在RT-Thread上使用龙芯1c库中的硬件I2C接口

龙芯1c库的Git是  http://git.oschina.NET/caogos/OpenLoongsonLib1c
RT-Thread的git是  https://github.com/RT-Thread/rt-thread
龙芯1c库是为龙芯1c单片机封装的常用外设接口集合，类似于STM32库。不仅可以用于裸机编程，还可以和实时系统（比如RT-Thread等）配合使用。这里就是将龙芯1c库和RT-Thread配合使用，其中龙芯1c库中硬件I2C相关接口已经移植到RT-Thread，并且合并到RT-Thread官方git中。
其实，在RT-Thread下使用龙芯1c库中的函数与在裸机编程下是一样的，都是先包含头文件，然后直接调用。
本文以温湿度传感器AM2320为例、将AM2320接在龙芯1c的I2C0（或I2C1、I2C2）上，通过RT-Thread中龙芯1c库的硬件I2C接口来读取温湿度信息，以此演示如何在RT-Thread下如何龙芯1c库中的硬件I2C接口。关于龙芯1C库中硬件I2C相关接口的详细描述请移步到【龙芯1c库】封装硬件I2C接口和使用示例

源码清单

只需要在RT-Thread下新建一个线程，然后在该线程的入口函数中调用硬件I2C接口读取温湿度信息即可，具体源码如下

bsp\ls1cdev\applications\application.c

/* * File      : application.c * This file is part of RT-Thread RTOS * COPYRIGHT (C) 2006-2012, RT-Thread Develop Team * * The license and distribution terms for this file may be * found in the file LICENSE in this distribution or at * http://www.rt-thread.org/license/LICENSE * * Change Logs: * Date                Author         Notes * 2010-06-25          Bernard        first version * 2011-08-08          lgnq           modified for Loongson LS1B * 2015-07-06          chinesebear    modified for Loongson LS1C */#include <rtthread.h>#include <components.h>#include "net/synopGMAC.h"#include <lwip/api.h>#include "rthw.h"#include "ls1c.h"#include "ls1c_public.h"#include "ls1c_i2c.h"#include "ls1c_pin.h"// 测试用的线程  #define THREAD_TEST_PRIORITY                    (25)  #define THREAD_TEST_STACK_SIZE                  (4*1024)        // 4k  #define THREAD_TEST_TIMESLICE                   (10)  // am2320返回的数据长度#define AM2320_RSP_DATA_SIZE            (8)// I2C1，引脚CAMDATA4(GPIO54)和CAMDATA5(GPIO55)的第四复用#define LS1C_I2C_SDA1_GPIO54            (54)#define LS1C_I2C_SCL1_GPIO55            (55)// I2C2，引脚CAMDATA6(GPIO56)和CAMDATA7(GPIO57)的第四复用#define LS1C_I2C_SDA2_GPIO56            (56)#define LS1C_I2C_SCL2_GPIO57            (57)// 读取的消息中每字节的含义enum{    AM2320_RSP_FUNC_ID = 0,             // 功能码    AM2320_RSP_LEN,                     // 数据长度    AM2320_RSP_HUMI_HIGH,               // 湿度高位    AM2320_RSP_HUMI_LOW,                // 湿度低位    AM2320_RSP_TEMP_HIGH,               // 温度高位    AM2320_RSP_TEMP_LOW,                // 温度低位    AM2320_RSP_CRC_LOW,                 // CRC低位    AM2320_RSP_CRC_HIGH,                // CRC高位};  struct rt_thread thread_test;  ALIGN(8) rt_uint8_t thread_test_stack[THREAD_TEST_STACK_SIZE];  /* * 计算crc * @ptr 待计算crc的数据的首地址 * @len 数据长度 */unsigned short am2320_crc16(unsigned char *ptr, unsigned char len){    unsigned short crc = 0xFFFF;    unsigned char i;    while (len--)    {        crc ^= *ptr++;        for (i=0; i<8; i++)        {            if (crc & 0x01)            {                crc >>= 1;                crc ^= 0xA001;            }            else            {                crc >>= 1;            }        }    }    return crc;}// 测试用的线程的入口  void thread_test_entry(void *parameter)  {    ls1c_i2c_info_t i2c_info;    int slave_addr = 0xb8 >> 1;     // AM2320手册中的地址0xB8是8位的，而我们这里地址是指其前7位    unsigned char send_buff[] = {0x03, 0x00, 0x04};    unsigned char recv_buff[AM2320_RSP_DATA_SIZE] = {0};    unsigned