“智慧光伏”項(xiàng)目能夠智能追蹤陽(yáng)光的移動(dòng)軌跡。通過(guò)內(nèi)置的光敏傳感器和智能控制系統(tǒng)，實(shí)時(shí)感知周?chē)庠吹淖兓Ⅱ?qū)動(dòng)太陽(yáng)能板精準(zhǔn)調(diào)整角度，確保每一縷陽(yáng)光都能被最大化地捕捉和利用。下面就和各位小伙伴詳細(xì)介紹一下這一開(kāi)源項(xiàng)目是怎樣實(shí)現(xiàn)的。

環(huán)境說(shuō)明

1.開(kāi)發(fā)環(huán)境操作系統(tǒng)：Ubuntu18.04 64位版

2.交叉編譯工具鏈：arm-poky-linux-gnueabi-gcc5.3.0

3.開(kāi)發(fā)板使用Bootloader版本：u-boot-2016.03

4.開(kāi)發(fā)板內(nèi)核版本：linux-4.1.15

5.開(kāi)發(fā)板移植QT版本：qt5.6.2

一、 硬件連接

1、四路光敏傳感器與板卡的連接

2、舵機(jī)與板卡的連接

二、內(nèi)核適配

1、實(shí)現(xiàn)舵機(jī)轉(zhuǎn)動(dòng)的功能

MG90S舵機(jī)采用pwm的方式來(lái)控制，該項(xiàng)目需要用到兩個(gè)舵機(jī)，所以需要在設(shè)備樹(shù)中進(jìn)行pwm7、pwm8的復(fù)用。

（1）拷貝ELF1開(kāi)發(fā)板資料包\02-Linux 源代碼\02-0 出廠內(nèi)核和uboot源碼\內(nèi)核源碼\linux-4.1.15-elf1.tar.bz2

內(nèi)核源碼到開(kāi)發(fā)環(huán)境/home/elf/work/目錄下解壓

elf@ubuntu:~/work$ tar -xvf linux-4.1.15-elf1.tar.bz2

（2）修改頂層設(shè)備樹(shù)文件arch/arm/boot/dts/imx6ull.dtsi

elf@ubuntu:~/work$ cd linux-4.1.15-elf1/ elf@ubuntu:~/work/linux-4.1.15-elf1$ vi arch/arm/boot/dts/imx6ull.dtsi

（3）修改設(shè)備樹(shù)文件arch/arm/boot/dts/imx6ull-elf1-emmc.dts

elf@ubuntu:~/work/linux-4.1.15-elf1$ vi arch/arm/boot/dts/imx6ull-elf1-emmc.dts

添加pwm7、pwm8設(shè)備節(jié)點(diǎn)

&pwm7 { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_pwm7>; status = "okay"; }; &pwm8 { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_pwm8>; status = "okay"; };

在iomux節(jié)點(diǎn)下面添加pwm7、pwm8引腳復(fù)用

pinctrl_pwm7: pwm7grp { fsl,pins = < MX6UL_PAD_CSI_VSYNC__PWM7_OUT 0x110b0 >; }; pinctrl_pwm8: pwm8grp { fsl,pins = < MX6UL_PAD_CSI_HSYNC__PWM8_OUT 0x110b0 >; };

取消其它用到csi功能的地方

至此pwm7、pwm8已經(jīng)復(fù)用完成

2、實(shí)現(xiàn)獲取光照值的功能

四路光敏傳感器需要四路adc，需要在設(shè)備樹(shù)中進(jìn)行adc1、adc2、adc3、adc4的復(fù)用

（1）修改設(shè)備樹(shù)文件arch/arm/boot/dts/imx6ull-elf1-emmc.dts

elf@ubuntu:~/work$ cd linux-4.1.15-elf1/ elf@ubuntu:~/work/linux-4.1.15-elf1$ vi arch/arm/boot/dts/imx6ull-elf1-emmc.dts

