Editing Instrument control package
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To work out the devices available (assuming i2ctools are installed) run the i2cdetect command from a terminal window. | To work out the devices available (assuming i2ctools are installed) run the i2cdetect command from a terminal window. | ||
$ i2cdetect -l | $ i2cdetect -l | ||
i2c-1 i2c i2c-ch341-usb at bus 002 device 008 I2C adapter | i2c-1 i2c i2c-ch341-usb at bus 002 device 008 I2C adapter | ||
i2c-0 unknown SMBus I801 adapter at 4000 N/ | i2c-0 unknown SMBus I801 adapter at 4000 N/ | ||
In the example case the temperature sensor is connected to the i2c-ch341-usb device, | In the example case the temperature sensor is connected to the i2c-ch341-usb device, as as sufficient permissions to access the device as a user. | ||
Accoridng to the datasheet, the temperature device uses address 0x40, so create a i2c device using the linux device and address: | |||
i2cdev = i2c("/dev/i2c-1", 0x40) | i2cdev = i2c("/dev/i2c-1", 0x40) | ||
To read the | To read the termaturem register 0xF3 must be addressed and read (2 bytes of data): | ||
TEMP_MEASURE_NOHOLD = hex2dec("F3"); | TEMP_MEASURE_NOHOLD = hex2dec("F3"); | ||
fwrite (i2cdev, uint8([TEMP_MEASURE_NOHOLD])); | fwrite (i2cdev, uint8([TEMP_MEASURE_NOHOLD])); | ||
pause (0.02); | pause (0.02); | ||
data = fread (i2cdev, 3); | data = fread (i2cdev, 3); | ||
The data | The data needs to be converted to a 16 bit value and the unused part masked out. | ||
value = uint16(data(1))*256 + uint16(data(2)); | value = uint16(data(1))*256 + uint16(data(2)); | ||
value = bitand (value, hex2dec("FFFC")); | value = bitand (value, hex2dec("FFFC")); | ||
temp_Code = double(value); | temp_Code = double(value); | ||
Now convert the temperature to degrees C and display: | Now convert the temperature to degrees C and display: | ||
C = (175.72*temp_Code/65536)-46.85; | C = (175.72*temp_Code/65536)-46.85; | ||
printf ("temperature read %f C\n", C); | printf ("temperature read %f C\n", C); | ||
== TCP == | == TCP == |