FRDM-MCXN947开发板之i2c应用
介绍MCXN947
NXP FRDM-MCXN947开发板是一款基于MCXN947 MCU的低成本评估板，MCU集成了双核Arm Cortex-M33微控制器和一个神经处理单元(NPU)。开发板由一个MCXN947控制器和一个64 Mbit外部串行闪存组成。该板还具有P3T1755DP I3C温度传感器，TJA1057GTK/3Z CAN PHY，以太网PHY, SDHC电路(卡槽为DNP)， RGB LED，触摸板，高速USB，按钮，和MCU-Link调试接口。该板兼容Arduino屏蔽模块，Pmod板，mikroBUS。该板还支持摄像头模块和NXP低成本LCD模块PAR-LCD-S035
开箱视频
我通过参过RT-Thread社区的活动，拿到了京东的包裹，板子的开箱视频：FRDM-MCXN947开发板开箱_哔哩哔哩_bilibili
开发环境
基本的开发资料有以下几个，软件包或者资料都可以在NXP官网、Keil的官网找到，插一句话，最近Keil免费了
[*]MDK531
[*]NXP.MCXN947_DFP.17.0.0
[*]rt_vsnprintf_full-latest.zip开发包
[*]官方的文档：UM12018.pdf
[*]RT-Thread GitHub仓库最新代码
开发环境搭建请参考视频：FRDM-MCXN947开发板开发环境上手_哔哩哔哩_bilibili
实验目的
最近南方地区都在下暴雨，气候闷热潮湿，人们出门都在时刻关注天气的变化情况；刚好这个时候RT-Thread社区给我送来一款包装精致的NXP开发板，让我手头上的BME280温湿度气压传感器有了用武之地；BME280采用i2c接口和主机通信，能实时监控室内、室外的温度、湿度、大气压情况，基于它我们能做很多工业、物联网、医疗、汽车方面的应用
实验准备
我们需要准备以下材料
[*]NXP FRDM-MCXN947开发板
[*]温湿度气压模块BME280 （i2c接口）
[*]SSD1306 OLED模块（i2c接口）
[*]公母头杜邦线若干
模块电路
板载资源
本次实验是通过软件i2c + 硬件i2c方式来进行通信，软件i2c采用引脚P0_4 (SCL)和P0_5 (SDA) ，硬件i2c采用引脚P0_25 (SCL)和P0_24 (SDA)，前者位于J9内侧的第8和第9引脚，后者位于J2外侧的第7和第5引脚，引脚图参考如下，注意不要接错
实物连接
软件i2c口接OLED SSD1306模块，硬件i2c口接BME280模块，电源VCC和GND在J8和J6上面都有，千万别接错了！
程序设计
模块配置
克隆rt-thread官方仓库的代码，MCXN947板子的最小例程在bsp\nxp\mcx\mcxn\frdm-mcxn947目录下
git clone https://github.com/RT-Thread/rt-thread.git用RT-Thread Studio导入frdm-mcxn947工程，然后打开env工具
https://img2024.cnblogs.com/blog/1031983/202406/1031983-20240607222646718-384142722.png
在env终端输入命令menuconfig，配置rt-thread工程
在RT-Thread Components下找到Device Drivers并Select进去，软件i2c引脚配置如下
在Hardware Drivers Config下找到On-chip Peripheral Drivers并Select进去，硬件i2c引脚配置如下
找到RT-Thread online packages -> peripheral libraries and drivers -> ssd1306并Select进去，配置SSD1306模块，记得改掉I2c bus name和开启ssd1306的sample选项，这里名称为i2c2，和上面配置的软件i2c名称一致
配置完后通过Exit退出，先更新软件包，再导出为mdk5工程，然后用Keil5打开
pkgs --update
scons --target=mdk5编译工程
需要注释一些代码确保编译通过
ssd1306_tests.h
ssd1306.h
编码集成
SSD1306
调用初始化接口并设置背景为黑色
ssd1306_Init();
ssd1306_Fill(Black);绘图接口示范，先往buffer里边填字符串数据，然后设置坐标，再绘制字符
rt_memset(buffer, SIZE, 0);
rt_snprintf(buffer, SIZE, "Temp : %d'C\r\n",(int)temp_act);
ssd1306_SetCursor(2, 26);
ssd1306_WriteString(buffer, Font_6x8, White);BME280
readCalibrationData、calibration_T、calibration_P、calibration_H用于读取和校准BME280的数据
static unsigned long int hum_raw,temp_raw,pres_raw;
static rt_uint8_t data;
static signed long int t_fine;
static uint16_t dig_T1;
static int16_t dig_T2;
static int16_t dig_T3;
static uint16_t dig_P1;
static int16_t dig_P2;
static int16_t dig_P3;
static int16_t dig_P4;
static int16_t dig_P5;
static int16_t dig_P6;
static int16_t dig_P7;
static int16_t dig_P8;
static int16_t dig_P9;
static int8_tdig_H1;
static int16_t dig_H2;
static int8_tdig_H3;
static int16_t dig_H4;
static int16_t dig_H5;
static int8_tdig_H6;
static signed long int temp_cal;
static unsigned long int press_cal,hum_cal;
static double temp_act;
static double press_act;
static double hum_act;
static void readCalibrationData()
{
uint8_t data;
read_bme280_reg(0x88, data, 24);
read_bme280_reg(0xa1, data + 24, 1);
read_bme280_reg(0xe1, data + 25, 7);
dig_T1 = (data << 8) | data;
dig_T2 = (data << 8) | data;
dig_T3 = (data << 8) | data;
dig_P1 = (data << 8) | data;
dig_P2 = (data << 8) | data;
dig_P3 = (data<< 8) | data;
dig_P4 = (data<< 8) | data;
dig_P5 = (data<< 8) | data;
dig_P6 = (data<< 8) | data;
