of them is a RTOS . I wrote my own RTOS that runs on both Arduino, ESP32, STM32, Windows and Linux years ago. It is a simple linear scheduler.  I found it quite handy even on Windows applications as it scale better and…

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Plain – Parsing VM Instructions

One concern as I implement the VM is the parsing performance on instructions. The Data Descriptor below illustrate the challenge. It is a dynamic structure with bit fields. For every bit field I end up decoding it causing AND /ROTATE instructions. It is bit packed to save space, but decoding a bit-packed field will cost…

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SG90 9G Servo is no wimp

This litle Servo about 3 x 3cm is far from a wimp as far at current usage goes. A single Servo have no problem dragging a 10A PSU down – actually I think it’s the current regulation that is predictive, meaning it drops out because current raise is to fast – but, anyway – the…

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