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#include <stdio.h>
#include <stdlib.h>
#include <avr/io.h>
#include <util/delay.h>
#include "uart.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
#define NRF_IRQ PD7
#define NRF_CE PB1
#define NRF_CE_DDR DDRB
#define NRF_CE_PORT PORTB
#define NRF_NOP 0xFF
#define NRF_R_REGISTER 0x1F
#define NRF_W_REGISTER 0x20
#define ADDRLEN 3
#define LEN(a) (sizeof(a) / sizeof(a[0]))
const char *bittab[16] = {
[ 0] = "0000", [ 1] = "0001", [ 2] = "0010", [ 3] = "0011",
[ 4] = "0100", [ 5] = "0101", [ 6] = "0110", [ 7] = "0111",
[ 8] = "1000", [ 9] = "1001", [10] = "1010", [11] = "1011",
[12] = "1100", [13] = "1101", [14] = "1110", [15] = "1111",
};
static inline uint8_t read_reg(uint8_t reg)
{
SPI_PORT &= ~(1 << SPI_SS);
SPDR = reg & NRF_R_REGISTER;
while (!(SPSR & (1 << SPIF)))
;
SPDR = NRF_NOP;
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 & 0x1F) | NRF_W_REGISTER;
while (!(SPSR & (1 << SPIF)))
;
SPDR = val;
while (!(SPSR & (1 << SPIF)))
;
SPI_PORT |= (1 << SPI_SS);
}
static inline void read_reg_bulk(uint8_t reg, uint8_t *data, uint8_t n)
{
uint8_t i;
SPI_PORT &= ~(1 << SPI_SS);
SPDR = reg & NRF_R_REGISTER;
while (!(SPSR & (1 << SPIF)))
;
for (i = 0; i < n; i++) {
SPDR = NRF_NOP;
while (!(SPSR & (1 << SPIF)))
;
data[i] = SPDR;
}
SPI_PORT |= (1 << SPI_SS);
}
static inline void write_reg_bulk(uint8_t reg, uint8_t *data, uint8_t n)
{
uint8_t i;
SPI_PORT &= ~(1 << SPI_SS);
SPDR = (reg & 0x1F) | NRF_W_REGISTER;
while (!(SPSR & (1 << SPIF)))
;
for (i = 0; i < n; i++) {
SPDR = data[i];
while (!(SPSR & (1 << SPIF)))
;
}
SPI_PORT |= (1 << SPI_SS);
}
static inline void print_config(void)
{
char s[22];
uint8_t i, rv, rxaddr[ADDRLEN];
uint8_t regs[] = {
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07
};
uart_write_line("NRF24L01 configuration:");
for (i = 0; i < LEN(regs); i++) {
rv = read_reg(i);
snprintf(s, LEN(s), "\t0x%02X: 0x%02X %s%s",
regs[i], rv, bittab[rv >> 4], bittab[rv & 0x0F]);
uart_write_line(s);
}
read_reg_bulk(0x0A, rxaddr, ADDRLEN);
snprintf(s, LEN(s), "\t0x0A: %d.%d.%d",
rxaddr[0], rxaddr[1], rxaddr[2]);
uart_write_line(s);
}
void radio_init(uint8_t rxaddr[ADDRLEN])
{
SPI_DDR |= (1 << SPI_SS) | (1 << SPI_SCK) | (1 << SPI_MOSI);
SPI_PORT |= (1 << SPI_SS);
SPCR |= (1 << SPE) | (1 << MSTR);
NRF_CE_DDR |= (1 << NRF_CE);
NRF_CE_PORT &= ~(1 << NRF_CE);
_delay_ms(110); /* power on reset delay */
write_reg(0x00, 0b00001100); /* set 2-byte CRC */
write_reg(0x01, 0b00111111); /* enable auto ack on all pipes */
write_reg(0x02, 0b00000001); /* enable rx address on pipe 0 */
write_reg(0x03, 0b00000001); /* set address width to 3 bytes */
write_reg(0x04, 0b00101111); /* 750uS retransmission delay, 15 tries */
write_reg(0x05, 0b01110011); /* use 2.515GHz channel */
write_reg(0x06, 0b00001110); /* set data rate to 1Mbps */
write_reg(0x07, 0b01110000); /* clear rx, tx, max_rt interrupts */
write_reg_bulk(0x0A, rxaddr, ADDRLEN);
}
int main(void)
{
uint8_t rxaddr[] = { 194, 178, 82 };
uart_init();
radio_init(rxaddr);
print_config();
return 0;
}
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