The error message was:
wiring.c.o [...]: multiple definition of `__vector_5'
Glove_heater_v1.ino.cpp.o [...]: first defined here
__vector_5 is TIMER0_OVF_vect. So you have one definition of this
ISR in your sketch, and another one in wiring.c. This wiring.c is part
of the Arduino core. As KIIV puts it in a comment, it uses
TIMER0_OVF_vect for ...
The ATTiny chips commonly used in Arduino-like boards, such as the Adafruit Trinket or the Digispark USB will usually have a bootloader which runs before your own code. The bootloader checks for a certain state on the USB port of the board, to see if something is waiting to write a new program to the chip.
The bootloader accepts new code from the host ...
You can just normally use all pins except for the reset pin (pin 0). When you want to program the Attiny, you just connect the programmer. It will reset the Attiny through the reset pin and put it into ISP programming mode. At that point your code hasn't run.
Note: If you want to program the Attiny while it still sits in its circuit, you have to be careful, ...
The only explanation I have is, that the Software serial switch off the interrupts globally when it operates (print). If interrupts are locked when the timer completes, you loose a tick. It does not explain the different behavior of the four value pairs, but there are some issues reported in a german forum. They did not find an answer, but the assumed it ...
Can I use a ATtiny85 board (eg Digispark) as a USB CDC device?
If I have got this right, to be able to communicate with a USB serial device you need to have USB CDC support and if you want it to fake a keyboard/mouse you need HID.
The Digispark have a CDC library https://digistump.com/wiki/digispark/tutorials/digicdc
But it has its limitations, take ...
You mean that the STK500 v2 programmer uses an emulated serial port
rather than direct USB? Then I guess there is a bug in the Arduino IDE.
The file programmers.txt contains the following lines
describing the programmer:
I would say you have to select the Arduino as ISP Programmer. Not the mkII ISP. Perhaps the attiny board library can handle connection to attiny dev boards over usb if you use the standard programmer. But that's just a very very rough guess. But selecting the Arduino as ISP is a requirement.
No you can not use the Arduino as ISP if you use an STK500 ...