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  1. K

    Help Understanding This Code . . .

    I was curious and have lots of test cases laying around, so I ran a few tests at132.9MHz as reported by the software using the PJRC PSRAM test combined with a simple Flash test that formats the Flash and writes/reads a file. 8MB APMemory = PASS. Test time went from 36.24 secs to 25.35 secs...
  2. K

    Measuring RPM using a 3144 hall effect sensor gives odd +/- error

    The 3144 Hall Effect sensor itself requires at least 4.5V power. Perhaps try powering the module from 5V and pull the output up to 3.3V as you have it for compatibility with the T4.0 to see if it helps to stabilize the readings.
  3. K

    Power problems with T4

    You are asking too much from a 9V battery. Teensy 4.0 by itself draws about 100mA. 9V batterys have high internal resistance and are not designed to supply that much current. Here is a website which shows some 9V batteries with 100mA (and higher) current draws...
  4. K

    Need help troubleshooting RA8875 which works in a wired prototype, but not in PCB

    Hi Mark, I am using the same TFTM070-5 display with capacitive touch on SPI1 as you. Some of your posts help me get going with my own setup, so thanks for that. I am wondering if the FT5206_gesture example works OK on your setup. On mine, the 2 finger gestures like zoom in/out work alright...
  5. K

    Esp32 & teensy 4.1 not communicating

    For the ESP32, you will need something like this. #define RX2 16 // Teensy 4.1 is connected to serial port #2 #define TX2 17 void setup() { Serial.begin(115200); // USB port Serial2.begin(9600, SERIAL_8N1, RX2, TX2); //Port connected to Teensy 4.1 }
  6. K

    U4 going short on teensy 4.1

    Are you using the Teensy 3.3V regulator output to power a lot of peripherals? There has been some evidence that hanging large amounts of capacitance on this output can sometimes cause reverse current flow through the regulator during power down. If that is a possibility, more info on that...
  7. K

    Diode orientation for Color 320x240 TFT Touchscreen Purple Board?

    The diode is a reverse voltage protection diode, so it would be placed so that the cathode with the line is on the right towards the regulator. I don't know anything about this board, but it doesn't sound like you got the right board. The last 5 pins on the display are used for touch, so...
  8. K

    Powering Teensy Audio Board Externally

    It is fine to power the audio from a separate 3.3V regulator as long as the grounds are common. That is how I do all my boards.
  9. K

    Teensy 4.0 Powered by Anker PowerCore 10000 Portable Charger

    Yes, you can power a project using a portable charger like that through the USB on the Teensy. It won't hurt anything as long as total current is kept below about 500mA or so. Cutting the VUSB trace is done if you are supplying an external power source to the VIN pin (whether from a battery or...
  10. K

    Future Teensy features & pinout

    PJRC is hardly alone in this cash-flow situation. I have some visibility into the contract manufacturing world and many/most companies are in the same situation. It's going to take a couple of years for this to sort itself out completely, especially if consumer spending continues to trend down...
  11. K

    Teensy 4.1 Proto System USB Host Problems

    I'm glad you got the issue sorted out. Since you are working with audio, I will have a MIDI interface adapter that will be available for it in a couple of weeks that you might find useful. I also have another version of this product in process which is designed to facilitate the building...
  12. K

    Teensy 4.1 Proto System USB Host Problems

    This is Ken from, please look at my post above yours. Your readings up in the M Ohm range are all fine, the only issue is (D+ <> Gnd 0.5 Ohms) With the Teensy removed, please measure the resistance between ground and D+ on both the Teensy and the Baseboard to see which one...
  13. K

    Teensy 4.1 Proto System USB Host Problems

    Hi Donald, I sent you an email with some troubleshooting info yesterday, put perhaps it went into your SPAM folder. If you are in fact measuring a short to ground on the D+ pin of the USB Host header, that would be your issue. You mention also trying to measure with power applied, but...
  14. K

    Board size (and how to reduce it)

    I once had to cut large 4-layer boards down in size and found that a bandsaw with a fine tooth blade did a good job. Main issue that came up was that the internal power/gnd planes would occasionally short due to slivers of metal bridging them from the sawing motion. A visual inspection and...
  15. K

    RA8875 Up/Down/Left/Right touch gesture not working

    I am working on a new product which includes an RA8875 7" LCD with capacitive touch from BuyDisplay (ER0TFTM070-5) on the front side and mounts a Teensy 4.1, adapter boards and various I/O on the back side. I am using the RA8875 library that comes with Teensyduino. The LCD is on SPI1 and touch...
  16. K

    T4 overheats when connected to my PCB

    If you can't attach a PDF, try capturing the schematic as a PNG image. PNG preserve the image detail better than JPG.
  17. K

    Teensy 4.0 burning out... how do I find out what the problem is?

