Add support for setting and reading alarm

CHANGELOG.md

@@ -5,6 +5,7 @@ All notable changes to this project will be documented in this file, in reverse
 ## [0.5.0](https://github.com/tuupola/bm8563/compare/0.4.0...master) - unreleased
 
 ### Added
+- Support for reading and writing alarms ([#4](https://github.com/tuupola/bm8563/pull/4)).
 - Support for low voltage warnings ([#3](https://github.com/tuupola/bm8563/pull/3)).
 
 ## 0.4.0 - 2020-20-05

README.md

@@ -69,6 +69,52 @@ bm8563_init(&bm);
 bm8563_write(&bm, &rtc);
 ```
 
+## Set RTC alarm
+
+```c
+#include <time.h>
+
+#include "bm8563.h"
+#include "user_i2c.h"
+
+struct tm rtc_alarm;
+bm8563_t bm;
+
+/* Add pointers to user provided functions. */
+bm.read = &user_i2c_read;
+bm.write = &user_i2c_write;
+
+bm8563_init(&bm);
+
+/* Add alarm every day at 21:30. */
+rtc_alarm.tm_min = 30;
+rtc_alarm.tm_hour = 21;
+rtc_alarm.tm_mday = BM8563_ALARM_NONE;
+rtc_alarm.tm_wday = BM8563_ALARM_NONE;
+
+bm8563_ioctl(&bm, BM8563_ALARM_SET, &rtc_alarm);
+```
+
+## Read RTC alarm
+
+```c
+#include <time.h>
+
+#include "bm8563.h"
+#include "user_i2c.h"
+
+struct tm rtc_alarm;
+bm8563_t bm;
+
+/* Add pointers to user provided functions. */
+bm.read = &user_i2c_read;
+bm.write = &user_i2c_write;
+
+bm8563_init(&bm);
+
+bm8563_ioctl(&bm, BM8563_ALARM_READ, &rtc_alarm);
+```
+
 ## License
 
 The MIT License (MIT). Please see [License File](LICENSE.txt) for more information.

bm8563.c

@@ -158,6 +158,109 @@ bm8563_err_t bm8563_write(const bm8563_t *bm, const struct tm *time)
     return bm->write(bm->handle, BM8563_ADDRESS, BM8563_SECONDS, buffer, BM8563_TIME_SIZE);
 }
 
+
+bm8563_err_t bm8563_ioctl(const bm8563_t *bm, int16_t command, void *argument)
+{
+    uint8_t reg = command >> 8;
+    uint8_t buffer[BM8563_ALARM_SIZE] = {0};
+    uint8_t status;
+    struct tm *time;
+
+    switch (command) {
+    case BM8563_ALARM_SET:
+        time = (struct tm *)argument;
+
+        /* 0..59 */
+        if (BM8563_ALARM_NONE == time->tm_min) {
+            buffer[0] = 0x00;
+        } else {
+            buffer[0] = decimal2bcd(time->tm_min);
+            buffer[0] |= BM8563_ALARM_ENABLE;
+        }
+
+        /* 0..23 */
+        if (BM8563_ALARM_NONE == time->tm_hour) {
+            buffer[1] = 0x00;
+        } else {
+            buffer[1] = decimal2bcd(time->tm_hour);
+            buffer[1] &= 0b00111111;
+            buffer[1] |= BM8563_ALARM_ENABLE;
+        }
+
+        /* 1..31 */
+        if (BM8563_ALARM_NONE == time->tm_mday) {
+            buffer[2] = 0x00;
+        } else {
+            buffer[2] = decimal2bcd(time->tm_mday);
+            buffer[2] &= 0b00111111;
+            buffer[2] |= BM8563_ALARM_ENABLE;
+        }
+
+        /* 0..6 */
+        if (BM8563_ALARM_NONE == time->tm_mday) {
+            buffer[3] = 0x00;
+        } else {
+            buffer[3] = decimal2bcd(time->tm_wday);
+            buffer[3] &= 0b00000111;
+            buffer[3] |= BM8563_ALARM_ENABLE;
+        }
+
+        return bm->write(
+            bm->handle, BM8563_ADDRESS, reg, buffer, BM8563_ALARM_SIZE
+        );
