diff --git a/include/spi.h b/include/spi.h
new file mode 100644
index 0000000..5fa6aec
--- /dev/null
+++ b/include/spi.h
@@ -0,0 +1,12 @@
+#ifndef ROCKETLIB_SPI_H
+#define ROCKETLIB_SPI_H
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <xc.h>
+
+void spi1_init(void);
+uint8_t spi1_exchange(uint8_t data);
+void spi1_exchange_buffer(uint8_t *data, uint8_t data_len);
+
+#endif
diff --git a/pic18f26k83/spi.c b/pic18f26k83/spi.c
new file mode 100644
index 0000000..0081f82
--- /dev/null
+++ b/pic18f26k83/spi.c
@@ -0,0 +1,54 @@
+#include <stdbool.h>
+#include <xc.h>
+
+#include "spi.h"
+
+void spi1_init(void) {
+    TRISC3 = 0;
+
+    SPI1CLKbits.CLKSEL = 0;
+    SPI1BAUD = 0x22;
+
+    SPI1CON0bits.MST = 1; // set mode to master
+    SPI1CON0bits.BMODE = 1; // sets bit mode to constant width
+    SPI1CON1bits.CKP = 0; // idle state for clk is low
+    SPI1CON1bits.SSP = 1; // make cs active low
+    SPI1CON1bits.SDOP = 0;
+    SPI1CON1bits.SDIP = 0;
+
+    SPI1CON1bits.CKE = 1; // change data on falling edge
+
+    SPI1CON2bits.TXR = 0; // no transmit required for transfer
+    SPI1CON2bits.RXR = 1; // receive data in FIFO
+    SPI1TWIDTH = 0; // 8 bits
+    // Enable SPI
+    PIE2bits.SPI1RXIE = 1; // enable interrupts so we know when device has ACK
+    SPI1CON0bits.EN = 1; // enable SPI
+}
+
+/**/
+uint8_t spi1_exchange(uint8_t data) {
+    INTCON0bits.GIE = 0;
+    SPI1CON2bits.TXR = 0;
+    SPI1CON2bits.RXR = 1;
+    SPI1TCNT = 1;
+    SPI1TXB = data; /*if we're sending data, send it. if we're recieving, this is 0 (unless you
+   // initialized bad), but makes sure we output a clock*/
+    while (!PIR2bits.SPI1RXIF) {
+    } // wait until receive buffer is not empty?? (basically until theres a clock)
+    data = SPI1RXB;
+    INTCON0bits.GIE = 1;
+    return data; // reading should remove top most byte
+}
+
+void spi1_exchange_buffer(uint8_t *data, uint8_t data_len) {
+    // set data length
+    SPI1TCNTL = data_len;
+    SPI1TCNTH = 0;
+    // uint8_t *block = data;
+    while (data_len) {
+        *data = spi1_exchange(*data); // sends pointer, so data gets shoved into array
+        data++; // increment array
+        data_len--;
+    }
+}