diff --git a/flight/PiOS/Common/pios_opahrs_v0.c b/flight/PiOS/Common/pios_opahrs_v0.c
new file mode 100644
index 000000000..507fcee2d
--- /dev/null
+++ b/flight/PiOS/Common/pios_opahrs_v0.c
@@ -0,0 +1,262 @@
+/**
+ ******************************************************************************
+ * @addtogroup PIOS PIOS Core hardware abstraction layer
+ * @{
+ * @addtogroup PIOS_OPAHRS OPAHRS Functions
+ * @brief HAL code to interface to the OpenPilot AHRS module's bootloader
+ * @{
+ *
+ * @file       pios_opahrs_download.c  
+ * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
+ * @brief      Hardware commands to communicate with the AHRS bootloader
+ * @see        The GNU Public License (GPL) Version 3
+ * 
+ *****************************************************************************/
+/* 
+ * 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 3 of the License, 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; if not, write to the Free Software Foundation, Inc., 
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+/* Project Includes */
+#include "pios.h"
+
+#if defined(PIOS_INCLUDE_OPAHRS)
+
+#include "pios_opahrs_proto.h"
+#include "pios_opahrs.h"
+
+static enum opahrs_result opahrs_msg_v0_send_req (const struct opahrs_msg_v0 * req)
+{
+	int32_t rc;
+	struct opahrs_msg_v0 link_rx;
+
+	for (uint8_t retries = 0; retries < 20; retries++) {
+		struct opahrs_msg_v0 * rsp = &link_rx;
+
+		if ((rc = opahrs_msg_txrx((const uint8_t *)req, (uint8_t *)rsp, sizeof(*rsp))) < 0) {
+			return OPAHRS_RESULT_FAILED;
+		}
+
+		/* Make sure we got a sane response by checking the magic */
+		if ((rsp->head.magic != OPAHRS_MSG_MAGIC_HEAD) ||
+				(rsp->tail.magic != OPAHRS_MSG_MAGIC_TAIL)) {
+			return OPAHRS_RESULT_FAILED;
+		}
+
+		switch (rsp->head.type) {
+		case OPAHRS_MSG_TYPE_LINK:
+			switch (rsp->payload.link.state) {
+			case OPAHRS_MSG_LINK_STATE_BUSY:
+			case OPAHRS_MSG_LINK_STATE_INACTIVE:
+				/* Wait for a small delay and retry */
+#ifdef PIOS_INCLUDE_FREERTOS
+				vTaskDelay(20 / portTICK_RATE_MS);
+#else
+				PIOS_DELAY_WaitmS(20);
+#endif
+				continue;
+			case OPAHRS_MSG_LINK_STATE_READY:
+				/* Peer was ready when we Tx'd so they have now Rx'd our message */
+				return OPAHRS_RESULT_OK;
+			}
+			break;
+		case OPAHRS_MSG_TYPE_USER_V0:
+		case OPAHRS_MSG_TYPE_USER_V1:
+			/* Wait for a small delay and retry */
+#ifdef PIOS_INCLUDE_FREERTOS
+			vTaskDelay(50 / portTICK_RATE_MS);
+#else
+			PIOS_DELAY_WaitmS(50);
+#endif
+			continue;
+		}
+	}
+
+	return OPAHRS_RESULT_TIMEOUT;
+}
+
+static enum opahrs_result opahrs_msg_v0_recv_rsp (enum opahrs_msg_v0_tag tag, struct opahrs_msg_v0 * rsp)
+{
+	struct opahrs_msg_v0 link_tx;
+
+	opahrs_msg_v0_init_link_tx(&link_tx, OPAHRS_MSG_LINK_TAG_NOP);
+
+	for (uint8_t retries = 0; retries < 20; retries++) {
+		if (opahrs_msg_txrx((const uint8_t *)&link_tx, (uint8_t *)rsp, sizeof(*rsp)) < 0) {
