From 4c1eff0373b7a4a0072fc7515352139cd9d6d02f Mon Sep 17 00:00:00 2001
From: Fredrik Thulin <fredrik@thulin.net>
Date: Mon, 16 May 2016 15:45:02 +0200
Subject: Add code to talk with the external RTC chip.

---
 stm-rtc.c | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 stm-rtc.c

(limited to 'stm-rtc.c')

diff --git a/stm-rtc.c b/stm-rtc.c
new file mode 100644
index 0000000..85afdf4
--- /dev/null
+++ b/stm-rtc.c
@@ -0,0 +1,89 @@
+/*
+ * stm-rtc.c
+ * ----------
+ * Functions for using the externally connected RTC chip.
+ *
+ * Copyright (c) 2015-2016, NORDUnet A/S All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * - Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ *
+ * - Neither the name of the NORDUnet nor the names of its contributors may
+ *   be used to endorse or promote products derived from this software
+ *   without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "stm32f4xx_hal.h"
+#include "stm-rtc.h"
+
+I2C_HandleTypeDef hi2c_rtc;
+
+HAL_StatusTypeDef rtc_device_ready(uint16_t i2c_addr)
+{
+    return HAL_I2C_IsDeviceReady (&hi2c_rtc, i2c_addr, 10, 1000);
+}
+
+HAL_StatusTypeDef rtc_enable_oscillator()
+{
+    uint8_t buf[2];
+    HAL_StatusTypeDef res;
+
+    buf[0] = 0;		/* Offset of RTCSEC */
+    buf[1] = 1 << 7;	/* datasheet REGISTERS 5-1, bit 7 = ST (start oscillator) */
+
+    while (HAL_I2C_Master_Transmit (&hi2c_rtc, RTC_RTC_ADDR_W, buf, 2, 1000) != HAL_OK) {
+	res = HAL_I2C_GetError (&hi2c_rtc);
+	if (res != HAL_I2C_ERROR_AF) {
+	    return res;
+	}
+    }
+
+    return HAL_OK;
+}
+
+HAL_StatusTypeDef rtc_send_byte(const uint16_t i2c_addr, const uint8_t value, const uint16_t timeout)
+{
+    HAL_StatusTypeDef res;
+
+    while (HAL_I2C_Master_Transmit (&hi2c_rtc, i2c_addr, &value, 1, timeout) != HAL_OK) {
+	res = HAL_I2C_GetError (&hi2c_rtc);
+	if (res != HAL_I2C_ERROR_AF) {
+	    return res;
+	}
+    }
+
+    return HAL_OK;
+}
+
+HAL_StatusTypeDef rtc_read_bytes (const uint16_t i2c_addr, uint8_t *buf, const uint8_t len, const uint16_t timeout)
+{
+    HAL_StatusTypeDef res;
+
+    while (HAL_I2C_Master_Receive (&hi2c_rtc, i2c_addr, buf, len, 1000) != HAL_OK) {
+	res = HAL_I2C_GetError (&hi2c_rtc);
+	if (res != HAL_I2C_ERROR_AF) {
+	    return res;
+	}
+    }
+
+    return HAL_OK;
+}
-- 
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