介紹
MCXN947
NXP FRDM-MCXN947開發板是一款基於MCXN947 MCU的低成本評估板,MCU整合了雙核Arm Cortex-M33微控制器和一個神經處理單元(NPU)。開發板由一個MCXN947控制器和一個64 Mbit外部序列快閃記憶體組成。該板還具有P3T1755DP I3C溫度感測器,TJA1057GTK/3Z CAN PHY,乙太網PHY, SDHC電路(卡槽為DNP), RGB LED,觸控板,高速USB,按鈕,和MCU-Link除錯介面。該板相容Arduino遮蔽模組,Pmod板,mikroBUS。該板還支援攝像頭模組和NXP低成本LCD模組PAR-LCD-S035
開箱影片
我透過參過RT-Thread社群的活動,拿到了京東的包裹,板子的開箱影片:FRDM-MCXN947開發板開箱_嗶哩嗶哩_bilibili
開發環境
基本的開發資料有以下幾個,軟體包或者資料都可以在NXP官網、Keil的官網找到,插一句話,最近Keil免費了
- MDK531
- NXP.MCXN947_DFP.17.0.0
- rt_vsnprintf_full-latest.zip開發包
- 官方的文件:UM12018.pdf
- RT-Thread GitHub倉庫最新程式碼
開發環境搭建請參考影片:FRDM-MCXN947開發板開發環境上手_嗶哩嗶哩_bilibili
實驗目的
最近南方地區都在下暴雨,氣候悶熱潮溼,人們出門都在時刻關注天氣的變化情況;剛好這個時候RT-Thread社群給我送來一款包裝精緻的NXP開發板,讓我手頭上的BME280溫溼度氣壓感測器有了用武之地;BME280採用i2c介面和主機通訊,能實時監控室內、室外的溫度、溼度、大氣壓情況,基於它我們能做很多工業、物聯網、醫療、汽車方面的應用
實驗準備
我們需要準備以下材料
- NXP FRDM-MCXN947開發板
- 溫溼度氣壓模組BME280 (i2c介面)
- SSD1306 OLED模組(i2c介面)
- 公母頭杜邦線若干
模組電路
板載資源
本次實驗是透過軟體i2c + 硬體i2c方式來進行通訊,軟體i2c採用引腳P0_4 (SCL)和P0_5 (SDA) ,硬體i2c採用引腳P0_25 (SCL)和P0_24 (SDA),前者位於J9
內側的第8和第9引腳,後者位於J2
外側的第7和第5引腳,引腳圖參考如下,注意不要接錯
實物連線
軟體i2c口接OLED SSD1306模組,硬體i2c口接BME280模組,電源VCC和GND在J8和J6上面都有,千萬別接錯了!
程式設計
模組配置
克隆rt-thread官方倉庫的程式碼,MCXN947板子的最小例程在bsp\nxp\mcx\mcxn\frdm-mcxn947
目錄下
git clone https://github.com/RT-Thread/rt-thread.git
用RT-Thread Studio匯入frdm-mcxn947工程,然後開啟env工具
在env終端輸入命令menuconfig,配置rt-thread工程
在RT-Thread Components
下找到Device Drivers
並Select
進去,軟體i2c引腳配置如下
在Hardware Drivers Config
下找到On-chip Peripheral Drivers
並Select
進去,硬體i2c引腳配置如下
找到RT-Thread online packages
-> peripheral libraries and drivers
-> ssd1306
並Select
進去,配置SSD1306模組,記得改掉I2c bus name和開啟ssd1306的sample選項,這裡名稱為i2c2,和上面配置的軟體i2c名稱一致
配置完後透過Exit
退出,先更新軟體包,再匯出為mdk5工程,然後用Keil5開啟
pkgs --update
scons --target=mdk5
編譯工程
需要註釋一些程式碼確保編譯透過
ssd1306_tests.h
ssd1306.h
編碼整合
SSD1306
呼叫初始化介面並設定背景為黑色
ssd1306_Init();
ssd1306_Fill(Black);
繪圖介面示範,先往buffer裡邊填字串資料,然後設定座標,再繪製字元
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
用於讀取和校準BME280的資料
static unsigned long int hum_raw,temp_raw,pres_raw;
static rt_uint8_t data[8];
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_t dig_H1;
static int16_t dig_H2;
static int8_t dig_H3;
static int16_t dig_H4;
static int16_t dig_H5;
static int8_t dig_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[32];
read_bme280_reg(0x88, data, 24);
read_bme280_reg(0xa1, data + 24, 1);
read_bme280_reg(0xe1, data + 25, 7);
dig_T1 = (data[1] << 8) | data[0];
dig_T2 = (data[3] << 8) | data[2];
dig_T3 = (data[5] << 8) | data[4];
dig_P1 = (data[7] << 8) | data[6];
dig_P2 = (data[9] << 8) | data[8];
dig_P3 = (data[11]<< 8) | data[10];
dig_P4 = (data[13]<< 8) | data[12];
dig_P5 = (data[15]<< 8) | data[14];
dig_P6 = (data[17]<< 8) | data[16];
dig_P7 = (data[19]<< 8) | data[18];
dig_P8 = (data[21]<< 8) | data[20];
dig_P9 = (data[23]<< 8) | data[22];
dig_H1 = data[24];
dig_H2 = (data[26]<< 8) | data[25];
dig_H3 = data[27];