+			return OPAHRS_RESULT_FAILED;
+		}
+
+		/* Make sure we got a sane response by checking the magic */
+		if ((rsp->head.magic != OPAHRS_MSG_MAGIC_HEAD) ||
+				(rsp->tail.magic != OPAHRS_MSG_MAGIC_TAIL)) {
+			return OPAHRS_RESULT_FAILED;
+		}
+
+		switch (rsp->head.type) {
+		case OPAHRS_MSG_TYPE_LINK:
+			switch (rsp->payload.link.state) {
+			case OPAHRS_MSG_LINK_STATE_BUSY:
+				/* Wait for a small delay and retry */
+#ifdef PIOS_INCLUDE_FREERTOS
+				vTaskDelay(20 / portTICK_RATE_MS);
+#else
+				PIOS_DELAY_WaitmS(20);
+#endif
+				continue;
+			case OPAHRS_MSG_LINK_STATE_INACTIVE:
+			case OPAHRS_MSG_LINK_STATE_READY:
+				/* somehow, we've missed our response */
+				return OPAHRS_RESULT_FAILED;
+			}
+			break;
+		case OPAHRS_MSG_TYPE_USER_V0:
+			if (rsp->payload.user.t == tag) {
+				return OPAHRS_RESULT_OK;
+			} else {
+				return OPAHRS_RESULT_FAILED;
+			}
+			break;
+		case OPAHRS_MSG_TYPE_USER_V1:
+			/* This isn't the type we expected */
+			return OPAHRS_RESULT_FAILED;
+			break;
+		}
+	}
+
+	return OPAHRS_RESULT_TIMEOUT;
+}
+
+static enum opahrs_result PIOS_OPAHRS_v0_simple_req (enum opahrs_msg_v0_tag req_type, struct opahrs_msg_v0 * rsp, struct opahrs_msg_v0_tag rsp_type)
+{
+	struct opahrs_msg_v0 req;
+	enum opahrs_result rc;
+
+	/* Make up an empty request */
+	opahrs_msg_v0_init_user_tx (&req, req_type);
+
+	/* Send the message until it is received */ 
+	rc = opahrs_msg_v0_send_req (&req);
+	if ((rc == OPAHRS_RESULT_OK) && rsp) {
+	  /* We need a specific kind of reply, go get it */
+	  return opahrs_msg_v0_recv_rsp (rsp_type, rsp);
+	}
+
+	return rc;
+}
+
+enum opahrs_result PIOS_OPAHRS_bl_GetVersions(struct opahrs_msg_v0 * rsp)
+{
+	if (!rsp) return OPAHRS_RESULT_FAILED;
+
+	return (PIOS_OPAHRS_v0_simple_req (OPAHRS_MSG_V0_REQ_VERSIONS,
+					   rsp,
+					   OPAHRS_MSG_V0_RSP_VERSIONS));
+}
+
+enum opahrs_result PIOS_OPAHRS_bl_GetSerial(struct opahrs_msg_v0 * rsp)
+{
+	if (!rsp) return OPAHRS_RESULT_FAILED;
+
+	return (PIOS_OPAHRS_v0_simple_req (OPAHRS_MSG_V0_REQ_SERIAL,
+					   rsp,
+					   OPAHRS_MSG_V0_RSP_SERIAL));
+}
+
+enum opahrs_result PIOS_OPAHRS_bl_FwupStart(struct opahrs_msg_v0 * req, struct opahrs_msg_v0 * rsp)
+{
+	if (!req || !rsp) return OPAHRS_RESULT_FAILED;
+
+	/* Make up an attituderaw request */
+	opahrs_msg_v0_init_user_tx (req, OPAHRS_MSG_V0_REQ_FWUP_START);
+
+	/* Send the message until it is received */
+	rc = opahrs_msg_v0_send_req (req);
+	if (rc != OPAHRS_RESULT_OK) {
+		/* Failed to send the request, bail out */
+		return rc;
+	}
+
+	return opahrs_msg_v0_recv_rsp (OPAHRS_MSG_V0_RSP_FWUP_STATUS, rsp);
+}
+
+enum opahrs_result PIOS_OPAHRS_bl_FwupData(struct opahrs_msg_v0 * req, struct opahrs_msg_v0 * rsp)
+{
+	if (!req || !rsp) return OPAHRS_RESULT_FAILED;
+
+	/* Make up an attituderaw request */
