Yet Another Zero Overhead Abstraction Library For AVR.
## Specification
This document will outline the capabilities of this library and what features will be implemented.
The library is grouped into modules that each implement a zero overhead template-based abstraction for the underlying hardware of the AVR chip.
### IO
The IO module provides an abstraction for configuring the mode of a pin, or port, or virtual port. It provides an easy way of writing to, or reading from the underlying hardware.
#### Virtual port
Sometimes it is not possible to use a hardware port, because some pins are needed for their alternative functions. In this case it would be very convenient to group arbitrary pins into a virtual port that can then be used just like a regular port.
This will obviously incur some overhead compared to a hardware port, but not more than manually setting each pin.
### ADC
The ADC module provides an easy way to configure the mode of operation and will check that only pins with ADC can be used.
### UART
The UART module provides a general interface for serial communication which is decoupled from the actual backend driver. The backend driver might be UART0 (or UART1 if available), or it might be a software UART driver on chips (pins) that don't have hardware UART support.
The backend might also be interrupt driven and use some configurable receive/transmit buffer, or be blocking and not need any buffers. The buffers should only be allocated in interrupt driven mode and also be compile-time allocated.
### SPI
The SPI module, similar to UART, is decoupled from the backend. This allows a software backend to be used where no hardware SPI is supported.
### I2C
The I2C module is basically identical to SPI, just with a different protocol.
### Timers
The timers module allows the configuration of the hardware timers. Compile-time checks make sure that the requested time is actually achievable with the underlying hardware timer. The prescaler will be automatically calculated at compile-time based on the clock frequency, the hardware timer used and the time requested. The prescaler can also be specified directly.
#### PWM
The PWM mode of the hardware timer can also be used. Additionally, if PWM is needed on a pin that does not have hardware PWM support, a hardware timer can be used to implement software PWM.
