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I had this problem about 10 years ago with MX-64 servos on a camera stabilizing platform using a Mega2560. The problem arises if the TX and RX pins are tied together. It transmits OK but...

I normally run with 12-bit resolution capturing a synchronized pair in both the T4.1 sonar and T4.0 hearing aid projects. Just for kicks, I lowered the resolution to 10 and 8 bits and got the...

Reading the registers for A2 and A3 shows a value of 0x38 both before and after configuring the two ADCs in setup.


///// ADC0 ////
adc->adc0->setAveraging( 4 ); // Set number...

Thanks for the info. It did not solve my problem but discovered that disabling a DAC write command reduced it considerably. Need to get the scope out and find the source. Might be the SPI operation...

@JBeale
I have a similar problem with a T4.0 and T4.1. I get a sharp ringing spike repeating at 1KHz - 1.2KHz. How would I apply the IOMUXC code to A2, A3, and A9?

I'm working on a sonar project at the moment but will be back on the hearing aid shortly. It will not use the shield but instead have an MCP4922 chip for the dual channel DAC. That chip interfaces...

The problem has been very irregular. Sometimes a change seems to work then several hours later, the problem returns. USB adapter speed does not seem to be the answer as it's the same on a Win7...

Just found that out as there's not difference in output speed for settings from 1200 to 4M. If I set the rate in the device manager it keeps jumping back to 9600. Where is the rate set?

The same Win7 box worked with a T3.6 several years ago at 4Mbps through an FTDI adapter. As long as I can get things to work at 19200 during development then I'm OK for now. When the Win7 box goes to...

More info. The T4x has the same problem in Win10 directly or through a USB3.1 hub. However, dropping the serial baud from 115200 to 19200 seems to have fixed the problem. Also, setting CPU speed to...

Several users have been seeing problems with the T4x uploading and getting data from the serial monitor. However, when the board is on it's own, it seems to be OK. I just tried my T4.1 running the...

After a day of working with the "fix", I'm going back to the original version of usb.c. During the morning, the fix would give me some serial printout after an upload but generally not all of it. The...

Found and fixed. It helps as I now get a run and print after upload. The first time the print is chopped off before the end but the reset button on the board gives a complete print. This problem is...

Tried a USB3.1 hub and a USB2 active extender. Neither solved the problem and now the board will not work correctly at 396MHz.

I find numerous usb.c files but none contain the mentioned function, usb_transfer_status. Do you have a location for this file? What will happen if running a lower speed device with the file change...

The Win7 box is about 15 yrs old and already sluggish. Going to Win10 is not an option at this point. It will eventually run as dual boot with Mint Mate or LMDE. I see the same problem on a new Win10...

Hardware/software: Acer desktop, Win7, IDE 1.8.12, TD 1.52.

You're right. With my T4x boards, I get all kinds of problems. Port not found, port busy, no upload, upload but no printout, partial...

I have this problem regularly with the T4 & T4.1. It will work for hours then fail several times then OK. It happens on W7 and W10.

Instead of using a pot for the voltage sample, monitor a capacitor charging through a large value resistor. You can use a digital output pin as the source and put the code in loop() for repetitive...

Unfortunately, I have little experience using DMA or internal hardware register commands so can't help much there. There are several members on this forum that can steer you in the right direction....

You can follow the progress of the T4.1 here.

https://forum.pjrc.com/threads/60532-Teensy-4-1-Beta-Test?p=237530#post237530

The T3.6 will probably handle your project nicely. Watch for updates as the T4.1 is due shortly. It has nearly all of the pins brought out to the board edge like the T3.6. You could develop your...

That should work fine. If the math is float intensive then consider the T4 with the internal FPU. One thing I've found strange is that the ADC sync example does not work if you use A2 and A9 as...

I would start by doing some timing tests to determine how fast you can collect data. Doing captures sequentially will introduce phase errors that you need to know. Here's a sketch to see how fast you...

