wip: spi interface.

1 files changed, 42 insertions, 0 deletions

diff --git a/main.c b/main.c
index f63f5ee..082d9d5 100644
--- a/main.c
+++ b/main.c
@@ -1,10 +1,52 @@
+#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
+
+static inline uint8_t read_reg(uint8_t reg)
+{
+	SPI_PORT &= ~(1 << SPI_SS);
+
+	SPDR = reg & 0x1F;
+	while (!(SPSR & (1 << SPIF)))
+		;
+
+	SPDR = 0xFF;
+	while (!(SPSR & (1 << SPIF)))
+		;
+
+	SPI_PORT |= (1 << SPI_SS);
+	return SPDR;
+}
+
+void radio_init(void)
+{
+	SPI_DDR |= (1 << SPI_SS) | (1 << SPI_SCK) | (1 << SPI_MOSI);
+	SPI_PORT |= (1 << SPI_SS);
+	SPCR |= (1 << SPE) | (1 << MSTR);
+}
+
 int main(void)
 {
 	uart_init();
+	radio_init();
+
+	for (int i = 0; i < 10; i++) {
+		uint8_t val = read_reg(0x00);
+
+		uart_write("CONFIG: ");
+		uart_write_char(val);
+		uart_write_char('\r');
+		uart_write_char('\n');
+	}
 
 	return 0;
 }