    Looking at your diagram, I notice a few possible issues. The maximum allowable voltage on the VIN pin that feeds the RT1060 CPU chip and 3.3V regulator is 5.5V. When you say a 5-6V power bank, you may be damaging those chips through over-voltage if it is running over 5.5V. If that is the...
  18. K

    ILI9341 And XPT2046 Not Working Together

    Using the display rotation of 1 and touch rotation of 3, the coordinate systems between the two should already match, so I don't think you want to cross map the X/Y. If I change this dpt.y = map( pt.x, 263, 3844, DY_MIN, DY_MAX ); // Put X-axis data into Y-axis result...
  19. K

    Audio Tutorial Assembly Issue

    The soldering is definitely looking better. Did you also remember to solder the stacking header on the bottom side of the Teensy to complete the connections?
  20. K

    ILI9341 And XPT2046 Not Working Together

    I have a setup with the ILI9341 and XPT2046, but using a Teensy 4.1 I ran your example program and just changed the two CS pins to match the pins I am using. When I compiled the program using 1.8.19, it gave me some errors about multiple definitions in Adafruit_GFX.h so I commented out the...
  21. K

    Teensy 4.0 I2C stops - issue in my pcb?

    Ignore that, I misread your note and thought you had hooked up to pins 15/16 instead of 16/17. Agree there should be no conflict on pins 16/17. You mentioned that it seemed to work better with the LCD in place. It looks like the LCD is at the end of the I2C chain, so perhaps adding pullups at...
  22. K

    Teensy 4.0 I2C stops - issue in my pcb?

    When you moved the SDA/SCL from pins 16/17 to 18/19 with short jumper wires, did you cut the traces going to 16/17 and run new wires from the T4.0 to 18/19? Wondering if you might have shorted the two I2C buses together if you just jumpered from 16/17 over to 18/19. .... Actually looking...
  23. K

    5V 3V3 VUSB power supply struggles - Teensy4.1 - what kills my NCV8186AMN330TAG ics?

    Good point about the reverse current MOSFET on the input side. That should prevent any current that would backflow to the power source, but perhaps there is a sneak path for current through the USB1/2_VBUS inputs on the RT1060? It looks like those inputs might power an on-chip 3.3V regulator...
  24. K

    Switching a 2.2Kw 240V kettle element using a Teensy

    The windings of the heater would be relatively few in number and the resistive nature of the wire would help dampen any inductance effect. Being a large gauge wire has little effect. You can play around with one of the on-line inductance calculator to see the basic effect of playing with the...
  25. K

    Switching a 2.2Kw 240V kettle element using a Teensy

    You don't need a flyback diode switching AC to a resistive element. You would need a buffer of some type like a transistor to drive the relay coil to boost the drive current and perhaps the drive voltage. You can't drive it directly off a Teensy. Solid State relays are nice like AlanK...
  26. K

    PJRC Server Change

    I use WordPress for my site. Much easier to maintain that working with HTML. If you use the new blocks in WordPress, you can copy over your tables easily with this steps, no special plugins required: View the current page source in your browser of choice (I use Chrome) and copy the HTML...
  27. K

    USB host port on Teensy 3.6 measures no 5V out

    The USB Host 5V has a logic controlled power switch on it. It is normally OFF and turns ON when you call the USBHost begin() function.
  28. K

    Power delivery issues with JST vs dupont cables

    Definitely sounds like a wire gauge issue causing excessive voltage droop when the LEDs kick on. If the JST wires come from China, which include most sold on Amazon, it is common practice for them to be labeled with a larger AWG than they actually are. I have JST pig-tail assembles here that...
  29. K

    checking Teensy for partial failures

    I think that kind of project only makes sense if you do it because you enjoy the challenge. No matter how good you are, you almost certainly will not be able to test as thoroughly as PJRC does when the boards are initially manufactured. I would image that several months were spent developing...
  30. K

    ILI9341: how to increase intensity? (100 ohm resistor used)

    That pin is a logic input that simply switches a transistor ON/OFF. That input already has a 1K ohm series resistor, so the 100 ohm resistor doesn't really have any practical use. When the transistor is turned on, an on-board 10 ohm resistor is what is actually limiting current thru the...
  31. K

    All my eggs in one basket

    About 9 months ago, I was talking to an acquaintance that works at one of the well known chip manufacturers here in the USA about the chip shortages. They don't do CPUs, but they do many of the popular peripheral chips. In their case, wafer production at their US facilities was not an issue...
  32. K

    Teensy 4.0 WS2812 slow.

    Gotcha, I glossed over the fact that you were also going to use the Audio Adapter. I made one project that used the Audio Adapter and and was also running WS2812 LEDs and ran into the blocking issue. In my case I found that it worked easier/better to just use a separate mini MP3/WAV file...
  33. K

    Teensy 4.0 WS2812 slow.

