Re: teensy 4.0


pa2pim@...
 

The form factor of the Teensy 4.0 might be the same but it's also considerable faster.

I've used a Teensy 3.5 and implemented lot's and lot's of hard- and software changes.

One of the myriad of things I ran and run into is that some libraries can't deal with the higher execution speed.
Most noticeably now it's the interface with the LCD.
With a Teensy 3.5 @ 120 MHz the info on the LCD get's garbled at times.
The workaround so far has been to set a 48 MHz clock in the Arduino IDE instead of the default 120 MHz clock.
I've not stuck an oscilloscope in that part yet since the workaround is fine for the moment.

On a LoRa project I had a similar issue with the higher clock speed of the Teensy with the SPI interface of the Teensy 3.5
It was diagnosed that the Device select line was deselecting the device before the data transfer was done, see https://forum.pjrc.com/attachment.php?attachmentid=10948&d=1499109224  

I'm currently also using the I2C/TWI lines.  So far I've not seen issues with using that, at least not with the Si5351 signal generator chip controlled by the Teensy.

Next is the issue of signal levels. The Teensy 3.2 can handle 5V signals, the 4.0 can not, see https://www.pjrc.com/teensy/techspecs.html
The encoder and most of the other peripheral hardware are powered with 5V.

Now it's certainly doable to run some of them on 3.3V and/or use level converters.
Despite that the Teensy 3.5 I use can also handle 5V on it's IO pin's, that's what I did and it works fine.

So can a teensy 4 be used?

Probably yes but be prepared for some hard- and sfwr tweaking.
If you go that route have a look at the 4.1 first, same voltage level issue but lots more IO pin's which comes in very handy.

73 Pim , PA2PIM

Join loopController@groups.io to automatically receive all group messages.