文章目錄
1 介紹
rx8900 軟件包是針對RT-Thread驅動框架實現的實時時鐘驅動,遵循RT-Thread RTC框架,可以從芯片內置RTC無縫切換使用外置高精度rx8900 RTC。rx8900是愛普生公司一款i2c接口
的高精度RTC芯片,集成32768Hz晶振和溫度傳感器,並能根據環境溫度調整頻率,具有供電範圍靈活、待機電流低、走時精度高等優點。
1.1 支持功能
- 實時時鐘
- 鬧鐘
- 片內溫度讀取
1.2 目錄結構
名稱 | 說明 |
---|---|
docs | 文檔目錄 |
inc | 頭文件目錄 |
src | 源代碼目錄 |
LICENSE | 許可證文件 |
SConscript | RT-Thread默認構建腳本 |
1.3 許可證
rx8900 軟件包遵循 Apache license v2.0 許可,詳見 LICENSE
文件。
1.4 依賴
- RT-Thread 3.0+
- RT-Thread I2C設備驅動框架
- RT-Thread RTC設備驅動框架
2 實現功能
實現rx8900驅動層的函數接口。
2.1 rx8900驅動描述
RT-Thread rtc驅動設備繼承其標準設備驅動,使用struct rt_device
描述rx8900設備。rx8900訪問接口是i2c,依賴於RT-Thread i2c總線框架,我們使用struct rt_device
的私有數據user_data
保存rx8900的i2c設備總線信息。後面過程則是實現struct rt_device
函數指針實體。
/**
* Device structure
*/
struct rt_device
{
struct rt_object parent; /**< inherit from rt_object */
enum rt_device_class_type type; /**< device type */
rt_uint16_t flag; /**< device flag */
rt_uint16_t open_flag; /**< device open flag */
rt_uint8_t ref_count; /**< reference count */
rt_uint8_t device_id; /**< 0 - 255 */
/* device call back */
rt_err_t (*rx_indicate)(rt_device_t dev, rt_size_t size);
rt_err_t (*tx_complete)(rt_device_t dev, void *buffer);
#ifdef RT_USING_DEVICE_OPS
const struct rt_device_ops *ops;
#else
/* common device interface */
rt_err_t (*init) (rt_device_t dev);
rt_err_t (*open) (rt_device_t dev, rt_uint16_t oflag);
rt_err_t (*close) (rt_device_t dev);
rt_size_t (*read) (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
rt_size_t (*write) (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
rt_err_t (*control)(rt_device_t dev, int cmd, void *args);
#endif
#if defined(RT_USING_POSIX)
const struct dfs_file_ops *fops;
struct rt_wqueue wait_queue;
#endif
void *user_data; /**< device private data */
};
static struct rt_device rx8900_dev; /* rx8900 device */
2.2 rx8900讀寄存器接口
static rt_err_t rx8900_write_reg(rt_device_t dev, rt_uint8_t reg, rt_uint8_t *data, rt_uint8_t data_size)
- dev,rx8900設備描述地址
- reg,寄存器地址
- data,返回數據地址(緩存)
- data_size,讀取數據長度
- 返回值,成功返回RT_EOK
2.3 rx8900寫寄存器接口
static rt_err_t rx8900_write_reg(rt_device_t dev, rt_uint8_t reg, rt_uint8_t *data, rt_uint8_t data_size)
- dev,rx8900設備描述地址
- reg,寄存器地址
- data,待寫數據地址
- data_size,待寫數據長度
- 返回值,成功返回RT_EOK
2.4 RT-Thread設備虛擬文件接口
RT-Thread設備虛擬文件接口,常用有open/read/write/control/close
,RT-Thread rtc設備框架中,關於時間和鬧鐘的設置,使用的是control
接口,實現該接口具體功能內容。
- 獲取實時時間
/* get time */
case RT_DEVICE_CTRL_RTC_GET_TIME:
time = (time_t *)args;
ret = rx8900_read_reg(dev, REG_SEC, buff, 7);
if(ret == RT_EOK)
{
time_temp.tm_year = bcd_to_hex(buff[6]) + 2000 - 1900;
time_temp.tm_mon = bcd_to_hex(buff[5]&0x1f) - 1;
time_temp.tm_mday = bcd_to_hex(buff[4]&0x3f);
time_temp.tm_hour = bcd_to_hex(buff[2]&0x3f);
time_temp.tm_min = bcd_to_hex(buff[1]&0x7f);
time_temp.tm_sec = bcd_to_hex(buff[0]&0x7f);
*time = mktime(&time_temp);
}
break;
- 設置實時時間
/* set time */
case RT_DEVICE_CTRL_RTC_SET_TIME:
{
