From 4c9558852a982e25ff6c5cb7b7febe6abdb3a77f Mon Sep 17 00:00:00 2001
From: Nero <41307858+nero@users.noreply.github.com>
Date: Wed, 13 Nov 2019 22:40:02 +0000
Subject: [PATCH] Add SPI driver

---
 drivers/spi.c | 23 +++++++++++++++++++++++
 drivers/spi.h |  4 ++++
 2 files changed, 27 insertions(+)
 create mode 100644 drivers/spi.c
 create mode 100644 drivers/spi.h

diff --git a/drivers/spi.c b/drivers/spi.c
new file mode 100644
index 0000000..bb59a03
--- /dev/null
+++ b/drivers/spi.c
@@ -0,0 +1,23 @@
+#include "spi.h"
+#include <avr/io.h>
+
+uint8_t spi_init(uint8_t spcr) {
+  PORTB |= (1 << 5); // set SCK hi
+  DDRB |= (1 << 5); // set SCK as output
+  DDRB &= ~(1 << 4); // set MISO as input
+  DDRB |= (1 << 3); // set MOSI as output
+  DDRB |= (1 << 2); // SS must be output for Master mode to work
+
+  SPCR = spcr | SPE;
+  return(SPSR);
+}
+
+uint8_t spi_transfer(uint8_t in) {
+  uint8_t v;
+  SPDR = in;
+  // wait for transfer to complete
+  while(! (SPSR & (1<<SPIF)) ) {};
+  v = SPDR;
+  return(v);
+}
+
diff --git a/drivers/spi.h b/drivers/spi.h
new file mode 100644
index 0000000..eb77636
--- /dev/null
+++ b/drivers/spi.h
@@ -0,0 +1,4 @@
+#include <stdint.h>
+
+uint8_t spi_init(uint8_t spcr);
+uint8_t spi_transfer(uint8_t in);