# yazoalfa

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.

## Goals

- IO
    - [x] Interface for io-pins
    - [x] Interface for io-ports
    - [x] Interface for mapping io-pins onto virtual io-ports, where the pins do not have to be located on the same hardware port
    - [x] Provide an example showcasing the usage and possibilities
- ADC
    - [ ] Support all hardware provided configuration options
    - [ ] Compile-time check for correct hardware configuration
    - [ ] Provide an example showcasing the usage and possibilities
- UART
    - [x] Separation of interface and backend-driver
    - [x] Support common usage with easy extendability
    - [x] Compile-time check for correct hardware configuration
    - [x] Blocking hardware backend
    - [x] Interrupt driven hardware backend
    - [x] Type-safe convenience functions for writing basic data types
    - [x] Provide an example showcasing the usage and possibilities
- SPI
    - [x] Separation of interface and backend-driver
    - [x] Support all hardware provided configuration options
    - [x] Compile-time check for correct hardware configuration
    - [x] Provide an example showcasing the usage and possibilities
- I2C
    - [x] Separation of interface and backend-driver
    - [x] Support common usage with easy extendability
    - [x] Compile-time check for correct hardware configuration
    - [x] Provide an example showcasing the usage and possibilities
- Timers
    - [ ] Support all hardware provided configuration options
    - PWM
        - [ ] Compile-time check for correct hardware configuration
        - [ ] Software PWM on pins that don't have hardware PWM support
    - [ ] Provide an example showcasing the usage and possibilities
- General
    - [ ] Support for most common AVR chips (ATmega8, ATmega328, ATtiny85, ...)