struct tm *time_new;
time = (time_t *)args;
time_new = localtime(time);
buff[6] = hex_to_bcd(time_new->tm_year + 1900 - 2000);
buff[5] = hex_to_bcd(time_new->tm_mon + 1);
buff[4] = hex_to_bcd(time_new->tm_mday);
buff[3] = hex_to_bcd(time_new->tm_wday+1);
buff[2] = hex_to_bcd(time_new->tm_hour);
buff[1] = hex_to_bcd(time_new->tm_min);
buff[0] = hex_to_bcd(time_new->tm_sec);
ret = rx8900_write_reg(dev, REG_SEC, buff, 7);
}
break;
- 獲取鬧鐘時間
rx8900鬧鐘模式支持的最小精度是1分鐘,因此鬧鐘秒數值(tm_sec
)應設置爲0。rx8900支持天數和星期鬧鐘,RT-Thread目前鬧鐘框架暫時支持時分秒匹配,天數和星期由軟件實現。
/* get alarm time */
case RT_DEVICE_CTRL_RTC_GET_ALARM:
{
struct rt_rtc_wkalarm *alm_time;
rt_uint8_t state[3] = {0x00};
ret = rx8900_read_reg(dev, REG_ALM_MIN, buff, 2);
if(ret != RT_EOK)
{
return -RT_ERROR;
}
alm_time = (struct rt_rtc_wkalarm *)args;
alm_time->tm_hour = bcd_to_hex(buff[1]&0x7f);
alm_time->tm_min = bcd_to_hex(buff[0]&0x7f);
alm_time->tm_sec = 0; /* hardware alarm precision is 1 minute */
ret = rx8900_read_reg(dev, RGE_EXT, state, 3);
if(ret != RT_EOK)
{
return -RT_ERROR;
}
if (state[0] & VALUE_EXT_WADA)
{/* day alarm */
/* todo, RTT not supported temporarily */
}
else
{/* week day alarm */
/* todo, RTT not supported temporarily */
}
}
- 設置鬧鐘時間
針對RT-Thread鬧鐘框架,rx8900鬧鐘禁止天數(tm_day
)和星期(tm_wday
)匹配功能,只設置小時(tm_hour
)和分鐘(tm_minute
),同時將秒數(tm_sec
)設爲0。
/* set alarm time */
case RT_DEVICE_CTRL_RTC_SET_ALARM:
{
struct rt_rtc_wkalarm *alm_time;
rt_uint8_t ctrl[2] = {0x00};
alm_time = (struct rt_rtc_wkalarm *)args;
buff[2] = ALM_DISABLE(0x00); /* week and day alarm disable */
buff[1] = hex_to_bcd(ALM_ENABLE(alm_time->tm_hour));/* enable, alarm when hours and minutes match */
buff[0] = hex_to_bcd(ALM_ENABLE(alm_time->tm_min));
ret = rx8900_read_reg(dev, REG_FLAG, ctrl, 2);
if (ret != RT_EOK)
{
return -RT_ERROR;
}
if (ctrl[0]&VALUE_EXT_WADA)
{/* day alarm */
/* todo, RTT not supported temporarily */
}
else
{/* week day alarm */
/* todo, RTT not supported temporarily */
}
/* write to hardware */
ret = rx8900_write_reg(dev, REG_ALM_MIN, buff, 3);
if (ret != RT_EOK)
{
return -RT_ERROR;
}
/* clear alarm flag */
ctrl[1] &= ~VALUE_FLAG_AF;
ret = rx8900_write_reg(dev, REG_FLAG, &ctrl[1], 1);
}
break;
2.5 片內溫度獲取接口
rx8900內部集成一個溫度傳感器和溫度校準係數,讀取溫度寄存器值通過一定的換算公式計算出實際溫度。rx8900芯片手冊提供攝氏度(℃)與寄存器值轉換公式如下。
獲取溫度接口
/*
* @brief Read temperature from rx8900
* @return Celsius temperature,-55~+125C,0.1C
*/
float rx8900_get_temperature(void)
{
rt_uint8_t value = 0;
float temp = 0.0f;
rx8900_read_reg(&rx8900_dev, REG_TEMP, (rt_uint8_t*)&value, 1);
temp = (value*2-187.19)/3.218;
return temp;
}
我們把溫度讀取接口註冊到RT-Thread的調試終端(msh/finsh),方便測試。
#ifdef RT_USING_FINSH
#include <finsh.h>
void list_rx89_temp(void)
{
float temp = 0.0f;
temp = rx8900_get_temperature();
rt_kprintf("rx8900 temperature: [%d.%dC] \n", (int)temp, (int)(temp * 10) % 10);
}
FINSH_FUNCTION_EXPORT(list_rx89_temp, list rx8900 temperature.)