dig_H4 = (data[28]<< 4) | (0x0F & data[29]);
dig_H5 = (data[30] << 4) | ((data[29] >> 4) & 0x0F);
dig_H6 = data[31];
}
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讀寫介面封裝
static int read_bme280_reg(rt_uint8_t reg_addr, rt_uint8_t *data, rt_uint8_t len)
{
struct rt_i2c_msg msgs[2];
msgs[0].addr = BME280_ADDR;
msgs[0].flags = RT_I2C_WR;
msgs[0].buf = ®_addr;
msgs[0].len = 1;
msgs[1].addr = BME280_ADDR;
msgs[1].flags = RT_I2C_RD;
msgs[1].buf = data;
msgs[1].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[2];
msgs[0].addr = BME280_ADDR; /* Slave address */
msgs[0].flags = RT_I2C_WR; /* Write flag */
msgs[0].buf = &tmp; /* Slave register address */
msgs[0].len = 1; /* Number of bytes sent */
msgs[1].addr = BME280_ADDR; /* Slave address */
msgs[1].flags = RT_I2C_WR | RT_I2C_NO_START; /* Read flag */
msgs[1].buf = data; /* Read data pointer */
msgs[1].len = len; /* Number of bytes read */
if (rt_i2c_transfer(i2c_bus, msgs, 2) != 2)
{
return -RT_ERROR;
}
return RT_EOK;
}
init_bme280
用於初始化i2c裝置
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_t << 5) | (osrs_p << 2) | mode;
uint8_t config_reg = (t_sb << 5) | (filter << 2) | spi3w_en;
uint8_t ctrl_hum_reg = osrs_h;
write_bme280_reg(0xF2, &ctrl_hum_reg, 1);
write_bme280_reg(0xF4, &ctrl_meas_reg, 1);
write_bme280_reg(0xF5, &config_reg, 1);
readCalibrationData();
return RT_EOK;
}
將BME280的設定當作一條命令來執行
void run_bme280()
{
bme280_thread = rt_thread_create("bme280", bme280_entry, RT_NULL, 1024, 16, 20);
if(bme280_thread != RT_NULL)
{
rt_thread_startup(bme280_thread);
}
}
MSH_CMD_EXPORT(run_bme280, run bme280);
整合程式碼
以下程式碼經過測試,可以實現本次實驗的所有功能
#include <rtthread.h>
#include <rtdevice.h>
#include "ssd1306.h"
#define LED_PIN ((0*32)+10)
#define BME280_I2C_BUS_NAME "i2c1"
#define BME280_ADDR 0x76
#define SIZE 50
static struct rt_i2c_bus_device *i2c_bus;
static rt_thread_t bme280_thread = RT_NULL;
static unsigned long int hum_raw,temp_raw,pres_raw;
static rt_uint8_t data[8];
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_t dig_H1;
static int16_t dig_H2;
static int8_t dig_H3;
static int16_t dig_H4;
static int16_t dig_H5;
static int8_t dig_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 char buffer[SIZE];
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);
}
static int read_bme280_reg(rt_uint8_t reg_addr, rt_uint8_t *data, rt_uint8_t len)
{
struct rt_i2c_msg msgs[2];
msgs[0].addr = BME280_ADDR;
msgs[0].flags = RT_I2C_WR;
msgs[0].buf = ®_addr;
msgs[0].len = 1;
msgs[1].addr = BME280_ADDR;
msgs[1].flags = RT_I2C_RD;
msgs[1].buf = data;
msgs[1].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[2];
msgs[0].addr = BME280_ADDR; /* Slave address */
msgs[0].flags = RT_I2C_WR; /* Write flag */
msgs[0].buf = &tmp; /* Slave register address */
msgs[0].len = 1; /* Number of bytes sent */
msgs[1].addr = BME280_ADDR; /* Slave address */
