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  1. L

    Wierd Analog to Digital Problem with MK20DX256VLH7

    Thanks for the reply. I'm having doubts it's the software being the culprit. I have two boards each connected via USB on a different Mac. One of the two boards consistently had this 255 count jump with one of the A2D channels, but the other did not. So, this morning I swapped the two boards...
  2. L

    Wierd Analog to Digital Problem with MK20DX256VLH7

    I have the analog section set to 10 bits, but something strange is happening that I can't explain. I have an analog input that I set to give an output via USB to approximately 2048. Now there is some noise at the input, so the output dithers about ±5 counts. However, after running for a...
  3. L

    Issue with Teensy LC + Pot 10k for Steering Wheel

    It almost sounds to me that your wheel is too sensitive. On a real car there shouldn't be a dead zone in the wheel (unless it's a 1960s Chevy), so I think that the wheel is too sensitive. In aviation they call this PIO (Pilot Induced Oscillations) because each time you try to correct the car...
  4. L

    Using the MKL04 bootloader chip in DIY circuit to program MK20DX256VLH7 (Teensy 3.2)

    I think there is a security bit that can be programed in the MK20DX256VLH7 to prevent that. If you don't need USB, why are you using the boot loader chip, which requires USB? I think the register location is 0x0000040C, but the boot loader chip is hard coded to prevent you from writing to that...
  5. L

    Using the MKL04 bootloader chip in DIY circuit to program MK20DX256VLH7 (Teensy 3.2)

    I would say your "proof-of-concept" is pretty well accepted. Now a clean implementation would be my next phase. Keep in mind that the Teensy 3.2 schematic is a working design that Paul has skillfully, if not masterfully, created. Following that schematic and its layout criteria will do you no...
  6. L

    Using the MKL04 bootloader chip in DIY circuit to program MK20DX256VLH7 (Teensy 3.2)

    Yes, it sounds like a "layout" issue. As I said, the crystal is probably the most sensitive component on the board. Start there (once you get it running again). If you look at various successful layouts, the crystal is always tucked in close to the processor with short traces. By-pass...
  7. L

    Using the MKL04 bootloader chip in DIY circuit to program MK20DX256VLH7 (Teensy 3.2)

    Yes! I hadn't considered the sockets and a picture would be helpful.
  8. L

    Using the MKL04 bootloader chip in DIY circuit to program MK20DX256VLH7 (Teensy 3.2)

    I can't see anything wrong with the schematic, but that doesn't mean the implementation is correct. I would "buzz" out the board very carefully to make sure every connection goes where it is intended and not where it isn't supposed to go. When wringing out a new design it is best to not assume...
  9. L

    How do I "bake" a file into the firmware

    You can put the table in an "include" file and do a #include. Use: static rom name_of_your_table [] = {,,,} You should double check the word rom. I think the compiler should know what it means. When you compile it will be picked up and added to the flash.
  10. L

    How do I correct an analog axis bouncing?

    The software is used in different configurations, depending on how it is implemented and the total number of channels can vary. When I first did this I wanted to create something that would contain the largest number of A/D channels needed, then I would zero out unused channels. I know there...
  11. L

    How do I correct an analog axis bouncing?

    Yes. Keep struggling with the problem. You will get it! The algorithm is simply an algebraic average. That is, you take a number of samples, say 8, and write the down on a piece of paper. Now add up all 8 samples. Next divide the results by the total number of samples, which is 8. The...
  12. L

    Signal Problem; game controller with Teensy3.2 and Tekscan Flexiforce Sensor

    I think you will be better off in the long run with the quality.
  13. L

    Signal Problem; game controller with Teensy3.2 and Tekscan Flexiforce Sensor

    You are apexing your turns too early. :) I would sort out a few things first. 1. Do you know what the no-load resistance of the sensor is? 2. What is the resistance of the sensor at maximum load? 3. What is the A/D input voltage range for the micro board? 4. Is the resistor you are using...
  14. L

    Teensy 4: Global vs local variables speed of execution

    Best to read the manufacture's data sheet on the A/D operation or ask tech support.
  15. L

    Signal Problem; game controller with Teensy3.2 and Tekscan Flexiforce Sensor

    Well, I am thinking you must have created some sort of system schematic for your device. From the picture it looks like the way it is connected is not right. That assumes that the Arduino board's A/D input runs from 0 to 3.3VDC and the analog reference pin is at 3.3VDC.
  16. L