short recved_crc, calced_crc;    int temp, humi;        // I2C2，引脚CAMDATA6(GPIO56)和CAMDATA7(GPIO57)的第四复用    pin_set_remap(LS1C_I2C_SDA2_GPIO56, PIN_REMAP_FOURTH);    pin_set_remap(LS1C_I2C_SCL2_GPIO57, PIN_REMAP_FOURTH);    i2c_info.clock = 50*1000;       // 50kb/s    i2c_info.I2Cx = LS1C_I2C_2;    i2c_init(&i2c_info);    /*    // 使用I2C1，引脚CAMDATA4(GPIO54)和CAMDATA5(GPIO55)的第四复用    pin_set_remap(LS1C_I2C_SDA1_GPIO54, PIN_REMAP_FOURTH);    pin_set_remap(LS1C_I2C_SCL1_GPIO55, PIN_REMAP_FOURTH);    i2c_info.clock = 50*1000;       // 50kb/s    i2c_info.I2Cx = LS1C_I2C_1;    i2c_init(&i2c_info);*//*    // 使用I2C0，不需要复用    i2c_info.clock = 50*1000;       // 50kb/s    i2c_info.I2Cx = LS1C_I2C_0;    i2c_init(&i2c_info);*/        while (1)      {        // 唤醒传感器        i2c_send_start_and_addr(&i2c_info, slave_addr, LS1C_I2C_DIRECTION_WRITE);        i2c_receive_ack(&i2c_info);        rt_thread_delay(1);        i2c_send_stop(&i2c_info);        // 发送读指令        i2c_send_start_and_addr(&i2c_info, slave_addr, LS1C_I2C_DIRECTION_WRITE);        i2c_receive_ack(&i2c_info);        i2c_send_data(&i2c_info, send_buff, sizeof(send_buff));        i2c_send_stop(&i2c_info);        // 读取温湿度信息        rt_thread_delay(2);        i2c_send_start_and_addr(&i2c_info, slave_addr, LS1C_I2C_DIRECTION_READ);        i2c_receive_ack(&i2c_info);        i2c_receive_data(&i2c_info, recv_buff, AM2320_RSP_DATA_SIZE);        i2c_send_stop(&i2c_info);        // 校验crc        recved_crc = (recv_buff[AM2320_RSP_CRC_HIGH] << 8) + recv_buff[AM2320_RSP_CRC_LOW];        calced_crc = am2320_crc16(recv_buff, 6);        if (recved_crc != calced_crc)        {            rt_kprintf("[%s] crc error! recved_crc=0x%x, calced_crc=0x%x\n",                         __FUNCTION__, recved_crc, calced_crc);        }        // 计算温度湿度        humi = (recv_buff[AM2320_RSP_HUMI_HIGH] * 0xff + recv_buff[AM2320_RSP_HUMI_LOW]) / 10;        temp = (recv_buff[AM2320_RSP_TEMP_HIGH] * 0xff + recv_buff[AM2320_RSP_TEMP_LOW]) / 10;        rt_kprintf("[%s] temp=%d, humi=%d\n", __FUNCTION__, temp, humi);                // 间隔3s，再采集        rt_thread_delay(3 * RT_TICK_PER_SECOND);      }  }  void rt_init_thread_entry(void *parameter){/* initialization RT-Thread Components */rt_components_init();    // 网口EMAC初始化rt_hw_eth_init();}int rt_application_init(void){rt_thread_t tid;    rt_err_t result;/* create initialization thread */tid = rt_thread_create("init",rt_init_thread_entry, RT_NULL,4096, RT_THREAD_PRIORITY_MAX/3, 20);if (tid != RT_NULL)rt_thread_startup(tid);      // 初始化测试用的线程      result = rt_thread_init(&thread_test,                               "thread_test",                              thread_test_entry,                              RT_NULL,                              &thread_test_stack[0],                              sizeof(thread_test_stack),                              THREAD_TEST_PRIORITY,                              THREAD_TEST_TIMESLICE);      if (RT_EOK == result)      {          rt_thread_startup(&thread_test);      }      else      {          return -1;      }  return 0;}

运行结果（串口打印）