make SPI work by understanding how it actually works

git-svn-id: https://svn.spreadspace.org/mur.sat@419 7de4ea59-55d0-425e-a1af-a3118ea81d4c

1 files changed, 6 insertions, 8 deletions

diff --git a/software/hhd70dongle/spi.c b/software/hhd70dongle/spi.c
index e676fbf..85831d1 100644
--- a/software/hhd70dongle/spi.c
+++ b/software/hhd70dongle/spi.c
@@ -69,26 +69,24 @@ void spi_cs_disable(void)
     PORTB |= (1<<CS);
 }
 
-//synchronous
 void spi_write_byte(char byte)
 {
     SPDR = byte;					//Load byte to Data register
     while(!(SPSR & (1<<SPIF))); 	// Wait for transmission complete
 }
 
-//~ void spi_write(char* data, unsigned int len)
-//~ {
-    //~ for (unsigned int c=0; c<len; c++)
-        //~ spi_write_byte(data[c]);
-//~ }
-
-//MSB first
 char spi_read_byte(void)
 {
     while(SPI_PINB_REG & (1<<MISO)); /* wait for CC1101 to get ready... */
     return SPSR;
 }
 
+char spi_exchange_byte(char byte)
+{
+    spi_write_byte(byte);
+    return spi_read_byte();
+}
+
 //~ void spi_read(unsigned int maxlen, char *data, unsigned int *len)
 //~ {
     //~ PORTB |= (1<<CS);