msgs[1].flags = RT_I2C_WR | RT_I2C_NO_START; /* Read flag */
msgs[1].buf = data; /* Read data pointer */
msgs[1].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[32];
read_bme280_reg(0x88, data, 24);
read_bme280_reg(0xa1, data + 24, 1);
read_bme280_reg(0xe1, data + 25, 7);
dig_T1 = (data[1] << 8) | data[0];
dig_T2 = (data[3] << 8) | data[2];
dig_T3 = (data[5] << 8) | data[4];
dig_P1 = (data[7] << 8) | data[6];
dig_P2 = (data[9] << 8) | data[8];
dig_P3 = (data[11]<< 8) | data[10];
dig_P4 = (data[13]<< 8) | data[12];
dig_P5 = (data[15]<< 8) | data[14];
dig_P6 = (data[17]<< 8) | data[16];
dig_P7 = (data[19]<< 8) | data[18];
dig_P8 = (data[21]<< 8) | data[20];
dig_P9 = (data[23]<< 8) | data[22];
dig_H1 = data[24];
dig_H2 = (data[26]<< 8) | data[25];
dig_H3 = data[27];
dig_H4 = (data[28]<< 4) | (0x0F & data[29]);
dig_H5 = (data[30] << 4) | ((data[29] >> 4) & 0x0F);
dig_H6 = data[31];
}
static int init_bme280(void)
{
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_t << 5) | (osrs_p << 2) | mode;
uint8_t config_reg = (t_sb << 5) | (filter << 2) | spi3w_en;
uint8_t ctrl_hum_reg = osrs_h;
write_bme280_reg(0xF2, &ctrl_hum_reg, 1);
write_bme280_reg(0xF4, &ctrl_meas_reg, 1);
write_bme280_reg(0xF5, &config_reg, 1);
readCalibrationData();
return RT_EOK;
}
static void bme280_entry(void* paremeter)
{
init_bme280();
while(1)
{
read_bme280_reg(0xf7, data, 8);
pres_raw = (data[0] << 12) | (data[1] << 4) | (data[2] >> 4);
temp_raw = (data[3] << 12) | (data[4] << 4) | (data[5] >> 4);
hum_raw = (data[6] << 8) | data[7];
temp_cal = calibration_T(temp_raw);
press_cal = calibration_P(pres_raw);
hum_cal = calibration_H(hum_raw);
temp_act = (double)temp_cal / 100.0;
press_act = (double)press_cal;
hum_act = (double)hum_cal / 1024.0;
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);
rt_memset(buffer, SIZE, 0);
rt_snprintf(buffer, SIZE, "Humi : %d %\r\n",(int)hum_act);
ssd1306_SetCursor(2, 26 + 10);
ssd1306_WriteString(buffer, Font_6x8, White);
rt_memset(buffer, SIZE, 0);
rt_snprintf(buffer, SIZE, "Press : %d Pa\r\n",(int)press_act);
ssd1306_SetCursor(2, 26 + 10 + 10);
ssd1306_WriteString(buffer, Font_6x8, White);
rt_thread_mdelay(500);
ssd1306_UpdateScreen();
}
}
void run_bme280()
{
bme280_thread = rt_thread_create("bme280", bme280_entry, RT_NULL, 1024, 16, 20);
if(bme280_thread != RT_NULL)
{
rt_thread_startup(bme280_thread);
}
}
MSH_CMD_EXPORT(run_bme280, run bme280);
int main(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;
}
ssd1306_Init();
ssd1306_Fill(Black);
rt_pin_mode(LED_PIN, PIN_MODE_OUTPUT);
for (;;)
{
rt_pin_write(LED_PIN, PIN_HIGH);
rt_thread_mdelay(500);
rt_pin_write(LED_PIN, PIN_LOW);
rt_thread_mdelay(500);
}
}
實驗效果
用串列埠工具開啟開發板對應的串列埠,命令列輸入run_bme280
效果如下,OLED實時展示當前環境的溫度、溼度、大氣壓
總結
- 技術離不開應用、離不開生活,學習技術是為了更好的服務於社會
- NXP的硬體i2c比較複雜,官方的demo比較多、配置也複雜,理解起來確實有一點難度,我在用i2c-tool工具的時候遇到了一些問題,目前還在分析、定位中