Confusion on the Teensy 3.2 Schematic and Pinout

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Agriculex

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Hello everyone.

I'm looking at implementing a custom Teensy 3.2 board for my project and planning to buy PRJC's MKL04 chip for the bootloader. Right now, I'm copying the schematic and mapping the pinout but ran into some uncertainties.

Teensy3.2Sch.JPG
From the image above, the value of L1 and L2 are not given. Can someone from PRJC please provide the values for them? Also what are these "termination points" that I have also circled in red? I've never seen them before in other schematics.

As for the pinout:
Teensy3.2Pinout.JPG
It states that TX & RX are pins 3 & 4 respectively and if I remember correctly, TX/RX is used in Serial.[function] in the Arduino code. But I'm sure pin 3 & 4 are not used for that. Can someone clarify that part up?
Also, I see some duplicate pins greyed out (like RX2 & TX2 on D26 and D31). Why is that there?
 
Its all colour coded, 3&4 are CANBUS Tx/Rx, not Serial Tx/Rx
L1 and L2 are ferrite beads I think, it does say "Ferrite" on the layout!
 
Still have some confusion on the faded color duplicates for SDA0/SCL0, Serial 1, and Serial 2.

Those are the non-default alternate pins.

See the setTx() and setRX() functions documented for serial here:

https://www.pjrc.com/teensy/td_uart.html

and the similar setSDA() and setSCL() functions documented for I2C here:

https://www.pjrc.com/teensy/td_libs_Wire.html


Also what are these "termination points" that I have also circled in red?

Those are test points. They're used by a bed-of-nails test fixture at PJRC as each board is fully tested. If you look at the bottom side, you'll see small round test pads. There is no further documentation about which points on the schematic are which locations on the PCB. They're not intended for anything other that product testing at PJRC. But if you *really* want to use them for something, I'm sure with the available documentation and a little legwork you can sort them out.
 
Those are the non-default alternate pins.

Makes sense now! Still learning new features as I'm used to the AVR Arduinos. Can you explain the missing values on L1 and L2? By the ref designator and symbol, it's an inductor. The schematics for T3.5 and up have values to them albeit no units. I'm assuming it's uH by default?
 
Maybe it's time to update the Teensy 3.2 card names for the CAN pins. On later cards the prefix "CAN" was added because several people were confused by the names being similar to serial. But the 3.2 documentation card has remained the same all these years...
 
Maybe it's time to update the Teensy 3.2 card names for the CAN pins. On later cards the prefix "CAN" was added because several people were confused by the names being similar to serial. But the 3.2 documentation card has remained the same all these years...

And if you are going to update the card any way, it may be a good time to document the I2S pins.
 
A major reformatting isn't going to happen. But there's plenty of white space around those 2 CAN signal names, so enlarging them is a simple change.

The back side also still says MacOS 10.8, which is technically still true (even 10.7 can be made to work) if older versions of Arduino are used. But I'm gradually updating all the cards to say 10.10 in anticipation of someday dropping the old MacOS installer.
 
Makes sense now! Still learning new features as I'm used to the AVR Arduinos. Can you explain the missing values on L1 and L2? By the ref designator and symbol, it's an inductor. The schematics for T3.5 and up have values to them albeit no units. I'm assuming it's uH by default?

Ferrite beads are generally not crucial, they don't really have a value as they are very frequency dependent and have varying impedance that's
part inductive and part resistive. They are used to attenuate high frequencies by being very lossy at those frequencies.
 
The ones we use on Teensy 3.2 are rated to 600 ohms at 100 MHz.

@Agriculex - It is standard industry practice to specify ferrite beads using impedance at frequency rather than by inductance. If you are new to electronics and not familiar with ferrite beads, perhaps search for them at Digikey or other sites.
 
The ones we use on Teensy 3.2 are rated to 600 ohms at 100 MHz.

@Agriculex - It is standard industry practice to specify ferrite beads using impedance at frequency rather than by inductance. If you are new to electronics and not familiar with ferrite beads, perhaps search for them at Digikey or other sites.

Got it now and yes I'm fairly new to electronics. Thanks for the answering my questions!
 
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