    Signal Problem; game controller with Teensy3.2 and Tekscan Flexiforce Sensor

    I saw flexiforce and assumed it was a flex sensor... The specs on device that aren't great, it has high hysteresis, I wouldn't expect miracles as it appears to be some sort of squashable resistance material, rather than a strain-gauge. The way to check if its the sensor or not is use a...
  17. L

    Signal Problem; game controller with Teensy3.2 and Tekscan Flexiforce Sensor

    If it were me, the first thing I would want to do is prove that it is real and not some artifact of the system. I would need to see the complete schematic, but the way it is wired to the Arduino would not be my first choice. You are creating a voltage divider, but the range is from some point...
  18. L

    Teensy 4: Global vs local variables speed of execution

    More likely it is the sample and hold circuit inside the A/D.
  19. L

    Signal Problem; game controller with Teensy3.2 and Tekscan Flexiforce Sensor

    Happy to help any way I can. The foil pressure sensors, I have found, have issues compared to a true load sensor. I went the route you did thinking I was saving money, but the results were unacceptable. I would first look for affordable COTS load cells (real load cells) and go from there...
  20. L

    Teensy 4: Global vs local variables speed of execution

    Read this applications note on oversampling. It will tell you how to calculate the number of samples required to get X bits of increased resolution. You need a lot of samples, which may render what you want to achieve as not doable, but you should be able to answer that after reading it...
  21. L

    Teensy 4: Global vs local variables speed of execution

    Are you talking about performing oversampling and averaging as a means to improve resolution (i.e., improving SNR of white noise)?
  22. L

    Teensy 4: Global vs local variables speed of execution

    Why not try using a sliding window averaging scheme? The advantage is that you get new results or new data with every completed analog conversion, but it is simply averaged with the previous raw analog data. You can make as many averages as you want. I use 16 because I can simply right shift...
  23. L

    Signal Problem; game controller with Teensy3.2 and Tekscan Flexiforce Sensor

    Wow, that is impressive! I think what you are doing is very clever, indeed. I have a lot of experience in controls much like that. It's what I do. Personally, I am not that much of a fan of these pressure sensitive foils. I would rather use strain gauges, and I do, for applications that...
  24. L

    How do I remove the Flight Sim C and serial debug USB data from the Joystick program?

    I don't need the USB debug serial port data and I don't need the X-Plan Flightsim USB data. So how do I remove them from the code? Teensyduino Tools menu only has USB Type: --> Serial + Keyboard + Mouse + Joystick or USB Type --> Flight Sim Controls + Joystick. I just need the Joystick...
  25. L

    How do I correct an analog axis bouncing?

    I use a sliding window averaging scheme for my game controller. Each pass of the main loop I grab an A/D sample and stuff it into an array that is 16 words deep. I use a counter (Analog_Cnt) that is incremented with each pass to determine where in the array to to stuff it (the array index)...
  26. L

    Signal Problem; game controller with Teensy3.2 and Tekscan Flexiforce Sensor

    I have worked with some of Tekscan products before. Looking at your graph, the vertical axis is the change in A/D value (0 to 1023)? What is the horizontal axis? I am guessing it is not force. Is it time? It would be more useful if the horizontal axis was force, but I don't know how you...
  27. L

    Teensy 4: Global vs local variables speed of execution

    Right shift the number two times. Or set the analogReadResolution(10) command.
  28. L

    Teensy ADC resolution

    All you need is Amazon!
  29. L

    Teensy ADC resolution

    I think you are going to have far more difficulty with the thermal coefficients of the resistors and pot to achieve 1 part in 8,000 than the resolution. The heat generated by the current through the pots and resistors will not be insignificant.
  30. L

    Is a decoupling capacitor necessary for 5v in on the Teensy 4.0?

    I think it does. We'll let others comment on that. Generally, the stuff Ido doesn't have that kind of loads.
  31. L

    I need electronics help. #hx711 #teensy3.2 #logic levels #noise #scopePics

    To test the load cell I would disconnect it and substitute resistors of the same value. If the noise continues, then it's in the HX711 circuit. Is the load cell a full bridge? Did you epoxy this onto the beam?
  32. L

    Is a decoupling capacitor necessary for 5v in on the Teensy 4.0?

