Add IIO example to the kernelnewbies wiki
Daniel Baluta
daniel.baluta at gmail.com
Wed May 9 03:21:08 EDT 2018
Sure, you can do that. Nice to see that you are using Diolan DLN-2 adapter.
thanks,
Daniel.
On Mon, Apr 2, 2018 at 8:06 PM, Gaston Gonzalez <gascoar at gmail.com> wrote:
> Hi,
>
> I'm testing an AD7746 eval board using a Diolan DLN-2 adapter. I wrote
> some basic notes about the installation an instanciation process for my
> own use. But then I thought it could be useful for someone else. So
> maybe I could put this in the kernel newbies page under the IIO section?
>
> If you think is worth it, I would be glad to add it to the wiki page.
>
> Best regards,
>
> Gaston
>
> Notes:
>
> The setup
> =========
>
> AD7746-EVAL BOARD --> Diolan DLN-2 Adapter --> Thinkpad T430
>
> The connection between the AD7746 eval board and adapter is as detailed
> in [2] I2C Interface Configuration Options, External connection (pag 4).
>
> The connection between Diolan DLN-2 and the T430 is USB straighforward.
>
> Drivers
> =======
>
> Both in mainline kernel:
>
> - Diolan DLN-2 driver: I2C_DLN2 (prompt Diolan DLN-2 USB I2C adapter)
> Loc: drivers/i2c/busses/
> - AD7746: AD7746
> Loc: drivers/staging/iio/cdc/
>
> Bus of interest
> ===============
>
> $ sudo i2cdetect -l
>
> We get something like:
>
> ...
> i2c-10 i2c dln2-i2c-1-1.2:1.0-0 I2C adapter
> ...
>
> So our bus is the number 10.
>
> Getting the address
> ===================
>
> $ sudo i2cdetect -y -r 10
>
> We get something like:
>
> 0 1 2 3 4 5 6 7 8 9 a b c d e f
> 00: -- -- -- -- -- -- -- -- -- -- -- -- --
> 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 40: -- -- -- -- -- -- -- -- 48 -- -- -- -- -- -- --
> 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 70: -- -- -- -- -- -- -- --
>
> 3. Device instantiation:
>
> # echo add7746 0x48 > /sys/bus/i2c/devices/i2c-10/new_device
>
> We must see something like:
>
> $ cd /sys/bus/i2c/devices/i2c-10/10-0048/
> $ ls
> driver iio:device0 modalias name power subsystem uevent
>
> $ cd iio:device0
> $ ls
> dev in_capacitance-capacitance_calibbias
> in_capacitance0_calibbias_calibration in_capacitance-capacitance_sampling_frequency
> in_capacitance0_calibscale in_capacitance-capacitance_scale
> in_capacitance0_calibscale_calibration in_capacitance_sampling_frequency
> in_capacitance0-capacitance2_calibscale in_capacitance_sampling_frequency_available
> in_capacitance0-capacitance2_offset in_capacitance_scale
> in_capacitance0-capacitance2_raw in_temp0_input
> in_capacitance0_offset in_temp1_input
> in_capacitance0_raw in_voltage0_calibscale_calibration
> in_capacitance1_calibbias_calibration in_voltage0_raw
> in_capacitance1_calibscale in_voltage1_supply_raw
> in_capacitance1_calibscale_calibration in_voltage_sampling_frequency
> in_capacitance1-capacitance3_calibscale in_voltage_sampling_frequency_available
> in_capacitance1-capacitance3_offset in_voltage_scale
> in_capacitance1-capacitance3_raw name
> in_capacitance1_offset power
> in_capacitance1_raw subsystem
> in_capacitance_calibbias uevent
>
> Checking the permits:
>
> $ ll
> -r--r--r-- 1 root root 4096 mar 31 09:57 dev
> --w------- 1 root root 4096 mar 31 09:57 in_capacitance0_calibbias_calibration
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance0_calibscale
> --w------- 1 root root 4096 mar 31 09:57 in_capacitance0_calibscale_calibration
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance0-capacitance2_calibscale
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance0-capacitance2_offset
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance0-capacitance2_raw
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance0_offset
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance0_raw
> --w------- 1 root root 4096 mar 31 09:57 in_capacitance1_calibbias_calibration
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance1_calibscale
> --w------- 1 root root 4096 mar 31 09:57 in_capacitance1_calibscale_calibration
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance1-capacitance3_calibscale
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance1-capacitance3_offset
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance1-capacitance3_raw
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance1_offset
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance1_raw
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance_calibbias
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance-capacitance_calibbias
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance-capacitance_sampling_frequency
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance-capacitance_scale
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance_sampling_frequency
> -r--r--r-- 1 root root 4096 mar 31 09:57 in_capacitance_sampling_frequency_available
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance_scale
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_temp0_input
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_temp1_input
> --w------- 1 root root 4096 mar 31 09:57 in_voltage0_calibscale_calibration
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_voltage0_raw
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_voltage1_supply_raw
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_voltage_sampling_frequency
> -r--r--r-- 1 root root 4096 mar 31 09:57 in_voltage_sampling_frequency_available
> -rw-r--r-- 1 root root 4096 mar 31 09:57 in_voltage_scale
> -r--r--r-- 1 root root 4096 mar 31 09:57 name
> drwxr-xr-x 2 root root 0 mar 31 09:57 power
> lrwxrwxrwx 1 root root 0 mar 31 09:57 subsystem -> ../../../../../../../../../../../bus/iio
> -rw-r--r-- 1 root root 4096 mar 31 09:57 uevent
>
> 4. Capacitance
>
> According to [2], the capacitive length sensor is connected to CIN2+ and
> CIN2-. In the driver, the values are mapped to capacitance0.
>
> Raw values vs sensor length:
>
> Note: (+) values means the sensor was moved to the left, (-) values
> means the sensor was moved to the right. I.e. +1 cm means the rule was
> moved 1 to the left, while -1 means the rule was moved 1 cm to the
> right.
>
> Note2: note the raw value for -10 is 8224733, while +10 is -8224726, the
> difference is because when the rule is moved 10 cm to the left, the is
> still 2 o 3 cm of dielectric between the plates. The design is obviously
> thought to move the rule to the right.
>
>
> Length (cm) | Raw Value Cap0
> ------------------------------
> -10 -8224733
> -9 -8224730
> -8 -8224728
> -7 -8224725
> -6 -8224724
> -5 -8224722
> -4 -8224720
> -3 -8224718
> -2 -8224716
> -1 -8224714
> +0 -8224711
> +1 -8224711
> +2 -8224711
> +3 -8224711
> +4 -8224713
> +5 -8224715
> +6 -8224717
> +7 -8224719
> +8 -8224721
> +9 -8224723
> +10 -8224726
>
>
> References
> ==========
>
> [1] http://www.analog.com/media/en/technical-documentation/data-sheets/AD7745_7746.pdf
> [2] http://www.analog.com/media/en/technical-documentation/evaluation-documentation/EVAL-AD7746EB.PDF
> [3] https://i2c.wiki.kernel.org/index.php/Main_Page
> [4] https://kernelsense.wordpress.com/2016/01/22/achievement-unlocked-first-iio-driver/
>
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