在iomux節(jié)點(diǎn)下面添加adc1、adc2、adc3、adc4引腳復(fù)用

pinctrl_adc1: adc1grp { fsl,pins = < MX6UL_PAD_GPIO1_IO05__GPIO1_IO05 0x00b0 MX6UL_PAD_GPIO1_IO01__GPIO1_IO01 0x00b0 MX6UL_PAD_GPIO1_IO02__GPIO1_IO02 0x00b0 MX6UL_PAD_GPIO1_IO03__GPIO1_IO03 0x00b0 MX6UL_PAD_GPIO1_IO04__GPIO1_IO04 0x00b0 >; };

注釋掉其它用到GPIO1_IO01、GPIO1_IO02、GPIO1_IO03、GPIO1_IO04功能的地方

至此adc已經(jīng)復(fù)用完成

3、編譯并替換設(shè)備樹(shù)

（1）執(zhí)行環(huán)境變量

elf@ubuntu:~/work/linux-4.1.15-elf1$ . /opt/fsl-imx-x11/4.1.15-2.0.0/environment-setup-cortexa7hf-neon-poky-linux-gnueabi

（2）編譯設(shè)備樹(shù)

elf@ubuntu:~/work/linux-4.1.15-elf1$ make imx6ull_elf1_defconfig elf@ubuntu:~/work/linux-4.1.15-elf1$ make dtbs

（3）將arch/arm/boot/dts/路徑下的imx6ull-elf1-emmc.dtb放到U盤(pán)，通過(guò)U盤(pán)拷貝到開(kāi)發(fā)板

root@ELF1:~# cp /run/media/sda1/imx6ull-elf1-emmc.dtb /run/media/mmcblk1p1/

（4）保存并重啟開(kāi)發(fā)板

root@ELF1:~# sync root@ELF1:~# reboot

三、數(shù)據(jù)采集和設(shè)備控制

1、程序設(shè)計(jì)

主函數(shù)的實(shí)現(xiàn)main.cpp

int main() { int up = 0; int down = 0; int left = 0; int right = 0; int duty_cycle6 = DUTY_90_DEG; int duty_cycle7 = DUTY_90_DEG; int adcChannels[] = {1, 2, 3, 4}; int adcValues[4] = {0}; init_pwm(); write_file(PWM6_DUTY_CYCLE, duty_cycle6); write_file(PWM7_DUTY_CYCLE, duty_cycle7); while (1) { for (int i = 0; i < 4; ++i) { adcValues[i] = read_adc_value(adcChannels[i]); } up = (adcValues[3] + adcValues[0]) ; down = (adcValues[2] + adcValues[1]) ; left = (adcValues[3] + adcValues[2]) ; right = (adcValues[0] + adcValues[1]) ; printf("up: %d\n", up); printf("down: %d\n", down); printf("left: %d\n", left); printf("right: %d\n", right); if ((down - up >= 200) && (duty_cycle6 >= DUTY_0_DEG)) { duty_cycle6 -= 100000; write_file(PWM6_DUTY_CYCLE, duty_cycle6); usleep(10000); } if ((up - down >= 200) && (duty_cycle6 <= DUTY_180_DEG)) { duty_cycle6 += 100000; write_file(PWM6_DUTY_CYCLE, duty_cycle6); usleep(10000); } if ((right - left >= 200) && (duty_cycle7 >= DUTY_0_DEG)) { duty_cycle7 -= 100000; write_file(PWM7_DUTY_CYCLE, duty_cycle7); usleep(10000); } if ((left - right >= 200) && (duty_cycle7 <= DUTY_180_DEG)) { duty_cycle7 += 100000; write_file(PWM7_DUTY_CYCLE, duty_cycle7); usleep(10000); } usleep(100000); } return 0; }

