Will pressing the reset/program button by itself erase the chip?

[scswift]

Will pressing the reset button on the Teensy 3.1 wipe the chip immediately, or, will it, as I hope, simply put the helper chip into a mode where it waits for confirmation from the USB port that a new program is ready to be uploaded before it wipes the chip?

I intend to embed these things in kits I sell, and I don't want the end user pushing the button and wiping it by accident!

 

[drg]

No, pressing the button won't erase the chip. It just runs the boot loader to connect over USB to the Teensy Loader app. It won't erase unless the Teensy Loader app commands a chip erase. Pressing the button will, however, halt your program until you power-cycle or use an external button on the reset pin. It's not really a reset button, but a button to launch the boot loader firmware.

 

[scswift]

Okay, that's good.

Is there any delay before the application is run on these boards when you apply power? I recently purchased an Adafruit Micro and was dismayed to find there was a 2-3 second pause every time I turned the board on. (I'm aware I can circumvent it by programming he boards via the ISP header but I'd hoped to avoid that.)

I'm guessing there isn't because of that additional chip. I assume it monitors the USB but the main chip will run the program immediately on power up and only reset if that main chip decides to pull the program line low.

 

[PaulStoffregen]

Is there any delay before the application is run on these boards when you apply power?

Only a very brief delay while the hardware detects the power supply achieving a stable voltage and some initialization the hardware does before it starts executing software. You can read about the chip's startup sequence in extreme detail in the chip's reference manual.

I recently purchased an Adafruit Micro and was dismayed to find there was a 2-3 second pause every time I turned the board on.

Definitely not anything like that. The bootloader does NOT run at powerup. The Arduino folks design their boards that way, but I do not make Teensy like that. Quick startup is important.

I assume it monitors the USB but the main chip will run the program immediately on power up and only reset if that main chip decides to pull the program line low.

More or less, yes. The MK20 chip runs your program as soon as possible, limited only by the chip's own internal bootup process.

How the 2 chips work together actually involves quite a number of complex details. Trust me, I've been doing this stuff a lot longer than the Arduino guys and I care deeply about performance. It really is designed to give you the best performance these chips can offer.

From the tone and content of your questions, I'm guessing you haven't actually used a Teensy yet? If not, you really ought to just give it a try. I believe you'll like it. Most people who's used Arduino instantly notice how much quicker Teensy uploads code. It definitely boots into your code at startup, rather than delaying in a bootloader like most official Arduino boards do.

 

[scswift]

I purchased one, and I've got it on a breadboard already with some other components but I haven't had a chance to power it up yet. I like what I've seen so far though.