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Thanks for the pointer to "Crash Report." :-) Using the CrashReport output, I followed some twisty paths to find my .elf file and ran "addr2line" which showed that the crash occured as soon as barometer.begin() was called. To try to figure things out, I created a sketch doing copy-and-paste...

Here's the code: The SparkFun code - which ran fine on the Arduino Uno - did not have the Wire.begin() line. I added it here, but it still hangs on the Teensy 4.0. /****************************************************************************** t5403_demo.ino Demo Program for T5403 barometric...

I'm having a problem interfacing a SparkFun T5403 Barometer to my Teensy 4.0. If I connect the T5403 to an Arduino Uno and run the example program, all works fine. But, if I connect the same board to my Teensy 4.0, the program hangs. (???) I'm using the Teensy Wire() library and have the...

Here's the (working) test code. Not sure how to get this to display in the message body(?)

Thanks again! Here's the pendulum clock design that inspired my project: https://en.wikipedia.org/wiki/Shortt%E2%80%93Synchronome_clock And when I was first working on this project (10years ago!) I found lots of good information here: http://www.leapsecond.com/hsn2006/

Thanks manitou! I used your code as a starting point for my code development and it's working as expected!

Thanks for that insight and pointer! It seems NIST has lots of relavant information for this kind of stuff - I also found this paper: https://www.nist.gov/system/files/documents/calibrations/ie79-7.pdf . Table 1 shows typical stability for commercial Rubidium clocks at 10^-13 @ 1 day and...

Update: After doing some searching on the forum and the Processor Reference Manual, it appears the GPT2 clock input (GPT2_CLK) and capture control input (GPT2_Capture1) are easily accessible on the Teensy 4.0 board. Just ordered a Teensy 4.0, so should be able to do some testing in a few days...

Hi Paul - Thanks for your quick response! I'll take a look at the FreqMeasure library - sounds like that should get me started - but what I want to do is a little different than what you described... I want the timer CLOCK SOURCE to be the external 10MHz Rubidium Clock - so the timer would...

Thanks in advance for your help with this! I'd like to use a Teensy 4.0 to implement a 32-bit counter driven by an external 10 MHz clock - the clock source would be a Rubidium Frequency Standard. The counter would be free-running, and when an input pin goes high, the current 32-bit counter...

Hi, When you look at the schematic and PCB layout for the Audio Shield, there is a ferrite and two caps connected to the VDDA input pin on the IC. Removing the ferrite disconnects the VDDA pin from the existing 3.3V power on the Shield. The SMD cap right next to the ferrite is one of the caps...

Hi Chip, The part your arrow points to is indeed the ferrite. I did exactly what you are describing and it dramatically reduced the noise! I built a linear supply and connected it across the VDDA cap just to the left of the ferrite in your picture. I also built a 5V linear supply to power...

I used the Bass Preamp at a gig this weekend and it worked pretty well. The power supply noise is essentially gone - now there's no more background noise than with any other guitar/bass rig I'd typically use. Pretty happy about that! I've also eliminated another source of noise: Chatter from...

Thanks for posting the simulations! I was aware of the LF roll-off issue. When I picked the 0.22uF output cap, I thought the pots I had were 25K, but it turned out they were 10K :) When I realized that, I decided to just go ahead and test it as-is before I got the soldering iron out again...

Here's what I did for the preamp. I used LND150 MOSFETs because I've been using them for other experiments - they're good up to 600V :-). Other FETs would probably work fine with some resistor tweaking. I'm running the whole system with a 12V supply, so I used that voltage (with an RC...

A couple years ago I started working on a bass guitar preamp using a Teensy 4.0 and the Audio Shield. I was able to try lots of different topologies for gain and tone controls and used it on stage for a few live gigs(!), but there was always some annoying background noise in that setup that I...

Does moving the Audio Shield away from the Teensy reduce the noise floor on the audio outputs? Also, would there be any possible noise advantages to running the shield from a seperate 3.3V supply? I experimented with a Teensy (4.0?) and Audio Shield a couple years ago and always had some...

Hi Frank, My thinking was that the biquad object in the library would be the easiest way to implement the first order filter, since its uses a subset of the biquad structure (most of the biquad coefficients are zero). I think any other approach would require me to somehow handle the processing...

Apparently there are lots of ways to calculate coefficients for digital filters! :) I found C code examples for a pair of first order filters (thanks Google!) that also seem to be working fine. I'm running these on a Teensy 3.6 in the range of 100Hz - 2kHz. double coefficients[5]=...

I've been experimenting with first order filters for a bass preamp. I've been able to get a Low Pass filter working just fine by calculating the coefficients with this code: // -------------------------------------- // Calculate first-order LPF coefficients double coefficients[5]=...