Teensy 3.2 only responds to reset button if USB is connected to serial terminal

[bboyes]

I'm seeing something odd. Running the example ILI9341Test for the touchscreen. All is well if USB serial is connected. If I press Teensy 3.2 reset button it restarts right away. But if there is just a power supply (I'm using the purple board to connect Teensy to the 2.8" touchscreen), or I power via USB from a power adapter, without a USB serial port open, Teensy won't restart with the reset button. It starts with a power-on, but can't be reset.

If I connect USB to a waiting serial monitor window then it starts up. Teensy appears to want to wait forever for a serial connection even if I don't want it to.

Same problem with or without this code in setup()
Serial.begin(115200);
while((!Serial) && (millis()<5000)); // wait until serial monitor is open or timeout
Serial.print(millis());
Serial.println(" ILI9341 Test! ");

On a related note, I notice that in the ILI9341Test as published there is no Serial.begin(), but Serial.print() seems to work anyway. If this is so, why is Serial.begin() needed?

Thanks
Bruce

 

[defragster]

The Teensy 3's ship with one "Program" Button. It generally takes the device offline until it is presented with USB programming commands. If on USB and the Teensy Loader can push code it will. When not on USB - or with no TeensyLoader actively seeing it or having code to upload it just goes offline.

Serial.begin() doesn't really do anything - and when the USB code is built into the uploaded sketch - it just works when connected. Perhaps it is just there for compatibility.

 

[bboyes]

Thanks. Yeah, I looked at the schematic again (should have done that before posting, but thought I remembered it working differently at some point in the past) and it is not a reset button, it's a program button as you point out. Duh on me. I'll have a go at hooking up a real reset and quit trying to use the program button the wrong way! I'm tempted to delete my original post but will leave it as it might help someone else avoid my confusion.