#endif /* RT_USING_FINSH */
#if defined(RT_USING_FINSH) && defined(FINSH_USING_MSH)
MSH_CMD_EXPORT(list_rx89_temp, list rx8900 temperature.);
#endif /* RT_USING_FINSH & FINSH_USING_MSH */
2.6 rtc設備註冊
rx8900設備註冊
- rx8900使用的是系統
“i2c1”
,i2c1驅動請自行初始化註冊;否則rx8900設備註冊失敗 - rx8900設備中
user_data
保存i2c1總線信息,用於後續訪問rx8900 - rx8900設備名稱保持與rtc設備框架的rtc名稱一致,統一爲
“rtc”
int rt_hw_rx8900_init(void)
{
struct rt_i2c_bus_device *i2c_bus =RT_NULL;
rt_uint8_t flags = 0;
rt_bool_t need_clear = RT_FALSE;
rt_bool_t need_reset = RT_FALSE;
i2c_bus = rt_i2c_bus_device_find(RX8900_I2C_BUS);
if (i2c_bus == RT_NULL)
{
LOG_E("i2c bus device %s not found!\r\n", RX8900_I2C_BUS);
return -RT_ERROR;
}
/* register rtc device */
rx8900_dev.type = RT_Device_Class_RTC;
rx8900_dev.init = RT_NULL;
rx8900_dev.open = rt_rx8900_open;
rx8900_dev.close = RT_NULL;
rx8900_dev.read = rt_rx8900_read;
rx8900_dev.write = RT_NULL;
rx8900_dev.control = rt_rx8900_control;
rx8900_dev.user_data= (void*)i2c_bus; /* save i2cbus */
rt_device_register(&rx8900_dev, RX8900_DEVICE_NAME, RT_DEVICE_FLAG_RDWR);
......
}
rx8900私有信息初始化
rx8900私有信息初始化主要包括:
- 獲取rx8900狀態寄存器值
- 根據狀態寄存器值每一bit的含義執行復位、初始化操作或者清除狀態寄存器操作
if (flags & VALUE_FLAG_VDET)
{
LOG_D("Temperature compensation stop detected.\n");
need_clear = RT_TRUE;
}
/* alarm */
if (flags & VALUE_FLAG_AF)
{
LOG_D("Alarm was detected.\n");
need_clear = RT_TRUE;
}
/* timer */
if (flags & VALUE_FLAG_TF)
{
LOG_D("Timer was detected.\n");
need_clear = RT_TRUE;
}
......
3 獲取 rx8900 軟件包
使用 rx8900 package, 需要在 RT-Thread 的包管理器中選擇它,具體路徑如下:
RT-Thread online packages --->
peripheral libraries and drivers --->
[*] extren rtc drivers --->
[*] rx8900:Extern RTC drivers fo rx8900
Version (latest) --->
然後讓 RT-Thread 的包管理器自動更新,或者執行 pkgs --update
命令更新包到 BSP 中。
4 使用 rx8900 軟件包
4.1 初始化
首先需初始化rx8900 驅動,可以手動在初始化線程合適的地方調用rt_hw_rx8900 _init()
初始化,也可以直接使用INIT_DEVICE_EXPORT
通過RT-Thread的自動初始化機制來初始化註冊。初始化成功後,會註冊名稱爲“rtc”
的驅動設備。
INIT_DEVICE_EXPORT(rt_hw_rx8900_init); /* 通過RTT的自動初始化機制初始化rx8900 */
注:
如果開啓了芯片內部RTC,需先禁止內部RTC
4.2 使用方式
查看設備是否註冊成功。
對於時間和鬧鐘的訪問,使用RT-Thread標準RTC和鬧鐘接口訪問。片內溫度讀取,則由軟件包提供一個函數接口。
- 獲取當前時間
time_t time(time_t *t)
time_t now;
now = time(RT_NULL);
- 設置時間
#define RT_DEVICE_CTRL_RTC_SET_TIME 0x11 /**< set time */
rt_err_t rt_device_control(rt_device_t dev, int cmd, void *arg);
- 獲取鬧鐘時間
#define RT_DEVICE_CTRL_RTC_GET_ALARM 0x12 /**< get alarm */
rt_err_t rt_device_control(rt_device_t dev, int cmd, void *arg);
- 設置鬧鐘時間
#define RT_DEVICE_CTRL_RTC_SET_ALARM 0x13 /**< set alarm */
rt_err_t rt_device_control(rt_device_t dev, int cmd, void *arg);
注:
詳細用法可以參考“/components/drivers/rtc.c”和“/components/drivers/alarm.c”源碼。
- 提供一個獲取片內溫度接口
float rx8900_get_temperature(void);
4.3 msh/finsh測試
- msh獲取時間
msh >date
Sat Jan 1 00:00:04 2000
- msh設置時間
msh date 2020 04 10 17 41 10
msh >date
Fri Apr 10 17:41:15 2020
- finsh獲取時間
finsh >list_date()
Fri Apr 10 17:41:49 2020
- finsh設置時間
finsh >set_date(2020,5,1)
0, 0x00000000
finsh >set_time(12,0,0)
0, 0x00000000
finsh >list_date()
Fri May 1 12:00:04 2020
- msh打印溫度
msh >list_rx89_temp
rx8900 temperature: [27.5C]
- finsh打印溫度
finsh >list_rx89_temp()
rx8900 temperature: [27.5C]
5 注意事項
使用RT-Thread的RTC框架,RTC設備註冊名稱爲“rtc”
,注意需先屏蔽芯片內置RTC驅動。