dig_P7 = (data<< 8) | data;
dig_P8 = (data<< 8) | data;
dig_P9 = (data<< 8) | data;
dig_H1 = data;
dig_H2 = (data<< 8) | data;
dig_H3 = data;
dig_H4 = (data<< 4) | (0x0F & data);
dig_H5 = (data << 4) | ((data >> 4) & 0x0F);
dig_H6 = data;
}
static signed long int calibration_T(signed long int adc_T)
{
signed long int var1, var2, T;
var1 = ((((adc_T >> 3) - ((signed long int)dig_T1<<1))) * ((signed long int)dig_T2)) >> 11;
var2 = (((((adc_T >> 4) - ((signed long int)dig_T1)) * ((adc_T>>4) - ((signed long int)dig_T1))) >> 12) * ((signed long int)dig_T3)) >> 14;
t_fine = var1 + var2;
T = (t_fine * 5 + 128) >> 8;
return T;
}
static unsigned long int calibration_P(signed long int adc_P)
{
signed long int var1, var2;
unsigned long int P;
var1 = (((signed long int)t_fine)>>1) - (signed long int)64000;
var2 = (((var1>>2) * (var1>>2)) >> 11) * ((signed long int)dig_P6);
var2 = var2 + ((var1*((signed long int)dig_P5))<<1);
var2 = (var2>>2)+(((signed long int)dig_P4)<<16);
var1 = (((dig_P3 * (((var1>>2)*(var1>>2)) >> 13)) >>3) + ((((signed long int)dig_P2) * var1)>>1))>>18;
var1 = ((((32768+var1))*((signed long int)dig_P1))>>15);
if (var1 == 0)
{
return 0;
}
P = (((unsigned long int)(((signed long int)1048576)-adc_P)-(var2>>12)))*3125;
if(P<0x80000000)
{
P = (P << 1) / ((unsigned long int) var1);
}
else
{
P = (P / (unsigned long int)var1) * 2;
}
var1 = (((signed long int)dig_P9) * ((signed long int)(((P>>3) * (P>>3))>>13)))>>12;
var2 = (((signed long int)(P>>2)) * ((signed long int)dig_P8))>>13;
P = (unsigned long int)((signed long int)P + ((var1 + var2 + dig_P7) >> 4));
return P;
}
static unsigned long int calibration_H(signed long int adc_H)
{
signed long int v_x1;
v_x1 = (t_fine - ((signed long int)76800));
v_x1 = (((((adc_H << 14) -(((signed long int)dig_H4) << 20) - (((signed long int)dig_H5) * v_x1)) +
((signed long int)16384)) >> 15) * (((((((v_x1 * ((signed long int)dig_H6)) >> 10) *
(((v_x1 * ((signed long int)dig_H3)) >> 11) + ((signed long int) 32768))) >> 10) + (( signed long int)2097152)) *
((signed long int) dig_H2) + 8192) >> 14));
v_x1 = (v_x1 - (((((v_x1 >> 15) * (v_x1 >> 15)) >> 7) * ((signed long int)dig_H1)) >> 4));
v_x1 = (v_x1 < 0 ? 0 : v_x1);
v_x1 = (v_x1 > 419430400 ? 419430400 : v_x1);
return (unsigned long int)(v_x1 >> 12);
}i2c读写接口封装
static int read_bme280_reg(rt_uint8_t reg_addr, rt_uint8_t *data, rt_uint8_t len)
{
struct rt_i2c_msg msgs;
msgs.addr = BME280_ADDR;
msgs.flags = RT_I2C_WR;
msgs.buf = ®_addr;
msgs.len = 1;
msgs.addr = BME280_ADDR;
msgs.flags = RT_I2C_RD;
msgs.buf = data;
msgs.len = len;
if (rt_i2c_transfer(i2c_bus, msgs, 2) == 2)
{
return RT_EOK;
}
else
return -RT_ERROR;
}
static int8_t write_bme280_reg(uint8_t reg, uint8_t *data, uint16_t len)
{
rt_uint8_t tmp = reg;
struct rt_i2c_msg msgs;
msgs.addr= BME280_ADDR; /* Slave address */
msgs.flags = RT_I2C_WR; /* Write flag */
msgs.buf = &tmp; /* Slave register address */
msgs.len = 1; /* Number of bytes sent */
msgs.addr= BME280_ADDR; /* Slave address */
msgs.flags = RT_I2C_WR | RT_I2C_NO_START; /* Read flag */
msgs.buf = data; /* Read data pointer */
msgs.len = len; /* Number of bytes read */
if (rt_i2c_transfer(i2c_bus, msgs, 2) != 2)
{
return -RT_ERROR;
}
return RT_EOK;
}init_bme280用于初始化i2c设备
