completely redid PWM: Now calculate 'microprograms', i.e. pairs of

[moodlight.git] / rfm12.c

/* $Id: rfm12.c,v 1.2 2010/07/24 20:55:48 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); }

/* write and (at the same time) read a word from RFM12.
 * The module uses 16 bit commands and replies that are
 * synchronous to the command - except for the status read.
 * Note: This does not handle chip select! */
static uint16_t rfm12_spi_wrword(uint16_t v) {
  uint16_t res;
  /* Start transmission */
  SPDR = v >> 8;
  /* Wait for transmission complete */
  while ((SPSR & _BV(SPIF)) == 0) {
  }
  res = (uint16_t)(SPDR) << 8;
  SPDR = v & 0xff;
  /* Wait for transmission complete */
  while ((SPSR & _BV(SPIF)) == 0) {
  }
  res |= SPDR & 0xff;
  return res;
}

void rfm12_sendcommand(uint16_t cmd) {
  spi_ss_lo();
  rfm12_spi_wrword(cmd);
  spi_ss_hi();
}

uint32_t rfm12_readstatus(void) {
  uint32_t res;
  spi_ss_lo();
  res = (uint32_t)rfm12_spi_wrword(0x0000) << 16;
  res |= rfm12_spi_wrword(0x0000);
  spi_ss_hi();
  return res;
}

void rfm12_init(void) {
  /* Set MOSI, SCK and SS output, MISO input */
  /* Frickel Alert: Also set PB2 output. It is not used, but noise on the
   * pin could reset our SPI mode to slave (!!!) if it is left as input. */
  DDRB |= _BV(3) | _BV(5) | _BV(2);
  DDRC |= _BV(0);
  DDRB &= (uint8_t)~_BV(4);
  spi_ss_hi();
#if (CPUFREQ <= 10000000UL)
  /* 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);
#else
  /* For higher clock rates set fck/16. */
  SPCR |= _BV(SPE) | _BV(MSTR) | _BV(SPR0);
#endif /* CPUFREQ */
  /* Now send some initialization commands. */
  /* Mostly taken over from http://www.joachim-neu.de/post/70/rfm12b-868/
   * Seems to be mostly black magic anyways. */
  rfm12_sendcommand(0x80E7); /* EL, EF, 868band, 12.0pF */
  rfm12_sendcommand(0x8219); /* !er, !ebb, !ET, ES, EX, !eb, !ew, DC */
  /* Frequency setting: 0xAnnn; the 12 nnn-bits of value are
   * calculated like this:   v = ((freq / 20) - 43) * 4000
   */
  rfm12_sendcommand(0xA7BC); /* 869,900 MHz */
  rfm12_sendcommand(0xC647); /* 4.8kbps FIXME? */
  rfm12_sendcommand(0x94C0); /* VDI, FAST, 67kHz, 0dBm, -103dBm */
  rfm12_sendcommand(0xC2AC); /* AL, !ml, DIG, DQD4 */
  rfm12_sendcommand(0xCA81);//FIFO8,SYNC,!ff,DR
  rfm12_sendcommand(0xCED4);//SYNC=2DD4;
  rfm12_sendcommand(0xC483);//@PWR,NO RSTRIC,!st,!fi,OE,EN
  rfm12_sendcommand(0x9820);// !mp,45kHz,MAX OUT*/
  rfm12_sendcommand(0xCC77);//OB1,OB0, LPX,!ddy,DDIT,BW0
  rfm12_sendcommand(0xE000);//NOT USE
  rfm12_sendcommand(0xC800);//NOT USE
  rfm12_sendcommand(0xC040);//1.66MHz,2.2V
}