D6T-8L-09 support

[mKeRix]

Hey there,

I just got the Omron D6T-8L-09 sensor and have been using your library for playing around with it. Thanks for the great work!

In the d6t_open function of the d6t.c file your print a device not supported error for the D6T-8L-09 model. What's the reasoning behind this? I am able to receive data if I tell the lib that it is a D6T-8L-06 (however either my sensor is defective or the data is interpreted too high, e.g. 35 from sensor vs 21 in reality degrees).

[jmromeo]

Hey!

Originally I marked the D6T-8L-09 as unsupported because the application note (https://www.components.omron.com/documents/35730/96733/AN-D6T-01EN_r2.pdf/fb9c9fdd-4d2a-df6a-77b9-234c07be20a8) for the Omron sensors shows a slightly different temperature read flow. For all of the sensors I marked as supported, the code flow from the application note looks like so:

int D6T_getvalue()
{
	I2C_start();
	I2C_send1(0x14, 0x4C) 
	I2C_repeatstart();
	I2C_getx(0x15, readbuff, 35);
	I2C_stop();
	If(!D6T_checkPEC(readbuff,34)) 
	{
		return -1 ; / / error
	}
	tPTAT = 256 * readbuff[1] + readbuff[0];
	tP[0] = 256 * readbuff[3] + readbuff[2];
	tP[1] = 256 * readbuff[5] + readbuff[4];
	tP[2] = 256 * readbuff[7] + readbuff[6];
	tP[3] = 256 * readbuff[9] + readbuff[8];
	tP[4] = 256 * readbuff[11] + readbuff[10];
	tP[5] = 256 * readbuff[13] + readbuff[12];
	tP[6] = 256 * readbuff[15] + readbuff[14];
	tP[7] = 256 * readbuff[17] + readbuff[16];
	tP[8] = 256 * readbuff[19] + readbuff[18];
	tP[9] = 256 * readbuff[21] + readbuff[20];
	tP[10] = 256 * readbuff[23] + readbuff[22];
	tP[11] = 256 * readbuff[25] + readbuff[24];
	tP[12] = 256 * readbuff[27] + readbuff[26];
	tP[13] = 256 * readbuff[29] + readbuff[28];
	tP[14] = 256 * readbuff[31] + readbuff[30];
	tP[15] = 256 * readbuff[33] + readbuff[32];
	tPEC = readbuff[34];

	return 1; // success
}

The only changes for the different sensors is the buffer size used, and the number of temperature data values.

For the D6T-8L-09, it shows the following code:

int D6T_getvalue()
{
	 I2C_start();
	 I2C_send(0x14, 0x02, 0x00, 0x01, 0xEE) ;
	 I2C_stop();
	 I2C_start();
	 I2c_send(0x14, 0x05, 0x90, 0x3A, 0xB8);
	 I2C_stop();
	 I2C_start();
	 I2c_send(0x14, 0x03, 0x00, 0x03, 0x8B);
	 I2C_stop();
	 I2C_start();
	 I2c_send(0x14, 0x03, 0x00, 0x07, 0x97);
	 I2C_stop();
	 I2C_start();
	 I2c_send(0x14, 0x02, 0x00, 0x00, 0xE9);
	 I2C_stop();
	 I2C_start();
	 I2C_send(0x14, 0x02);
	 I2C_repeatstart();

	 I2C_send(0x15);
	 I2C_get(0x15, readbuff, 2); //Expected value of 2 byte read is 0x00 and 0x00.
	 I2C_stop();
	 I2C_start();
	 I2c_send(0x14, 0x05);
	 I2C_repeatstart();
	 I2C_send(0x15);
	 I2C_get(0x15, readbuff, 2); //Expected value of 2 byte read is 0x90 and 0x3A.
	 I2C_stop();
	 I2C_start();
	 I2C_send(0x14, 0x03);
	 I2C_repeatstart();
	 I2C_send(0x15);
	 I2C_get(0x15, readbuff, 2; //Expected value of 2 byte read is 0x00 and 0x07.
	 I2C_stop();
	 I2C_start();
	 I2C_send1(0x14, 0x4C); 
	 I2C_repeatstart();
	 I2C_getx(0x15, readbuff, 19);
	 I2C_stop();
	 If(!D6T_checkPEC(readbuff, 18))
	 {
	 	return -1; //error
	 }

	 tPTAT = 256 * readbuff[1] + readbuff[0];
	 tP[0] = 256 * readbuff[3] + readbuff[2];
	 tP[1] = 256 * readbuff[5] + readbuff[4];
	 tP[2] = 256 * readbuff[7] + readbuff[6];
	 tP[3] = 256 * readbuff[9] + readbuff[8];
	 tP[4] = 256 * readbuff[11] + readbuff[10];
	 tP[5] = 256 * readbuff[13] + readbuff[12];
	 tP[6] = 256 * readbuff[15] + readbuff[14];
	 tP[7] = 256 * readbuff[17] + readbuff[16];
	 tPEC = readbuff[18];   

	 return 1;
}

Note the additional startup sequence. As I didn't have a sensor to test on, I thought it would be easier to just mark as unsupported.

[jmromeo]

My guess is that the missing setup from the I2C writes is potentially causing the inaccurate temperature readings.

[mKeRix]

Thanks for the hints! I will try to investigate further using the code snippets above and possibly get back to you with a MR at some point.

[jmromeo]

Great! I added some untested code to branch here:

https://github.com/jmromeo/d6t/tree/feature/D6T-8L-09-Support

Unfortunately I don't have my beaglebone setup, or access to a D6T-8L-09 sensor to test it out and fix any mistakes made. Let me know how it goes and if you're able to get it working.

[mKeRix]

I tried your new code, but unfortunately it only returns 0 values for temperatures and 0x5f for pec now. Will try to dive deeper as I find the time! Thanks for the quick help :)

[jmromeo]

NP, good luck!

[mKeRix]

Another update: I tried the code on the BeagleBone, but now I'm only getting this:

Unable to send data: Bad file descriptor
Unable to send data: Bad file descriptor
Unable to send data: Bad file descriptor
Thermal Sensor Temperature: 0
1: 0
2: 4.9
3: 0
4: 453.6
5: 63.8
6: 1358.4
7: 4681.1
8: 1.6
pec: 0x0

Maybe I'll take another look at the lib code sometime, but as I got everything working with the D6T-44L-06 now this is more of a rainy day project.