# AVR C Boilerplate
This is a basic boilerplate for programming AVRs in C.
The project aims to make programming Arduinos in C fun by
providing support for basic functionality like GPIO and USART,
so you can start developing without having the datasheet open
all the time.
It is intended for **ATmega328P** (the chip in Arduinos),
but can be easily adapted to other parts.
## Requirements
Before you can start coding, you need to install a few software packages:
- `avrdude` - the flash tool
- `avr-gcc` - compiler
- `avr-libc` - libc implementation for AVR
- `avr-binutils` - utils for manipulating AVR binaries
- `make` - to run the Makefile
There's a good chance you already have `make` , the rest should be in your
distribution's repos.
If you're on Arch:
```
# pacman -S base-devel avr-gcc avr-binutils avr-libc avrdude
```
If you're on Mac, you should be able to pull the stuff with *brew* .
## Getting started
The provided `main.c` is a good starting point - it contains some simple demo code.
You can compile it with `make` and flash with `make flash` .
### Before you can flash
First, check that the `avrdude` options in the file are correct for your system - especially
the device and speed.
```ini
# AVRDUDE settings
PROG_BAUD = 57600
PROG_DEV = /dev/ttyUSB0
PROG_TYPE = arduino
# Build the final AVRDUDE arguments
PROG_ARGS = -c $(PROG_TYPE) -p $(MCU) -b $(PROG_BAUD) -P $(PROG_DEV)
```
- Adjust `PROG_DEV` to the device your board is connected to. On Linux it's usually
`/dev/ttyUSB0` , but it can also be `/dev/ttyACM0` or something else. On Mac, it'll be
`/dev/cu.xxx` . On Windows it's some `COMx` .< br >
Linux and Mac users can use `ls /dev` to see their devices. Windows users will find
this in their Device Manager.
- You may also adjust the baudrate (`PROG_BAUD`). Some boards need `115200` .
**TIP:** You can look what the Arduino IDE is using - it's running avrdude too.
### Adding new files
- If you *add a new C file* to the project, add an entry for it's `.o` (object file,
created by the compiler before linking) to the `OBJS` list in the Makefile.
- Similarly, if you *add a new folder with header files* , add it to `INCL_DIRS` .
- In case you need `printf` (or `printf` with floats), enable the appropriate LD_FLAGS
in the Makefile (it's well commented). Code size will - obviously - grow quite a bit.
## Notes
### USART
Note that if you are using an **Arduino Uno** , USART work a little different; If you set the baudrate to `57600` for example, the baudrate you'll have to listen for in your terminal will become double the rate you've set in the code, so that's `115200` . This is because the Uno runs on `Asynchronous Double Speed Mode` by default.
