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200sx RS13 "GT3" never ending story.........

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  • #61
    How have I not subbed?
    1990 240sx - Aristo 2JZGTE, R154, GT37, Defsport Wilwood kit, KTS coilovers - daily driver
    1991 civic si - B18C5 / toda / ATS / hytech - autox
    2001 integra type R - Greddy td05-18g - garage queen


    • #62
      First summer in 12-years I haven’t touched my S13. My parents house and garage has been in the market and is finally sold. Since summer I have been helping my stepfather to convert his old barn into garage. New doors, insulation, roof, concrete floor, interior paneling, heating system. Everything was done and week before Nissan was to be transported I got a call that the garage was burn down. Only material losses with the barn and tools.

      Massive setback but plans for new garage are underway. Hopefully construction will start next spring. Summer will be busy again with construction work. Nissan is in cold storage and hibernation until new garage is ready.

      S13 arrived safely to new temporary home.

      Iīll keep on working on my car related electronics and software projects until construction starts.


      • #63
        The side profile pic loves wicked!


        • #64
          I really like your PDM. I've been thinking about making a smaller 6-10 channel pdm myself so I don't have to add a new relay every time I add an efan or other accessory to my car. Why the crazy powerful microcontroller? Why not run something cheaper (less IO, 16-bit or 8-bit) with an external adc? Also, what connectors did you end up with for use on the pdm box?

          Really enjoying your build thread and I can't wait for more!


          • #65
            Originally posted by Stingy49 View Post
            Why the crazy powerful microcontroller? Why not run something cheaper (less IO, 16-bit or 8-bit) with an external adc?
            • The chip I used was about 12 $ and it has everything built in. Powerfull CPU, big analog front end, CAN-bus, USB, I2C, SPI, PWM. I donīt think there is much $ to be saved going 8-bit or 16-bit and separate analog.
            • 32-bit Arm micros is currently the dominating architechture which ensures long product life.
            • For marketing 100Mhz 32-bit Arm processor is more appealing than 16Mhz 8-bit.
            • Built in electrical water and oil pump controller will benefit CPU-speed as it will be doing math.

            Originally posted by Stingy49 View Post
            Also, what connectors did you end up with for use on the pdm box?
            Proper post coming later about the connectors and assembly.


            • #66

              PWM is a square wave that is on&off with certain frequency. Depending on the dutycycle output voltage can be changed. The reason why I wanted to include this to the PDM is the ability to control speed of electric motors directly. Applications can be fuelpump, engine waterpump, gearbox and rear differential oilcooling, interior fan, interior lighting.

              Electric motors are inductive loads. Addition to the inrush current they also induce massive voltage spikes of hundreds volts when turned on/off. And this is something we would do with PWM repeatedly. IC-driver circuit is built to handle this capping the negative voltage spike to -30 V. But with PWM and continues voltage spike bombardment I wanted to make sure the IC-would not be burned out by adding a flyback diode circuit.

              I did some testing with standard automotive relay which is an inductive load. I wanted to see what kind of spikes there really are, how the IC-driver perform and how well the flyback diode would work.

              I connected standard automovtive relay directly to battery and switched the relay off.

              I measured +200 V and -300 V transients lasting 600 ĩs before reaching 0 V.

              Next I connected the relay to my PDM output without the flyback diode circuit. According to datasheet the Driver-IC will cap the negative voltage to -30 V. This proved to be right in my measurement below.

              Next was time to see how the flyback diode circuit performs. Theory is that when the negative voltage appears above the load the D5-diode offers and low impedance route for I_d current.

              Here is the result when the D5 diode was added. The negative voltage spike is nearly completely eliminated.

              For the software I added PWM-option. PWM is available on 9-channels. At the moment pwm is driven form information in the CAN-bus.

              For my test I bought cheap few $ CAN-module from ebay and connected to my Arduino. Arduino reads potentiometer connected to itīs analog input and transmits the value to PDM via CAN-bus. I am driving my heallight for this test.

              Last edited by Logic; 05-12-2018, 09:58 AM.


              • #67
                Firmware Update

                Last piece of the puzzle is to create firmware update functionality. This will enable to fix bugs and bring new options and functionality once the product is out in the world. Not much to see here. Just select the file from HDD and press update. It will rewrite the memory on the PDM with new firmware.

                This brings the project to the point that itīs time for field testing. Every peripheral used in the microcontroller in this project has been programmed and tested. Execpt the connection between two cards that uses UART to communicate. I will do this when I have two PDM cards assebled.

                I have components at home to do one PDM-card but I need two to program the communication between two cards. I looked digikey to order more parts but the IC-driver circuit had zero stock.

                "Version no longer manufactured. Discontinued at Digi-Key"

                Mouser was bit more promising but still grimm looking.

                "Manufacturing delays have been reported on this product. This may be due to unexpected demand, production difficulties or raw material issues."

                The IC-driver is still listed active on the manufacturer website. I will contact them and ask if this is just a temporary thing. If not I will change to another IC-driver. That will require PCB redesign. I was gonna order new PCB:s any way because the first batch has things to be fixed and improved.

                So next step is go get new pcb:s made and assembly the final product. Field testing will be done in my dailydriver Citroen. Iīll have it run the healights and maeby radiator fan and stereos. Something I can easily connect and put back when im done.

                Im also starting on V2 of the software with new page system.
                Last edited by Logic; 04-29-2018, 03:28 PM.