TCS34725_DRIVER

• NAME: Nguyen Thanh Danh
• StudentID: 22146282
• NAME: Tran Xuan Hoang
• StudentID: 22146311
• NAME: Tran Anh Tri
• StudentID: 22146427
• NAME: Nguyen Huynh Anh
• StudentID: 22146263

OVERVIEW

TCS34725 RGB color sensor.

This driver ioctrl provide function in user space to get data in kernel.

Using I2C driver and register a I2C device tree.

INSTALL

Register a driver will create a character device at /dev/tcs34725. One more thing you have to do is register I2C device name "tcs34725@29" in I2C device tree.

DEVICE CLIENT

1. To register a device in device tree, let change directory to the boot

Change a dtb file to load a file when Raspberry starting and boot a I2C devide add a client.

I use a Raspberry Pi 4B so the dtb file is bcm2711-rpi-4-b.dtb.

Dtb is Device tree binray, so transfer it into dts to edit.

	cd /boot
	dtc -I dtb -O dts -o bcm2711-rpi-4-b.dts bcm2711-rpi-4-b.dtb
	sudo geany	

2. After that, edit bcm2711-rpi-4-b.dts with the sudo permission

In that case, i use geany to find a character easy.

The I2C we use in Raspberry is I2C1, then we find a code just like.

	&i2c1 {
        	compatible = "<name>";
        	status	= "disable";
	};

3. Add the client using I2C, repeat if u have any driver running base on I2C in the future

	&i2c1 {
        	compatible = "<name>";
        	status	= "okay";
		tcs34725@29 {
        		compatible = "tcs34725";
        		reg = <0x29>;
	};

Remember to change status to okay.

reg is a address of sensor in I2C protocol.

compatible to set Raspberry recognize sensor when it binding in to I2C bus

4. Then save a dts file, change it back to dtb file and reboot a Raspberry

	dtc -I dts -O dtb -o bcm2711-rpi-4-b.dtb bcm2711-rpi-4-b.dts
	sudo reboot

INSTALL DRIVER

1. Make sure the Makefile have a correct driver name you want to compile in obj-m += name.o

	obj-m += TCS34725_Driver_ioctrl.o
	KDIR = /lib/modules/$(shell uname -r)/build
	
	all:
		make -C $(KDIR) M=$(shell pwd) modules
	clean: 
		make -C $(KDIR) M=$(shell pwd) clean

<uname -r> give a kernel name is running, and certainly it have a build file

If it doesn't have, you should change a kernel version have a build file.

2. Build a .ko file using cmd

	make

3. Install a driver

	sudo insmod TCS34725_Driver_ioctrl.ko

In that case TCS34725_Driver_ioctrl are set in Makefile.

4. You can check a notice in kernel log file

	dmesg

5. If you want to uninstall driver run this cmd

	sudo rmmod TCS34725_Driver_ioctrl.ko

6. Then remove all file compile

	make clean

FUNCTION PROVIDE

CHARACTER DEVICE API

1. open(), close()

   Standard open() and close() operations on /dev/tcs34725 are supported.

2. read()

   Currently not implemented. Use ioctl() to get color data.

3. ioctl()
   #define TCS34725_IOC_MAGIC 't'
   #define TCS34725_GET_CLEAR   _IOR(TCS34725_IOC_MAGIC, 1, int)
   #define TCS34725_GET_RED     _IOR(TCS34725_IOC_MAGIC, 2, int)
   #define TCS34725_GET_GREEN   _IOR(TCS34725_IOC_MAGIC, 3, int)
   #define TCS34725_GET_BLUE    _IOR(TCS34725_IOC_MAGIC, 4, int)
   #define TCS34725_IOCTL_SET_GAIN    _IOW(TCS34725_IOCTL_MAGIC, 5, int)
   #define TCS34725_IOCTL_SET_ATIME   _IOW(TCS34725_IOCTL_MAGIC, 6, int)

Example:

	int fd;
	fd = open(DEVICE_NAME, O_RDWR);
	if (fd < 0) {
        	perror("Failed to open the device");
        	return errno;
	}
       	if (ioctl(fd, TCS34725_IOCTL_READ_C, &color_data) < 0) {
        	perror("Failed to read Clear Color Data");    
        	close(fd);
        	return errno;
    	} 
    	else {
        	printf("Read Clear Color Data: %d ", color_data);
    	}
   	close(fd);

TCS34725_GET_CLEAR is get the intensity all color.

TCS34725_GET_RED is get the intensity of RED.

TCS34725_GET_GREEN is get the intensity of GREEN.

TCS34725_GET_BLUE is get the intensity of BLUE.

Every color in range of 16 bit data.

TCS34725_IOCTL_SET_GAIN is set the sensitivity of sensor.

Gain is setting the sensor sensitivity: 0x00, 0x01, 0x02, 0x03 equal to 1x 4x 16x 60x.

TCS34725_IOCTL_SET_ATIM is set the integrate time for sensor

integration time = (256 - atime ) *2.4, short time get data quick, long time more accurate.

TEST DRIVER IN KERNEL

1. The Makefile change a obj-m to driver file

	obj-m += TCS34725_driver.o
	
	all:
		make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
	
	clean:
		make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

Then do the same.

2. Build a .ko file using cmd

	make

3. Install a driver

	sudo insmod TCS34725_Driver.ko

In that case TCS34725_Driver are set in Makefile.

4. You can check a notice in kernel log file

	dmesg

If running, the log file send a data get 1 time in sensor.

If no data is sending, check the I2C recognize a sensor before.

	i2cdetect -y 1

5. If you want to uninstall driver run this cmd

	sudo rmmod TCS34725_Driver.ko

6. Then remove all file compile

	make clean