static int init_bme280(void){ i2c_bus = (struct rt_i2c_bus_device *) rt_device_find(BME280_I2C_BUS_NAME); if (i2c_bus == RT_NULL) { rt_kprintf("can't find %s device!\n", BME280_I2C_BUS_NAME); return RT_ERROR; } rt_uint8_t data; int size = read_bme280_reg(0xD0, &data, 1); rt_kprintf("bme280 device id : %x\n", data); uint8_t osrs_t = 1; //Temperature oversampling x 1 uint8_t osrs_p = 1; //Pressure oversampling x 1 uint8_t osrs_h = 1; //Humidity oversampling x 1 uint8_t mode = 3; //Normal mode uint8_t t_sb = 5; //Tstandby 1000ms uint8_t filter = 0; //Filter off uint8_t spi3w_en = 0; //3-wire SPI Disable uint8_t ctrl_meas_reg = (osrs_t4) - ((signed long int)dig_T1)) * ((adc_T>>4) - ((signed long int)dig_T1))) >> 12) * ((signed long int)dig_T3)) >> 14; t_fine = var1 + var2; T = (t_fine * 5 + 128) >> 8; return T;}static unsigned long int calibration_P(signed long int adc_P){ signed long int var1, var2; unsigned long int P; var1 = (((signed long int)t_fine)>>1) - (signed long int)64000; var2 = (((var1>>2) * (var1>>2)) >> 11) * ((signed long int)dig_P6); var2 = var2 + ((var1*((signed long int)dig_P5))2)+(((signed long int)dig_P4)2)*(var1>>2)) >> 13)) >>3) + ((((signed long int)dig_P2) * var1)>>1))>>18; var1 = ((((32768+var1))*((signed long int)dig_P1))>>15); if (var1 == 0) { return 0; } P = (((unsigned long int)(((signed long int)1048576)-adc_P)-(var2>>12)))*3125; if(P3) * (P>>3))>>13)))>>12; var2 = (((signed long int)(P>>2)) * ((signed long int)dig_P8))>>13; P = (unsigned long int)((signed long int)P + ((var1 + var2 + dig_P7) >> 4)); return P;}static unsigned long int calibration_H(signed long int adc_H){ signed long int v_x1; v_x1 = (t_fine - ((signed long int)76800)); v_x1 = (((((adc_H15) * (((((((v_x1 * ((signed long int)dig_H6)) >> 10) * (((v_x1 * ((signed long int)dig_H3)) >> 11) + ((signed long int) 32768))) >> 10) + (( signed long int)2097152)) * ((signed long int) dig_H2) + 8192) >> 14)); v_x1 = (v_x1 - (((((v_x1 >> 15) * (v_x1 >> 15)) >> 7) * ((signed long int)dig_H1)) >> 4)); v_x1 = (v_x1 < 0 ? 0 : v_x1); v_x1 = (v_x1 > 419430400 ? 419430400 : v_x1); return (unsigned long int)(v_x1 >> 12);}static int read_bme280_reg(rt_uint8_t reg_addr, rt_uint8_t *data, rt_uint8_t len){ struct rt_i2c_msg msgs; msgs.addr = BME280_ADDR; msgs.flags = RT_I2C_WR; msgs.buf = ®_addr; msgs.len = 1; msgs.addr = BME280_ADDR; msgs.flags = RT_I2C_RD; msgs.buf = data; msgs.len = len; if (rt_i2c_transfer(i2c_bus, msgs, 2) == 2) { return RT_EOK; } else return -RT_ERROR;}static int8_t write_bme280_reg(uint8_t reg, uint8_t *data, uint16_t len){ rt_uint8_t tmp = reg; struct rt_i2c_msg msgs; msgs.addr= BME280_ADDR; /* Slave address */ msgs.flags = RT_I2C_WR; /* Write flag */ msgs.buf = &tmp; /* Slave register address */ msgs.len = 1; /* Number of bytes sent */ msgs.addr= BME280_ADDR; /* Slave address */ msgs.flags = RT_I2C_WR | RT_I2C_NO_START; /* Read flag */ msgs.buf = data; /* Read data pointer */ msgs.len = len; /* Number of bytes read */ if (rt_i2c_transfer(i2c_bus, msgs, 2) != 2) { return -RT_ERROR; } return RT_EOK;}static void readCalibrationData(){ uint8_t data; read_bme280_reg(0x88, data, 24); read_bme280_reg(0xa1, data + 24, 1); read_bme280_reg(0xe1, data + 25, 7); dig_T1 = (data
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