    I agree. At least look at the data sheet and see what they recommend. Also, the 1,000 µF cap raises an eyebrow. What are you using for the supply? Typically I use a 10 µF cap in parallel with a .1 µF cap. The 10 µF will reduce power supply ripple and the .1 µF reduces noise. They are two...
  33. L

    Teensy 3.2 Clockspeed Question

    When I change the CPU Speed in the Tools menu I would expect that some of the MCG registers would be changed. Once I compile I do a Export compiled Binary. However, when I flash the chip from my J-Link and subsequently examine the memory using J-Mem I was expecting to see MCG_C2 and/or MCG_C5...
  34. L

    Teensy 3.2 DIY board bringup - USB not working

    That looks really good. How many layers to your board?
  35. L

    MacOS version of teensyloader disconnecting regularly

    I've not had that issue with High Sierra 10.13.6. I'm running Teensy 1.48 and Teensyduino 1.8.12. Board is a Teensy 3.2 Then again, my files are not that big. 11,776 bytes of flash and 4880 bytes of dynamic memory.
  36. L

    Teensy 3.2 Crystal Oscillator Question

    Paul, Thanks for the reply! I'll give that a try. Also, being new here it has taken a little time to understand everything you have done here. I just wanted to say that I am both grateful and amazed at the work and heart you have invested here. You should very proud of what you have...
  37. L

    Killed my First Teensy 4.0

    Are you sure it wasn't the switches? Didn't you say you may have miswired them? You wrote, "The switches were attached to GND, 3.3v and Pin 14 (A0)." Any chance that when you pressed a button it shorted 3.3 VDC to ground? If you no longer have 3.3 VDC on the board, then either something is...
  38. L

    key matrix 56 keys, no diodes on teensy 4.0

    I'm glad you got it working.
  39. L

    Does the input have already a Schmitt-Trigger?

    Of course, but a sample size of one isn't very telling, statistically speaking. There may be other factors that could cause that empirical value to change under different conditions, too. That might be a bigger problem if the operation becomes intermittent. I am guessing it may be better to...
  40. L

    Does the input have already a Schmitt-Trigger?

    If you are looking for an exact value, I think it is somewhat arbitrary by nature. The problem is that the Schmitt-Trigger is defined internally to the chip, not some dedicated manufactured part. If you need to know, and it's not in the chip's data sheet, then I would put in a request with...
  41. L

    Multiple Instances of USB HID om My Mac

    When I run the Joystick example program on my Mac I get three instances of the program, only one has the actual joystick data. The other two lists are 'Vender Defined Usage 0x1' and 'Vender Defined Usage 0x75' respectively. I found the file where the the PRODUCT_NAME is defined (usb_desc.h)...
  42. L

    Does the input have already a Schmitt-Trigger?

    Why do you ask? The reason I ask is because what you are asking may not be important to what you need to do. Can you explain what you are trying to do?
  43. L

    key matrix 56 keys, no diodes on teensy 4.0

    If this is a time-critical event, then your friend is going to be assembly code. However, I would be hesitant to rely on any library routine to do the debounce without careful scrutinization of the code and knowing how often it is called. Typically, what I do is scan each row into a structure...
  44. L

    Teensy 3.2 Crystal Oscillator Question

    Is there any reason that one could not use a 16 MHz oscillator instead of a crystal for the external clock? I am assuming that the oscillator could drive pin 32 (PTA18)m directly and leave pin 33 (PTA19) disconnected. I can't seem to find details in the MK20DX256VLH7 datasheet.
  45. L

    MKL04Z32 Boot Loader for Teensy 3.2

    Can anyone tell me what pin # 9 (PTB1) does on the debugger chip? It connects to the MK20DX256VLH7 pin # 24 (PTA2). Also, PTA6 on the debugger goes to the Micro-AB USB connector pin 4, which I think is USB OTG or some such thing, but not sure what role it plays here.
  46. L

    Teensy 3.6 Custom - Serial Number

    Ah! I understand now. Something like this? https://mcuoneclipse.com/2013/11/30/kinetis-unique-identification-register/
  47. L

    Programming a Blank MK20DX256VLH7 chip

    I'm trying to understand how to program a custom board with a MK20DX256VLH7 chip (same as Teensy 3.2). There is no boot loader chip on the board, so I was intending to program it via SWD pins using a Segger J-Link. However, I am wondering if my thinking is a mistake. Also, can the Arduino IDE...
  48. L

    Teensy 3.6 Custom - Serial Number

    I'm a little confused here. What are the Program Once Registers? Are these on the target MCU or the boot loader chip?
  49. L

    Teensy 3.6 Custom - Serial Number

    Can you put the debug chip into reset? Seems to me that someone else tried what you are doing and found that putting the debug chip into reset via air rest pin caused the rest of the lines to try-state.
  50. L

    Trying to Debug Teensy 3.x Joystick Software

    Thanks again. Looks like I got what I needed working! :cool:
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