Recent content by jimlux

More interesting data. I have a 15 hour run on the 5 teensys where I logged the temperature (measured by the on chip sensor) and the frequency. The attached plots show the frequency and temp vs time, and then vs each other. There appears to be some hysteresis (which is typical). in ppm terms...

Interesting idea Constantin had there of putting the 32kHz crystal on and using the difference to figure out the temperature. In any case, the crystal is probably an AT cut (since that's popular for room temperature), and the frequency vs temp curve can be very well represented by a cubic...

characterizing the performance of the teensy oscillator In this case, the FreqMeasure library uses the K20's FTM to latch a counter whenever the 1pps comes in, and then it's unloaded by a (timing non-critical) ISR. I was prompted to do this by a comment on the time-nuts mailing list...

I've been running some tests with 5 Teensy 3.1s to measure the onboard oscillator performance. I have a FS725 Rubidium source which puts out a 1pps tick that I run to pin 3 on the Teensy, and running a modified version of the FreqMeasurement example (to just put out raw counts, which is...

<feature request> It would be very useful to have a feature where you can dump output (or output and input) to a file. Right now I copy paste from the Monitor window to a file, then save it. This is just to save me firing up N instances of putty or teraterm, because TyQt is so useful for doing...

Probably.. Teensyduino 1.18 on the Mac (don't know a good way to get the "as installed" version, but the dmg is from August 2014) Although... I was doing some tests on another Windows machine, and I recall seeing the SN come in at 10x(2 LSBs of MAC), so at least one of my test machines has the...

While I was making some cross-platform utilities in python, I discovered that the Teensy USB serial port identifies itself slightly differently on Windows 7 and Mac OSX 10.9 (Mavericks) using the pyserial.tools.list_ports() method, on a Mac it returns '/dev/cu.usbmodem33501', 'USB Serial', 'USB...

An interesting MacOSX feature discovered with TyQT on a Mac. Normally, the serial number of the USB device winds up as the device name (e.g. /dev/cu.usb12345 corresponds to SNR=12345). However, I was testing this morning and found a case where this isn't what happens. I was running TyQt to see...

Yes, indeed, it looks like it might work. I'll have to dig into it some more. Doing the math outside in batches is fine (actually, preferred).

Yep.. looks like IRQ_PIT_CH0 is interrupt #68 (assuming that timer0 uses PIT 0) the UART IRQ #s are 44-50 (IRQ_UART0_LON) then in mk20dx128.c it looks like: // default all interrupts to medium priority level for (i=0; i < NVIC_NUM_INTERRUPTS; i++) NVIC_SET_PRIORITY(i, 128); As you note, in...

Have to look at ADC library.. Our two inputs are on A0 and A1, doing 16 bit conversions.. Originally, the software was coded for the Teensy 3.0, and the timing skew between the two was around 2 microseconds, which is fine for our application (that is, we don't need synchronous sampling...

need to sample both A0 and A1, and DMA library (as of a year ago, when we coded this up) only runs one ADC. The ISR, including the arithmetic operations for a 2 stage CIC decimator, consumes about 50% of the CPU cycles, so that's fine.

You may have seen the news coverage of a prototype victim detection radar called FINDER from NASA Jet Propulsion Lab that detects the heartbeats of buried victims. http://www.jpl.nasa.gov/news/news.php?feature=4578 Here's a NASA TechBrief describing the radar in general (the TSP has more...

I've got an application using Timer0 to fire an ISR that does an analogRead() at 50kHz. The Serial1,Serial2,Serial3 all use interrupts to service their FIFOs. Which one is higher in priority.. in my case, I'd rather the Timer0 be higher priority (and that there be minimal time spent with...

Sure enough, that works. Awesome.