    Why not just use the same code you have shown for the Nano in the Teensy 4.0? It will also run faster. You also don't have to use the Octo2811 adapter to use the Octo2811 library. The adapter is basically just replacing your 74AHCT125 plus throwing in a 100 ohm series resistor.
  34. K

    mosfet voltage drop

    The CD74HCT125 will work fine and your basic pinout looks correct. Since the device has 4 separate channels, if you have any unused A inputs, they should also be tied to GND or VCC and the outputs left unconnected. Basically just don't leave inputs floating per the datasheet.
  35. K

    mosfet voltage drop

    The basic issue as you guessed is that the 3.3V drive is not high enough to fully turn on that MOSFET while the 5V was. If the MOSFET only partially turns on, it starts dropping a lot of voltage when you drive something that requires a lot of current. The easiest path would be to use...
  36. K

    Issues with 4.1 and sound module

    I have seen that when there are signal integrity issues between the Teensy 4.1 and the audio adapter. It seems like even a momentary issue with MCLK can put it in a state giving that screeching noise that won't clear until the unit is power cycled. In my case, I had a contention issue between...
  37. K

    Expected Teensy 4.1 operating temperature

    The Ethernet DP83825I transceiver chip can draw quite a bit of power when active - up to 41mA per the spec sheet. With a decent heatsink and a little air, you might see 8-10C drop. Besides what has already been mentioned, you can pull some heat out of the 3.3V regulator by running the 5V VIN...
  38. K

    TeensyLC to Touchscreen ILI9341 connections

    I am unclear as to which touch controller you have. If you are using an ILI9341 with the XPT2046 touch controller like you linked to on the PJRC website, here is a simple program that should work on the LC. You will need to install the XPT2046_Touch library using the IDE library manager if it...
  39. K

    ILI9341 not working on Teensy 4.1

    It still looks like you have reset connected to a digital pin (D8?) rather than 3.3V, but hard to tell for sure from the pic.
  40. K

    ILI9341 not working on Teensy 4.1

    It looks like you may have pin #6 tied to RESET on the display? If so, unless you are modifying the program to drive that pin high, the reset pin will be floating which could give intermittent operation. You can just tie the RESET pin to 3.3V to see if that is the problem.
  41. K

    Color LCD Touchscreen Backlight

    That pin drives a transistor that controls the LED backlight power. Active H to turn backlight on. Can tie to 3.3V or use pull-up to always have on or can use logic control.
  42. K

    Oscilloscope questions - Rigol ds1102e

    I agree that 100MHz, 2-channel will handle most everything you might want to do. 4-channel tends to be more useful when working with analog like if you want to see what the input, output and feedback pins on an Op Amp are doing all at the same time. If you would prefer to buy new, the Siglent...
  43. K

    Is the teensy 4.1 compatible with this breakout board?

    That nRF24L01+ adapter will work fine with a T4.1 and shouldn't cause any damage if connected properly. The nRF24L01+ operates at 3.3V logic but is 5V logic tolerant on its inputs. The main value of the adapter is to make hooking up to the nRF24L01+ pins easier since they are in an unmarked...
  44. K

    audioboard REV d voume pin 15

    The volume control and ADDR are two completely different circuits, they just happen to be drawn next to each other since they both connect to 3.3V. The volume control simply feeds an analog input on pin 15 as you would expect. One side of the pot is tied to 3.3V and the other is tied to...
  45. K

    Anyone mind looking over my schematic and seeing if I’ve set things up correctly?

    Your wiring looks OK. Depending on how many LEDs you are driving, stay mindful of the 5V power draw especially if you are using a solderless breadboard.
  46. K

    multiple teensy on one board

    You need to keep the two 3.3V Teensy regulator outputs isolated. A 3.3V regulator on your baseboard would help to remove the load off the Teensy regulators and would provide a little more protection for the Teensy if you're not sure what all you may be powering from 3.3V on the expansion bus.
  47. K

    ILI9341 Touchscreen stuck on 0,0.

    I have a setup that uses all those pieces along with the audio adapter and there is no issue with the touch working. I am using TD 1.57 and latest ver 1.4.0 of the library For what it's worth, here are the connections I am using on the display. I am not using the T_IRQ pin.
  48. K

    Teensy Audio shield failed after two days

    I don't think you need to be concerned about an inherent quality issue with the product. I install the audio adapter into a system I sell and each gets tested as part of that system. I also have a couple of bench test units that get used and abused regularly with SD cards frequently being...
  49. K

    5V 3V3 VUSB power supply struggles - Teensy4.1 - what kills my NCV8186AMN330TAG ics?

    I have never noticed that reverse current warning with old-school LDO regulators nor have I ever heard of that type of failure issue with those. Many people, myself included, have certainly hung thousands of uF off those without incident or special protection. From the link below it appears...
  50. K

    5V 3V3 VUSB power supply struggles - Teensy4.1 - what kills my NCV8186AMN330TAG ics?

    I think you are on the right track. The LDO datasheet does mention the need for additional protection in the case of extended reverse current conditions when Vout > Vin to protect the output pass transistor. A flyback diode would seem to provide that protection and would be what I would try...