boards/arm/stm32/stm32f4discovery/src: Add support for external DS1307 module.

boards/arm/stm32/stm32f4discovery/README.txt

@@ -38,6 +38,7 @@ Contents
   - Quadrature Encoder
   - FPU
   - STM32F4DIS-BB
+  - RTC DS1307
   - SSD1289
   - UG-2864AMBAG01 / UG-2864HSWEG01
   - HCI UART
@@ -417,6 +418,52 @@ On-board PIO usage:
   PC10       DAT2
   ---------- ------------- ------------------------------
 
+RTC DS1307
+==========
+
+It is possible to use a low cost extern DS1307 RTC to keep date and time
+always updated. These DS1307 RTC modules come with a 3V button battery, then
+even when the board is turned OFF the Date/Time registers keep running.
+
+You can connect the module this way (STM32F4Discovery to DS1307 board): GND
+to GND; 5V to VCC; PB9 to SDA; PB6 to SCL. In the NuttX menuconfig you need
+to enable these options:
+
+System Type  --->
+    STM32 Peripheral Support  --->
+        [*] I2C1
+
+Device Drivers  --->
+    Timer Driver Support  --->
+        [*] RTC Driver Support  --->
+            -*-   Date/Time RTC Support
+            [*]   External RTC Support
+            [*]     DS130x/DS323x RTC Driver
+                      Maxim Integrated RTC (DS1307)  --->
+            (100000)  DS1307/DS323x I2C frequency
+
+Application Configuration  --->
+    NSH Library  --->
+        Disable Individual commands  --->
+            [ ] Disable date ( <-- Deselect )
+
+It is also a good idea to enable the DEBUG to RTC initially, you will see:
+
+ABCDF
+stm32_ds1307_init: Initialize I2C1
+stm32_ds1307_init: Bind the DS1307 RTC driver to I2C1
+rtc_dumptime: Returning:
+rtc_dumptime:    tm_sec: 00000039
+rtc_dumptime:    tm_min: 00000001
+rtc_dumptime:   tm_hour: 00000009
+rtc_dumptime:   tm_mday: 00000016
+rtc_dumptime:    tm_mon: 00000008
+rtc_dumptime:   tm_year: 00000077
+
+NuttShell (NSH)
+nsh> date
+Sep 22 09:01:58 2019
+
 SSD1289
 =======
 

boards/arm/stm32/stm32f4discovery/src/Makefile

@@ -125,6 +125,10 @@ ifeq ($(CONFIG_RGBLED),y)
 CSRCS += stm32_rgbled.c
 endif
 
+ifeq ($(CONFIG_RTC_DS1307),y)
+CSRCS += stm32_ds1307.c
+endif
+
 ifeq ($(CONFIG_PWM),y)
 CSRCS += stm32_pwm.c
 endif

boards/arm/stm32/stm32f4discovery/src/stm32_bringup.c

@@ -329,6 +329,15 @@ int stm32_bringup(void)
     }
 #endif
 
+#ifdef CONFIG_RTC_DS1307
+  ret = stm32_ds1307_init();
+  if (ret < 0)
+    {
+      syslog(LOG_ERR, "Failed to initialize DS1307 RTC driver: %d\n", ret);
+      return ret;
+    }
+#endif
+
 #ifdef HAVE_RTC_DRIVER
   /* Instantiate the STM32 lower-half RTC driver */
 

boards/arm/stm32/stm32f4discovery/src/stm32_ds1307.c

@@ -0,0 +1,128 @@
+/****************************************************************************
+ * boards/arm/stm32/stm32f4discovery/src/stm32_ds1307.c
+ *
+ *   Copyright (C) 2019 Alan Carvalho de Assis. All rights reserved.
+ *   Author: Alan Carvalho de Assis <acassis@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name NuttX 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 OWNER 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <errno.h>
+#include <debug.h>
+
+#include <nuttx/i2c/i2c_master.h>
+#include <nuttx/timers/rtc.h>
+#include <nuttx/timers/ds3231.h>
+
+#include "stm32.h"
+#include "stm32_i2c.h"
+#include "stm32f4discovery.h"
+
+#if defined(CONFIG_I2C) && defined(CONFIG_RTC_DS1307)
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define DS1307_I2C_ADDR    0x6f /* DS1307 I2C Address */
+#define DS1307_I2C_BUS     1    /* DS1307 is on I2C1 */
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: stm32_ds1307_init
+ *
+ * Description:
+ *   Initialize and configure the DS1307 RTC
+ *
+ ****************************************************************************/
+
+int stm32_ds1307_init(void)
+{
+  FAR struct i2c_master_s *i2c;
+  static bool initialized = false;
+  int ret;
+
+  /* Have we already initialized? */
+
+  if (!initialized)
+    {
+      /* No.. Get the I2C bus driver */
+
+      rtcinfo("Initialize I2C%d\n", DS1307_I2C_BUS);
+      i2c = stm32_i2cbus_initialize(DS1307_I2C_BUS);
+      if (!i2c)
+        {
+          rtcerr("ERROR: Failed to initialize I2C%d\n", DS1307_I2C_BUS);
+          return -ENODEV;
+        }
+
+      /* Now bind the I2C interface to the DS1307 RTC driver */
+
+      rtcinfo("Bind the DS1307 RTC driver to I2C%d\n", DS1307_I2C_BUS);
+      ret = dsxxxx_rtc_initialize(i2c);
+      if (ret < 0)
+        {
+          rtcerr("ERROR: Failed to bind I2C%d to the DS1307 RTC driver\n",
+                 DS1307_I2C_BUS);
+          return -ENODEV;
+        }
+
+#ifdef CONFIG_I2C_DRIVER
+      /* Register the I2C to get the "nsh> i2c bus" command working */
+
+      ret = i2c_register(i2c, DS1307_I2C_BUS);
+      if (ret < 0)
+        {
+          rtcerr("ERROR: Failed to register I2C%d driver: %d\n", bus, ret);
+          return -ENODEV;
+        }
+#endif
+
+      /* Synchronize the system time to the RTC time */
+
+      clock_synchronize();
+
+      /* Now we are initialized */
+
+      initialized = true;
+    }
+
+  return OK;
+}
+
+#endif /* CONFIG_I2C && CONFIG_RTC_DS1307 */

boards/arm/stm32/stm32f4discovery/src/stm32f4discovery.h

@@ -216,6 +216,7 @@
 #endif
 
 /* STM32F4 Discovery GPIOs **************************************************/
+
 /* LEDs */
 
 #define GPIO_LED1       (GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_50MHz|\
@@ -497,6 +498,18 @@ int nunchuck_initialize(FAR char *devname);
 int stm32_max7219init(FAR const char *devpath);
 #endif
 
+/****************************************************************************
+ * Name: stm32_ds1307_init
+ *
+ * Description:
+ *   Initialize and register the DS1307 RTC
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_RTC_DS1307
+int stm32_ds1307_init(void);
+#endif
+
 /****************************************************************************
  * Name: stm32_st7032init
  *