varpa: initial public commit

1 files changed, 106 insertions, 0 deletions

diff --git a/firmware/src/peripheral/spi.c b/firmware/src/peripheral/spi.c
new file mode 100644
index 0000000..884985d
--- /dev/null
+++ b/firmware/src/peripheral/spi.c
@@ -0,0 +1,106 @@
+/**
+ * 
+ * Author: Dylan Muller
+ * Copyright (c) 2025 
+ * All rights reserved.
+ * 
+ * - Commercial/IP use prohibited.
+ * - Attribution required.
+ * See License.txt
+ *
+ */
+
+#include "setup.h"
+
+#include "peripheral/spi.h"
+
+#include <stdio.h>
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <util/delay.h>
+
+#if SPI_MODE == 0
+    #define CPOL_VALUE 0
+    #define CPHA_VALUE 0
+#elif SPI_MODE == 1
+    #define CPOL_VALUE 0
+    #define CPHA_VALUE 1
+#elif SPI_MODE == 2
+    #define CPOL_VALUE 1
+    #define CPHA_VALUE 0
+#elif SPI_MODE == 3
+    #define CPOL_VALUE 1
+    #define CPHA_VALUE 1
+#else
+    #error "No valid SPI_MODE defined!"
+#endif
+
+#if SPI_DORD == 0
+    #define DORD_VALUE 0
+#elif SPI_DORD == 1
+    #define DORD_VALUE 1
+#else
+    #error "No valid SPI_DORD defined!"
+#endif
+
+static volatile uint8_t *spi_out;
+static volatile uint8_t *spi_in;
+static volatile size_t spi_len;
+static volatile uint8_t *spi_port;
+static volatile uint8_t spi_pin;
+
+void spi_init(void)
+{
+    DDRB |= (1 << DDB2) | (1 << DDB3) | (1 << DDB5);
+    
+    SPSR |= (SPI2X_VALUE << SPI2X);
+    SPCR |= (1 << SPIE) | (1 << SPE) | (DORD_VALUE << DORD) | (1 << MSTR)
+        | (CPOL_VALUE << CPOL) | (CPHA_VALUE << CPHA)
+        | (SPR1_VALUE << SPR1) | (SPR0_VALUE << SPR0);
+}
+
+bool spi_busy(void)
+{
+    return spi_len;
+}
+
+void spi_flush(void)
+{
+    while(spi_len);
+}
+
+void spi_start(
+    uint8_t *out,
+    uint8_t *in,
+    size_t len,
+    uint8_t *port,
+    uint8_t pin
+)
+{
+    spi_flush();
+    
+    spi_out = out;
+    spi_in = in;
+    spi_len = len;
+    spi_port = port;
+    spi_pin = pin;
+    
+    if(spi_port)
+        *spi_port &= ~(1 << spi_pin);
+    
+    SPDR = *spi_out++;
+}
+
+ISR(SPI_STC_vect)
+{
+    if(spi_in)
+    {
+        *spi_in++ = SPDR;
+    }
+    
+    if(--spi_len)
+        SPDR = *spi_out++;
+    else
+        if(spi_port)
+            *spi_port |= (1 << spi_pin);
+}