Newbie question about serial pins on teensy 3.2

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gimpo

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Hallo everyone,

I have a good knowledge about Arduino (namely the Arduino Pro Mini - 3.3 V), now I'm approaching with a lot of curiosity to the Teensy world.

Talking about the Arduino Pro Mini, the two serial pins used to upload a new sketch (by using an FTDI device) are actually the same TX and RX pins located on the side of the board (namely pins #0 and #1).
This means that if you have a powered device talking to Arduino with the serial lines then you have to physically disconnect it (or power it off) before uploading the new sketch.
Promini.jpg

Here my question:
is the micro USB connector on the Teensy 3.2 totally independent from the pins of the three serial ports available? In other words, it is possible to upload a new sketch on Teensy 3.2 without disconnecting any powered device wired to a serial port?
 
is the micro USB connector on the Teensy 3.2 totally independent from the pins of the three serial ports available?

Yes.

In fact, a common question for using code designed on Arduino Uno & Nano involves the need to change "Serial" to "Serial1". When you use "Serial" the communication is only to your PC.

In other words, it is possible to upload a new sketch on Teensy 3.2 without disconnecting any powered device wired to a serial port?

Yes.

However, while in programming mode the I/O pins do go to a high impedance (essentially disconnected). Usually this isn't a problem, but if you have a very sensitive serial device you might add a real pullup resistor so it continues to see a logic high at its receive pin while Teensy's TX pin disconnects when you're uploading code.
 
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Teensy 3.2 also has vastly higher performance than 8 bit AVR, and not just in the CPU speed.

Serial1 and Serial2 have hardware FIFOs and special high-res baud rate circuitry, which allows for use of much higher baud rates, up to 6 Mbit/sec.

The USB virtual serial is also very fast and efficient, so you can easily print quite a lot of info to the Arduino Serial Monitor without a huge impact to your program's speed, as happens when you transmit everything over ordinary serial at normal baud rates.
 
Thanks a lot Paul for the detailed information. That was exactly the kind of info I was looking for! :cool:
 
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