+	opahrs_msg_v0_init_user_tx (req, OPAHRS_MSG_V0_REQ_FWUP_DATA);
+
+	/* Send the message until it is received */
+	rc = opahrs_msg_v0_send_req (req);
+	if (rc != OPAHRS_RESULT_OK) {
+		/* Failed to send the request, bail out */
+		return rc;
+	}
+
+	return opahrs_msg_v0_recv_rsp (OPAHRS_MSG_V0_RSP_FWUP_STATUS, rsp);
+}
+
+enum opahrs_result PIOS_OPAHRS_bl_FwupVerify(struct opahrs_msg_v0 * rsp)
+{
+	if (!rsp) return OPAHRS_RESULT_FAILED;
+
+	return (PIOS_OPAHRS_v0_simple_req (OPAHRS_MSG_V0_REQ_FWUP_VERIFY,
+					   rsp,
+					   OPAHRS_MSG_V0_RSP_FWUP_STATUS));
+}
+
+
+enum opahrs_result PIOS_OPAHRS_bl_resync(void)
+{
+	struct opahrs_msg_v0 req;
+	struct opahrs_msg_v0 rsp;
+
+	enum opahrs_result rc = OPAHRS_RESULT_FAILED;
+
+	opahrs_msg_v0_init_link_tx(&req, OPAHRS_MSG_LINK_TAG_NOP);
+
+	PIOS_SPI_RC_PinSet(PIOS_OPAHRS_SPI, 0);
+#ifdef PIOS_INCLUDE_FREERTOS
+	vTaskDelay(20 / portTICK_RATE_MS);
+#else
+	PIOS_DELAY_WaitmS(20);
+#endif
+
+	for (uint32_t i = 0; i < sizeof(req); i++) {
+		/* Tx a shortened (by one byte) message to walk through all byte positions */
+		opahrs_msg_v0_init_rx(&rsp);
+		PIOS_SPI_TransferBlock(PIOS_OPAHRS_SPI, (uint8_t *)&req, (uint8_t *)&rsp, sizeof(req)-1, NULL);
+
+		/* Good magic means we're sync'd */
+		if ((rsp.head.magic == OPAHRS_MSG_MAGIC_HEAD) &&
+				(rsp.tail.magic == OPAHRS_MSG_MAGIC_TAIL)) {
+			/* We need to shift out one more byte to compensate for the short tx */
+			PIOS_SPI_TransferByte(PIOS_OPAHRS_SPI, 0x00);
+			rc = OPAHRS_RESULT_OK;
+			break;
+		}
+#ifdef PIOS_INCLUDE_FREERTOS
+		vTaskDelay(10 / portTICK_RATE_MS);
+#else
+		PIOS_DELAY_WaitmS(10);
+#endif
+	}
+
+	PIOS_SPI_RC_PinSet(PIOS_OPAHRS_SPI, 1);
+	//vTaskDelay(5 / portTICK_RATE_MS);
+
+	return rc;
+}
+
+
diff --git a/flight/PiOS/inc/pios_opahrs.h b/flight/PiOS/inc/pios_opahrs.h
index aa1239a57..6f15f9899 100644
--- a/flight/PiOS/inc/pios_opahrs.h
+++ b/flight/PiOS/inc/pios_opahrs.h
@@ -39,6 +39,22 @@ enum opahrs_result {
 };
 
 extern void PIOS_OPAHRS_Init(void);
+
+/*
+ * Protocol V0 messages used to talk to bootloaders
+ */
+
+extern enum opahrs_result PIOS_OPAHRS_bl_GetVersions(struct opahrs_msg_v0 * rsp);
+extern enum opahrs_result PIOS_OPAHRS_bl_GetSerial(struct opahrs_msg_v0 * rsp);
+extern enum opahrs_result PIOS_OPAHRS_bl_FwupStart(struct opahrs_msg_v0 * req, struct opahrs_msg_v0 * rsp);
+extern enum opahrs_result PIOS_OPAHRS_bl_FwupData(struct opahrs_msg_v0 * req, struct opahrs_msg_v0 * rsp);
+extern enum opahrs_result PIOS_OPAHRS_bl_FwupVerify(struct opahrs_msg_v0 * rsp);
+extern enum opahrs_result PIOS_OPAHRS_bl_resync(void);
+
+
+/*
+ * Protocol V1 messages used by application
+ */
 extern enum opahrs_result PIOS_OPAHRS_Sync(struct opahrs_msg_v1 *rsp);
 extern enum opahrs_result PIOS_OPAHRS_GetSerial(struct opahrs_msg_v1 *rsp);
 extern enum opahrs_result PIOS_OPAHRS_SetGetUpdate(struct opahrs_msg_v1 *rsp, struct opahrs_msg_v1 *req);