Gpio Pins - adafruit learning system Trinket Introduction Manual

suggested. This input is reverse-polarity protected.
USB+ is the USB + Output pin. If you want to use the USB 5V power for something,
like charging a battery, or if you need more than 150mA of current (this pin can supply
500mA+ from USB ports) or to detect when the Trinket is plugged into USB, this pin
will have 5V power on it if and only if its plugged into something via the mini B
connector
GND is the common ground pin, used for logic and power. It is connected to the USB
ground and the power regulator, etc. This is the pin you'll want to use for any and all
ground connections

GPIO Pins

Next we will cover the 5 GPIO (General Purpose Input Ouput) pins! For reference you may
want to also check out the datasheet-reference above for the core ATtiny85 pin
All the GPIO pins can be used as digital inputs, digital outputs, for LEDs, buttons and switches
etc. They can provide up to 20mA of current. Don't connect a motor or other high-power
component directly to the pins!
on/off (http://adafru.it/aUD)
On a 3V Trinket, the GPIO are 3.3V output level, and should not be used with 5V inputs. On a
5V Trinket, the GPIO are 5V output level, and can be used with 3V inputs but may damage
electronic devices that are 3V input only!
The first 3 pins are completely 'free' pins, they are not used by the USB connection so you
never have to worry about the USB interface interfering with them when programming
GPIO #0 - this is connected to PB0 on the ATtiny85. This pin can be used as a PWM
output, and is also used for I2C data, and SPI data input.
GPIO #1 - this is connected to PB1 on the ATtiny85. This pin can be used as a PWM
output, and is also used for SPI data output. This pin is also connected to the onboard
LED (like pin 13 on a regular Arduino).
GPIO #2 - this is connected to PB2 on the ATtiny85. This pin can be used as an
analog input (known as Analo g A1), and is also used for I2C clock and SPI clock.
The next 2 pins are also used for USB programming. That means that when the Trinket is
connected to a computer and in bootloader mode or in the middle of uploading a new
program, they are used for sending data to/from the computer! It's possible to share these
pins if you are careful. The best use of these pins is as o utputs to things like LEDs , or
inputs to things like buttons and just make sure not to press the buttons while connected
to USB. We didn't want to keep these pins off the board but we strongly recommend not
using them unless you're sure you need them since you might have to disconnect any
connections to reprogram the Trinket!
GPIO #3 - this is connected to PB3 on the Attiny85. This pin is used for USB
programming, but its also an analog input known as Analo g A3
GPIO #4 - this is connected to PB4 on the Attiny85. this pin is used for USB
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Instead, use a transistor to power the DC motor
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