[moodlight.git] / rfm12.c

/* $Id: rfm12.c,v 1.1 2010/07/11 09:09:26 simimeie Exp $
 * Functions for communicating with the rfm12(b) module
 */

#include <avr/io.h>
#include "rfm12.h"

/* Unfortunately, the manufacturer documentation for chip and module is
 * almost unreadable crap.
 * This one is better: http://www.mikrocontroller.net/articles/RFM12
 */
/* Note: the signal is inverted, thus pulling this high DEselects the chip */
#define spi_ss_hi() { PORTC |= _BV(0); }
/* Consequently, this SELECTS the chip */
#define spi_ss_lo() { PORTC &= (uint8_t)~_BV(0); }

static void spi_sendbyte(uint8_t v) {
  /* Start transmission */
  SPDR = v;
  /* Wait for transmission complete */
  while ((SPSR & _BV(SPIF)) == 0) {
  }
}

static uint8_t spi_readbyte() {
  SPDR = 0x00; /* Dummy write */
  while ((SPSR & _BV(SPIF)) == 0) {
  }
  /* Return Data Register */
  return SPDR;
}

void rfm12_init(void) {
  /* Set MOSI, SCK and SS output, MISO input */
  DDRB |= _BV(3) | _BV(5);
  DDRC |= _BV(0);
  DDRB &= (uint8_t)~_BV(4);
  spi_ss_hi();
  /* Enable SPI, Master, set clock rate fck/4.
   * This works as long as our own clockrate is below 10 MHz - because
   * 2.5 MHz is the maximum the rfm12b can do. */
  SPCR |= _BV(SPE) | _BV(MSTR);
}
Commit	Line	Data
c95cbd3f	1	/* $Id: rfm12.c,v 1.1 2010/07/11 09:09:26 simimeie Exp $
	2	* Functions for communicating with the rfm12(b) module
	3	*/
	4
	5	#include <avr/io.h>
	6	#include "rfm12.h"
	7
	8	/* Unfortunately, the manufacturer documentation for chip and module is
	9	* almost unreadable crap.
	10	* This one is better: http://www.mikrocontroller.net/articles/RFM12
	11	*/
	12	/* Note: the signal is inverted, thus pulling this high DEselects the chip */
	13	#define spi_ss_hi() { PORTC \|= _BV(0); }
	14	/* Consequently, this SELECTS the chip */
	15	#define spi_ss_lo() { PORTC &= (uint8_t)~_BV(0); }
	16
	17	static void spi_sendbyte(uint8_t v) {
	18	/* Start transmission */
	19	SPDR = v;
	20	/* Wait for transmission complete */
	21	while ((SPSR & _BV(SPIF)) == 0) {
	22	}
	23	}
	24
	25	static uint8_t spi_readbyte() {
	26	SPDR = 0x00; /* Dummy write */
	27	while ((SPSR & _BV(SPIF)) == 0) {
	28	}
	29	/* Return Data Register */
	30	return SPDR;
	31	}
	32
	33	void rfm12_init(void) {
	34	/* Set MOSI, SCK and SS output, MISO input */
	35	DDRB \|= _BV(3) \| _BV(5);
	36	DDRC \|= _BV(0);
	37	DDRB &= (uint8_t)~_BV(4);
	38	spi_ss_hi();
	39	/* Enable SPI, Master, set clock rate fck/4.
	40	* This works as long as our own clockrate is below 10 MHz - because
	41	* 2.5 MHz is the maximum the rfm12b can do. */
	42	SPCR \|= _BV(SPE) \| _BV(MSTR);
	43	}