I've had similar problems with my T4 on both Win7 and Win10. The device can work correctly for hours then not run or upload a new sketch. I see error messages similar to port not found, port not...

Maybe the 15 sec rule applies.

I'm out of ideas at this point. KurtE's experience may help you now that you've gotten some response from W10 and the T3.5.

Watch the device manager then plug in the T3.5. If it shows up in any category then use the uninstall device button. Unplug the T3.5 and reboot. Start the device manager and try again. If W10 sees...

Uninstalling a driver then rebooting gives the OS another chance to get it right. This scheme works in many cases of hardware problems. Do you have another Teensy to see if it's the OS or the device...

That's the latest but you might install Teensyduino again. Maybe the driver did not install correctly. Do it without the T3.5 connected and reboot before trying the IDE again. Run the device manager...

What version of Teensyduino are you using? The driver for the Teensies is part of that package. Mine gave me strange messages when first plugged in but eventually worked. Paul will have a better...

I had that problem initially when first connected to my W10 laptop. It seemed to be related to the selected port. Sometimes it was a human USB device then it was a serial device at a particular port....

I see the same problem on W10 with my T4. It can be working fine for hours then suddenly won't communicate with the serial monitor. The error message says the port is not available. Sometimes,...

You can also create an H-bridge with opto-couplers. The ILQ74 has four sections with a max current of 60mA. With two Teensy output pins, you can get three states, in, out, and dormant. The circuitry...

Excellent. I'll add it to my collection and try it in the sonar project.

Thanks

I get high values near 2^32 but quite variable with each reset. Guess I can't make any use of that location.

Thanks for the link. I don't quite understand it all but it's encouraging that these kind of things can be done.

How would one go about reading a DWT register at address 0xE0001004? I'm guessing a...

I see that in the ARM reference in the previous link that all the DWT values are 32-bits based on the address jump between each item, 4 bytes.

And just for kicks, I wanted to prove to myself that...

The cycle counter is probably crucial for internal operation so changing it's value might kill a program. I would expect the value at that address, 0xE0001004, to be related to micros().

I guess...

I knew it would not be feasible with 32-bits. A 64-bit value counting 10 nsec would last ~5849 years. Is there any other variable size between 32 and 64 bits that can be handled? Would the...

Is it possible or feasible to create another clock function for the T4 with higher resolution? It might be called Nanos() with a 10 nsec resolution. I envision something like F_CLK / 6 with overflow...

If the ISR for each event does the same thing then OR the interrupting signals together with a pull-down through 1N4148 diodes to a single input.

Use a separate interrupt routine for each event. Create a global variable, isrID, and make each ISR set the variable to it's appropriate ID, 1-4. In loop(), check that byte in a switch statement and...

At this point, I've not made a decision either way. I'll look into the audio tutorial some more and if I feel comfortable enough with the programming then I'll go that route.

Thank you for all of...

I'm using the T4 dual ADC in sync mode to capture both channels in 6.3 usec(167Ks/s). Adding two 3-pole HP Bessel filters sequentially adds only 0.4 usec. There will be some software mixing of the...

Will this be compatible with the Adafruit board?

https://www.adafruit.com/product/3678

I looked at that and found a nice board from Adafruit that would directly replace the function of a pair of MCP4725 boards. However, the library was written for the Due and other CPUs that show up as...

Problem Solved
My Owon SDS-7102V scope found it all. It turns out that Wire1 commands do not work or they use different pins than A4 and A5. None on the top of the T4 were active. I changed...

It's now responding to speed changes by moving the Wire1.setClock() to just under the Wire1.begin() in the DAC library CPP file. However, I don't get the right output voltage and by calculation, it's...

When using Wire, I had no control over the speed. When switching to Wire1, my loop time dropped from 384usec to 109usec for 20 passes. However, using Wire1.setClock() does not produce a change in...