This means you can use all available pins and access and extend with: CAN, UARTs, etc. Possible to add custom electronics: For reusing this motor controller on different devices, you can extend the electrocnis with a custom header on top of the Bluepill. Meaning you should have no problems with part availability, and if you do, you will be able to change most parts with equivalents depending on availability or prefrence, without need to change the pcb layout. Uses popular components / footprints / pinouts. Popular components: Uses the popular Bluepill STM32F103 board, meaning it is easy to develop firmware for it. Main objectives:Įasy to build and repair DIY: It uses DC-DC modules, a development board instead of an uC chip, SMD passive components are all 0805 or bigger, and ICs are SOIC8 or SOIC14. The target for this EV motor controller is to power small EVs like EBikes or EScooters like Xiaomi M365, and offer better customizability and repairability. So measure the capacitance of the wire pair and that will directly relate to the bit rate it will support with a particular driver.Note: 'main' branch is under development, there is a change to use KiCad as compared to v0.5.2 (current HEAD of feature/v0_5_2, i.e. Speeds were increased when driver devices could switch faster and supply more current. Same applies to any serial communication over wires. This took time, making the signal not a square wave, but one with sloping sides. By using wire with thicker insulation and lower twist of the pair, you could get 100 ft because the capacitance was lower.Īll this difference is because the signal was polar, reversing from + to - and the line drivers had to reverse the charge on the wire pair. Back when RS-232 was king, 50ft was the limit for 9600bps. The limiting factor is the capacitance of the wiring. Twisted pairs minimise interference, they reduce the interference given out by one circuit, they minimise the interference picked up by an adjacent circuit and they minimise the interference picked up from the environment. Unfortunately I cannot put actual numbers to it, but maybe someone else can. I hope someone can share his/her experience on this. other components like voltage regulators or any capacitors which might somehow interfere or the track width and spacing on the board itself. Can the pcb layout influence the communication? E.g.Is the daisy-chain like setup with all its different connectors somehow harmful for the communication performance? I plan to add up to 15 slaves.What influence does the cable type really have when it is only a distance of 10-20meters? Is there really already a need for twisted calbes or even shielding?.Of course there are some other components (3) on the board (voltage regulator with capacitors, some transistors for triggering other devices, some resistors etc.). Screenshot_Schematic_Communication_Chain 669×870 67.3 KBįor cables (1) I use simple 4-Pole parallel calbles because those worked on the first try as well, JST-XH connectors on the boards (2) for the serial chain. The complete system then somewhat looks like this: The master seems to be unable to recieve all the serial bytes or none at all. However the final pcb does work with shorter cables so the circuit should be allright but not with nearly as long cables as the setup with the external modules. I used this schematic for the rs485 module and added all the neccessary components to my pcb. To save some space and setup time in my later application I designed a pcb with the module included. I could even communicate through a long parallel (non-twisted) cable consisting of multiple extention parts which should be the absolute worst case. I noticed pretty quickly that the rs485 is the much safer method for longer cable lengths than the native ttl.įor the start I used additional modules and was following this tutorial which worked perfectly: Please see my introduction and a set of questions below. I am setting up a series of serial slaves which shall communicate with an arduino or RPi master via RS485 and I am having some trouble finding out the suitable cable-converter-connector combination for ideal communication.
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