配置pwm

int init_pwm() { write_file(PWM6_EXPORT, 0); if (-1 == write_file(PWM6_PERIOD, PWM_PERIOD)) return -1; if (-1 == write_file(PWM6_ENABLE, 1)) return -1; write_file(PWM7_EXPORT, 0); if (-1 == write_file(PWM7_PERIOD, PWM_PERIOD)) return -1; if (-1 == write_file(PWM7_ENABLE, 1)) return -1; return 0; }

設(shè)置舵機(jī)初始位置

write_file(PWM6_DUTY_CYCLE, duty_cycle6); write_file(PWM7_DUTY_CYCLE, duty_cycle7);

獲取光照值

int read_adc_value(int adcNumber) { int adcValue = 0 ; FILE* adcFile; char adcValueFile[50]; char adcValueStr[10] = "0"; snprintf(adcValueFile, sizeof(adcValueFile), "/sys/bus/iio/devices/iio:device0/in_voltage%d_raw", adcNumber); adcFile = fopen(adcValueFile, "r"); if (adcFile) { fgets(adcValueStr, sizeof(adcValueStr), adcFile); adcValue = atoi(adcValueStr); fclose(adcFile); } else { fprintf(stderr, "Error opening ADC value file %s.\n", adcValueFile); } return adcValue; }

根據(jù)光照值調(diào)整舵機(jī)位置

if ((down - up >= 200) && (duty_cycle6 >= DUTY_0_DEG)) { duty_cycle6 -= 100000; write_file(PWM6_DUTY_CYCLE, duty_cycle6); usleep(10000); } if ((up - down >= 200) && (duty_cycle6 <= DUTY_180_DEG)) { duty_cycle6 += 100000; write_file(PWM6_DUTY_CYCLE, duty_cycle6); usleep(10000); } if ((right - left >= 200) && (duty_cycle7 >= DUTY_0_DEG)) { duty_cycle7 -= 100000; write_file(PWM7_DUTY_CYCLE, duty_cycle7); usleep(10000); } if ((left - right >= 200) && (duty_cycle7 <= DUTY_180_DEG)) { duty_cycle7 += 100000; write_file(PWM7_DUTY_CYCLE, duty_cycle7); usleep(10000); }

2、應(yīng)用編譯

（1）拷貝sun.tar.bz2到開(kāi)發(fā)環(huán)境/home/elf/work目錄下解壓

elf@ubuntu:~/work$ tar xvf sun.tar.bz2

（2）執(zhí)行環(huán)境變量

elf@ubuntu:~/work$ . /opt/fsl-imx-x11/4.1.15-2.0.0/environment-setup-cortexa7hf-neon-poky-linux-gnueabi

（3）編譯

elf@ubuntu:~/work$ cd sun/ elf@ubuntu:~/work/sun$ make

（4）拷貝sanapp到開(kāi)發(fā)板/home/root路徑下

root@ELF1:~# cp /run/media/sda1/sunapp ./ root@ELF1:~# sync

四、項(xiàng)目測(cè)試

1、確保開(kāi)發(fā)板已正確連接四路光敏傳感器和舵機(jī)

2、執(zhí)行應(yīng)用

root@ELF1:~# ./sunapp

此時(shí)可以打開(kāi)手電筒模擬太陽(yáng)光，調(diào)整太陽(yáng)能板的角度

對(duì)于初涉嵌入式開(kāi)發(fā)領(lǐng)域的小伙伴來(lái)說(shuō)，“智慧光伏”無(wú)疑是一個(gè)兼具趣味與實(shí)踐的開(kāi)源項(xiàng)目。通過(guò)親身參與這一開(kāi)源項(xiàng)目的組裝與調(diào)試過(guò)程，可以直接接觸到真實(shí)的開(kāi)發(fā)環(huán)境、工具鏈和代碼庫(kù)，從而解決實(shí)際問(wèn)題，幫助初學(xué)者更快地成長(zhǎng)為合格的嵌入式開(kāi)發(fā)工程師