simplified example & added readme

pull/1/head
Ondřej Hruška 9 years ago
parent 595a57c30c
commit ce2ca2d4e1
  1. 48
      README.md
  2. 16
      lib/usart.h
  3. 16
      main.c

@ -1,2 +1,46 @@
# avr-c-boilerplate
Basic boilerplate for programming AVR (arduino) in C.
# AVR C Builerplate
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 software 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`.
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`.
The Makefile should take care of everything for you, this is the only modification
you should have to do.

@ -14,6 +14,22 @@
#include <stdbool.h>
#include <stdint.h>
/* USART BAUD RATE REGISTER values at 16 MHz */
enum {
BAUD_9600 = 103,
BAUD_14400 = 68,
BAUD_19200 = 51,
BAUD_28800 = 34,
BAUD_38400 = 25,
BAUD_57600 = 16,
BAUD_76800 = 12,
BAUD_115200 = 8,
BAUD_250k = 3,
BAUD_500k = 1,
BAUD_1M = 0,
};
/** Init UART with a UBRR value */
void usart_init(uint16_t ubrr);

@ -10,7 +10,6 @@
#include "lib/iopins.h"
#include "lib/usart.h"
void main() __attribute__ ((noreturn));
// Pins
#define LED 13
@ -19,6 +18,7 @@ void main() __attribute__ ((noreturn));
// UART receive handler
ISR(USART_RX_vect)
{
// "ECHO" function:
uint8_t b = usart_rx();
usart_tx(b); // send back
}
@ -26,7 +26,7 @@ ISR(USART_RX_vect)
void main()
{
usart_init(8); // set usart @ 115200 (8 is a UBRR value)
usart_init(BAUD_9600);
usart_rx_isr_enable(true); // enable RX interrupt handler
// configure pins
@ -36,17 +36,9 @@ void main()
sei();
while (1) {
// This string is in the program memory
// PSTR is a special macro that puts it there.
// That means it does not waste ram space, but
// needs special treatment when being read.
// (avr-gcc is a bit dumb in this)
usart_puts_P( PSTR("Hello World\r\n") ); // Print a string to USART
usart_puts("Hello World!\r\n");
// This one is copied to RAM before being printed = bad.
usart_puts("Wastin' RAM!\r\n");
pin_toggle(13);
pin_toggle(13); // blink the LED
_delay_ms(500);
}

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