NewLinuxFan

I noticed that the Teensy 4.0 and 4.1 have a special processor for floating point math. With Arduinos I remember that it was always faster to use integer math, but does it really matter with the Teensy 4's? Sometimes C libraries that do...

And there's contact resistance to consider, should be milliohms but can be > 0.1 ohm in bad cases, and there are 4 contacts in the power/ground cable wiring all in series too...

I've only connected nominal 5V regulators, but that's a good point because somebody else could theoretically hook up 3.6V or 5.5V. USB power wires vary from 20 to 24 AWG and lengths usually vary from 3 to 15 feet. 6 feet (black + red wire) of...

I use a SOD-523 / SC-79 package style which is pretty small, but fits nicely on the pads. I normally still mount it at an angle to ensure good clearance for the pins. If you are connecting both VIN and USB power without the mod, you are...

I used to scratch that out, but then I realized it doesn't matter and just creates more work and inconvenience. My USB cables never get warm from the voltage difference.

You should be able to, but you may need to initialize SD after you set up SPI2 to use the alternate pins.

Wait, I think I get it now: the darker green is the default pads and lighter green is the alternate pads.

Thank you. Sounds like I have to re-solder to different pins.

Got it working! Just needed this: SPI2.setSCK(49): SPI2.setMOSI(50); But it looks like I can't use the SD card slot at the same time?

Thanks for all the tips. The through-hole IC I found works great. However, I can't get the SPI2 data or clock signals from pads 49 and 50 on the bottom (photo includes hot glue for strain relief). The same test code works fine for SPI and SPI1...

If you are still looking for a level shifting solution, this SN74LVC4245A based breakout module would work for you. https://protosupplies.com/product/hi-speed-8-ch-logic-level-converter-module/

Because I often use Teensy to interface to SoCs, I keep some TI TXU0n0m, 74LVC1T45, and 74LVC8T245 voltage level translators in stock. Each side has their own supply (but share the same GND, these are not isolators), and you should add a 100nF...

I haven't had problems with the higher data speeds of the APA102 or SK6812 LEDs. My Infinity Mirror Clock has a string of 120 APA102 LEDs, updated 120 times a second. My Ring Clock has a strand of 276 APA102 LEDs and a second strand of 222...

I see some of the newer Arduinos are using AI for image recognition. That would be nice to use in Teensy. (Without the latency of an operating system.)

The Uno is better paperweight because it's bigger. 🙂

I can't see the schematic in KiCAD (it might be an Eagle file), but I know from experience that the Teensy 4's use more power than the Teensy 3's, so a linear regulator without a heatsink that is using a much higher voltage such as 12 or 24V to...

74HCTxx series will do the 3.3 -> 5.0V conversion reliably (74HCxx won't, according to the datasheet)

If you’re OK handling SOT23-6 parts, then my favourites are 74HCT2G34 (dual buffer), 74HCT2G04 (dual inverter) and 74HCT1G86 (single XOR, useful if you’re not sure if you need an inverted signal or not…).

This looks easy to use and fits into breadboards and common prototyping boards: https://www.digikey.com/en/products/detail/texas-instruments/SN74AHCT126N/375812 (It would be really nice to have a Teensy prototyping board with SMD pads connected...

That's great to hear. Did you have any issues with higher data speeds or idling between packets?

I've used a TXB0104 breakout on many projects to control APA102 LED strips without problems. One example is my Infinity Mirror Clock

Thanks for the tips. Seems like I could just put a couple 6N137's at the LED strip and send the signal over a decent distance for whatever the dataspeed is, with current-limiting resistors to send 5 or 10mA to the infrared LED's.

So you only need 3.3v ->5v conversion? Pretty much any 5v logic chip will work for that, as long as it reads a 3.3v input as high (and doesn't have internal 5v pull-ups). Bidirectional shifters are notoriously unreliable, TXBs are "ok" for 1:1...

I'm a bit sad that the Prop Shield LC is discontinued and the full Prop Shield is out of stock, though I have to admit I've never used the amplifier, memory, or motion features, just the level shifter for SPI-based LED strips. I'm wondering if...

That's an interesting idea. I have it dialed in the get 16 bits at the highest frequency, but there is some range to play with. The question is how often the pulse edges would align.

Thanks! I'll take a look. I use up to 18 pins sometimes, but if I can change half of them that could reduce the noise.

I'm a bit slow to respond because I was sick. Appreciate the replies. It's a single power supply and analog RGB strips connected to MOSFET switches. (Other projects of mine used digital LED strips but not this current project.) Very basic...

If I'm not mistaken, I believe there's special chips you can get that adds jitter to the output. I know of at least one company that did this in their LED driver product so that they could pass noise certification.

With the analogWrite() function.

Is there a simple way to reduce power supply noise when several LED strips are at approximately 50% duty cycle (the loudest). I'm thinking a very basic solution would be to have half the outputs align leading edges and the other half align...