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#include <avr/io.h>
#include "radio.h"
#define SPI_SS PB2
#define SPI_SCK PB5
#define SPI_MISO PB4
#define SPI_MOSI PB3
#define SPI_DDR DDRB
#define SPI_PORT PORTB
static inline uint8_t read_reg(uint8_t reg)
{
SPI_PORT &= ~(1 << SPI_SS);
SPDR = reg & 0x7F;
while (!(SPSR & (1 << SPIF)))
;
SPDR = 0;
while (!(SPSR & (1 << SPIF)))
;
SPI_PORT |= (1 << SPI_SS);
return SPDR;
}
static inline void write_reg(uint8_t reg, uint8_t val)
{
SPI_PORT &= ~(1 << SPI_SS);
SPDR = reg | 0x80;
while (!(SPSR & (1 << SPIF)))
;
SPDR = val;
while (!(SPSR & (1 << SPIF)))
;
SPI_PORT |= (1 << SPI_SS);
}
void radio_send(const char *data, uint8_t n)
{
uint8_t i;
// STDBY + ListenAbort mode
write_reg(0x01, 0x04);
while ((read_reg(0x27) >> 7) != 1)
;
SPI_PORT &= ~(1 << SPI_SS);
SPDR = 0x00 | 0x80;
while (!(SPSR & (1 << SPIF)))
;
for (i = 0; i < n; i++) {
SPDR = data[i];
while (!(SPSR & (1 << SPIF)))
;
}
SPI_PORT |= (1 << SPI_SS);
write_reg(0x01, 0x0C);
while (!read_reg(0x28))
;
write_reg(0x01, 0x04);
while ((read_reg(0x27) >> 7) != 1)
;
// enable ListenOn in STDBY mode
write_reg(0x01, (read_reg(0x01) | 0x40));
}
uint8_t radio_recv(char *buf, uint8_t n)
{
uint8_t i;
i = 0;
if ((read_reg(0x28) & 0x04))
{
write_reg(0x01, 0x04);
while ((read_reg(0x27) >> 7) != 1)
;
SPI_PORT &= ~(1 << SPI_SS);
SPDR = 0x00 | 0x7F;
while (!(SPSR & (1 << SPIF)))
;
while (i < n) {
SPDR = 0;
while (!(SPSR & (1 << SPIF)))
;
buf[i++] = SPDR;
}
SPI_PORT |= (1 << SPI_SS);
}
return i;
}
void radio_init(struct radio_cfg *cfg)
{
SPI_DDR |= (1 << SPI_SS) | (1 << SPI_SCK) | (1 << SPI_MOSI);
SPI_PORT |= (1 << SPI_SS);
SPCR |= (1 << SPE) | (1 << MSTR);
if (cfg->payload_len > 0)
write_reg(0x38, cfg->payload_len);
}
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