diff --git a/firmware/common/max5864.c b/firmware/common/max5864.c
new file mode 100644
index 00000000..711bdbbd
--- /dev/null
+++ b/firmware/common/max5864.c
@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2012 Jared Boone <jared@sharebrained.com>
+ *
+ * This file is part of HackRF.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include <stdint.h>
+
+#include <libopencm3/lpc43xx/gpio.h>
+#include <libopencm3/lpc43xx/ssp.h>
+
+#include "hackrf_core.h"
+#include "max5864.h"
+
+void max5864_spi_write(uint_fast8_t value) {
+	gpio_clear(PORT_AD_CS, PIN_AD_CS);
+	ssp_write(SSP1_NUM, value);
+	gpio_set(PORT_AD_CS, PIN_AD_CS);
+}
+
+/* Set MAX5864 operation mode to "Shutdown":
+ *   REF: off
+ *   CLK: off
+ *   ADCs: off (bus is tri-stated)
+ *   DACs: off (set input bus to zero or OVdd)
+ */
+void max5864_shutdown()
+{
+	max5864_spi_write(0x00);
+}
+
+/* Set MAX5864 operation mode to "Standby":
+ *   REF: on
+ *   CLK: off?
+ *   ADCs: off (bus is tri-stated)
+ *   DACs: off (set input bus to zero or OVdd)
+ */
+void max5864_standby()
+{
+	max5864_spi_write(0x05);
+}
+
+/* Set MAX5864 operation mode to "Idle":
+ *   REF: on
+ *   CLK: on
+ *   ADCs: off (bus is tri-stated)
+ *   DACs: off (set input bus to zero or OVdd)
+ */
+void max5864_idle()
+{
+	max5864_spi_write(0x01);
+}
+
+/* Set MAX5864 operation mode to "Rx":
+ *   REF: on
+ *   CLK: on
+ *   ADCs: on
+ *   DACs: off (set input bus to zero or OVdd)
+ */
+void max5864_rx()
+{
+	max5864_spi_write(0x02);
+}
+
+/* Set MAX5864 operation mode to "Tx":
+ *   REF: on
+ *   CLK: on
+ *   ADCs: off (bus is tri-stated)
+ *   DACs: on
+ */
+void max5864_tx()
+{
+	max5864_spi_write(0x03);
+}
+
+/* Set MAX5864 operation mode to "Xcvr":
+ *   REF: on
+ *   CLK: on
+ *   ADCs: on
+ *   DACs: on
+ */
+void max5864_xcvr()
+{
+	max5864_spi_write(0x04);
+}
diff --git a/firmware/common/max5864.h b/firmware/common/max5864.h
new file mode 100644
index 00000000..0af59415
--- /dev/null
+++ b/firmware/common/max5864.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2012 Jared Boone <jared@sharebrained.com>
+ *
+ * This file is part of HackRF.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef __MAX5864_H
+#define __MAX5864_H
+
+void max5864_shutdown();
+void max5864_standby();
+void max5864_idle();
+void max5864_rx();
+void max5864_tx();
+void max5864_xcvr();
+
+#endif // __MAX5864_H