+
+        break;
+
+    case BM8563_ALARM_READ:
+        time = (struct tm *)argument;
+
+        /* 0..59 */
+        status = bm->read(
+            bm->handle, BM8563_ADDRESS, reg, buffer, BM8563_ALARM_SIZE
+        );
+
+        if (BM8563_OK != status) {
+            return status;
+        }
+
+        if (BM8563_ALARM_ENABLE & buffer[0]) {
+            buffer[0] &= 0b01111111;
+            time->tm_min = bcd2decimal(buffer[0]);
+        } else {
+            time->tm_min = BM8563_ALARM_NONE;
+        }
+
+        /* 0..23 */
+        if (BM8563_ALARM_ENABLE & buffer[1]) {
+            buffer[1] &= 0b00111111;
+            time->tm_hour = bcd2decimal(buffer[1]);
+        } else {
+            time->tm_hour = BM8563_ALARM_NONE;
+        }
+
+        /* 1..31 */
+        if (BM8563_ALARM_ENABLE & buffer[2]) {
+            buffer[2] &= 0b00111111;
+            time->tm_mday = bcd2decimal(buffer[2]);
+        } else {
+            time->tm_mday = BM8563_ALARM_NONE;
+        }
+
+        /* 0..6 */
+        if (BM8563_ALARM_ENABLE & buffer[3]) {
+            buffer[3] &= 0b00000111;
+            time->tm_wday = bcd2decimal(buffer[3]);
+        } else {
+            time->tm_wday = BM8563_ALARM_NONE;
+        }
+
+        return BM8563_OK;
+        break;
+    }
+
+    return BM8563_ERROR_NOTTY;
+}
+
 bm8563_err_t bm8563_close(const bm8563_t *bm)
 {
     return BM8563_OK;

bm8563.h

@@ -43,7 +43,15 @@ extern "C" {
 
 #define	BM8563_ADDRESS	        (0x51)
 #define	BM8563_CONTROL_STATUS_1 (0x00)
+#define	BM8563_TESTC            (0b00001000)
+#define	BM8563_STOP             (0b00100000)
+#define	BM8563_TEST1            (0b10000000)
 #define	BM8563_CONTROL_STATUS_2 (0x01)
+#define	BM8563_TIE              (0b00000001)
+#define	BM8563_AIE              (0b00000010)
+#define	BM8563_TF               (0b00000100)
+#define	BM8563_AF               (0b00001000)
+#define	BM8563_TI_TP            (0b00010000)
 #define	BM8563_SECONDS          (0x02)
 #define	BM8563_MINUTES          (0x03)
 #define	BM8563_HOURS            (0x04)
@@ -54,6 +62,20 @@ extern "C" {
 #define	BM8563_TIME_SIZE        (0x07)
 #define	BM8563_CENTURY_BIT      (0b10000000)
 
+#define BM8563_MINUTE_ALARM     (0x09)
+#define BM8563_HOUR_ALARM       (0x0a)
+#define BM8563_DAY_ALARM        (0x0b)
+#define BM8563_WEEKDAY_ALARM    (0x0c)
+#define BM8563_ALARM_ENABLE     (0b10000000)
+#define BM8563_ALARM_NONE       (0xff)
+#define BM8563_ALARM_SIZE       (0x04)
+
+/* IOCTL commands */
+#define BM8563_ALARM_SET        (0x0900)
+#define BM8563_ALARM_READ       (0x0901)
+
+/* Status codes. */
+#define BM8563_ERROR_NOTTY      (-1)
 #define BM8563_OK               (0x00)
 #define BM8563_ERR_LOW_VOLTAGE  (0x80)
 
@@ -69,6 +91,7 @@ typedef int32_t bm8563_err_t;
 bm8563_err_t bm8563_init(const bm8563_t *bm);
 bm8563_err_t bm8563_read(const bm8563_t *bm, struct tm *time);
 bm8563_err_t bm8563_write(const bm8563_t *bm, const struct tm *time);
+bm8563_err_t bm8563_ioctl(const bm8563_t *bm, int16_t command, void *buffer);
 bm8563_err_t bm8563_close(const bm8563_t *bm);
 
 #ifdef __cplusplus