wip: spi interface.

3 files changed, 53 insertions, 6 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;
 }
diff --git a/uart.c b/uart.c
index b2a1b59..d3012af 100644
--- a/uart.c
+++ b/uart.c
@@ -16,18 +16,22 @@ void uart_init(void)
 	UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);
 }
 
-void uart_write(char c)
+void uart_write_char(char c)
 {
 	while (!(UCSR0A & (1 << UDRE0)))
 		;
 	UDR0 = c;
 }
 
-void uart_write_line(const char *s)
+void uart_write(const char *s)
 {
 	for (; *s; s++)
-		uart_write(*s);
+		uart_write_char(*s);
+}
 
-	uart_write('\r');
-	uart_write('\n');
+void uart_write_line(const char *s)
+{
+	uart_write(s);
+	uart_write_char('\r');
+	uart_write_char('\n');
 }
diff --git a/uart.h b/uart.h
index 81db74b..854cd14 100644
--- a/uart.h
+++ b/uart.h
@@ -2,7 +2,8 @@
 #define UART_H
 
 void uart_init(void);
-void uart_write(char c);
+void uart_write_char(char c);
+void uart_write(const char *s);
 void uart_write_line(const char *s);
 
 #endif /* UART_H */