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#include <avr/io.h>
#include "rfm.h"
#define SS_PIN PB2
#define SS_DDR DDRB
#define SS_PORT PORTB
#define SCK_PIN PB5
#define MOSI_PIN PB3
#define MISO_PIN PB4
#define SPI_DDR DDRB
// RFM69 op modes
#define RX 0x10
#define TX 0x0C
#define SLEEP 0x00
#define STDBY 0x04
#define LISTEN_ON 0x40
static inline void spi_init(void)
{
SS_DDR |= (1 << SS_PIN);
SS_PORT |= (1 << SS_PIN);
SPI_DDR = (1 << MOSI_PIN) | (1 << SCK_PIN);
SPCR = (1 << SPE) | (1 << MSTR) | (1 << SPR0);
}
static inline uint8_t read_reg(uint8_t reg)
{
uint8_t data;
SS_PORT |= (1 << SS_PIN);
SPDR = addr | 0x7F;
while (!(SPSR & (1 << SPIF)))
;
data = SPDR;
SS_PORT &= ~(1 << SS_PIN);
return data;
}
static inline void write_reg(uint8_t reg, uint8_t val)
{
while (read_reg(reg) != val) {
SS_PORT |= (1 << SS_PIN);
SPDR = addr | 0x80;
while (!(SPSR & (1 << SPIF)))
;
SS_PORT &= ~(1 << SS_PIN);
}
}
static inline void set_mode(uint8_t mode)
{
write_reg(0x01, mode);
while (!read_reg(0x27))
;
}
void rfm_init(void)
{
spi_init();
set_mode(STDBY | LISTEN_ON);
// rx interrupt on DPIO0
write_reg(0x25, 0x40);
write_reg(0x26, 0x07);
// packet format: 8 bits + whitening + crc
write_reg(0x37, 0x52);
write_reg(0x38, 0x08);
// disable encryption
write_reg(0x3D, 0x02);
}
void rfm_sendto(uint8_t addr, uint8_t *data, uint8_t n)
{
uint8_t i;
set_mode(STDBY);
SS_PORT |= (1 << SS_PIN);
SPDR = 0x7F;
while (!(SPSR & (1 << SPIF)))
;
SPDR = addr;
while (!(SPSR & (1 << SPIF)))
;
for (i = 0; i < n; i++) {
SPDR = data[i];
while (!(SPSR & (1 << SPIF)))
;
}
SS_PORT &= ~(1 << SS_PIN);
set_mode(TX);
while (!((read_reg(0x28) >> 3) & 1))
;
}
void rfm_recvfrom(uint8_t addr, uint8_t *buf, uint8_t n)
{
uint8_t i;
SS_PORT |= (1 << SS_PIN);
for (i = 0; i < n && ((read_reg(0x28) >> 6) & 1); i++)
buf[i] = read_reg(0x00);
SS_PORT &= ~(1 << SS_PIN);
}
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