View source for I.MX6UL internal ADC

== Introduction ==

This description uses Linux kernel >= 4.8.

i.MX6UL (processor of [[OPOS6UL]] has an integrated 12 bits 16 channels Analog to Digital Converter.

Only channels 0-6 may be used to generic conversions and channels 2, 3, 4, 5 are used for the touchscreen on [[OPOS6ULDev]].

* Channel 1 is available on J21 pin 40 of [[OPOS6ULDev]] (AIN1/YNLR: muxed with touchscreen)
* Channel 2 is available on J21 pin 38 of [[OPOS6ULDev]] (AIN2/YPLL: muxed with touchscreen)
* Channel 3 is available on J21 pin 39 of [[OPOS6ULDev]] (AIN3/XNUR: muxed with touchscreen)
* Channel 4 is available on J21 pin 37 of [[OPOS6ULDev]] (AIN4/XPUL: muxed with touchscreen)
* Channel 8 is available on J3 pin 12 of [[OPOS6ULDev]] (AIN8)
* Channel 9 is available on J3 pin  7 of [[OPOS6ULDev]] (AIN9)

== Driver ==
Driver is by default included if you choose an [[OPOS6UL]] as target.

Otherwise, you can select it that way:

<pre class="host">
[  ] $ make linux-menuconfig
</pre>

<pre class="config">
Device Drivers  --->
    ...
    <*> Industrial I/O support  --->
            ...
            Analog to digital converters
                ...
                <*> Freescale vf610 ADC driver
</pre>

Then compile the distribution :
<pre class="host">
[  ] $ make linux && make
</pre>

== Use it ==

=== Read channels value ===

<pre class="apf">
# cd /sys/bus/iio/devices/iio:device0
# ls
buffer                         in_voltage5_raw
current_timestamp_clock        in_voltage6_raw
dev                            in_voltage7_raw
in_conversion_mode             in_voltage8_raw
in_temp_input                  in_voltage9_raw
in_voltage0_raw                in_voltage_sampling_frequency
in_voltage10_raw               in_voltage_scale
in_voltage11_raw               name
in_voltage12_raw               of_node
in_voltage13_raw               power
in_voltage14_raw               sampling_frequency_available
in_voltage15_raw               scan_elements
in_voltage1_raw                subsystem
in_voltage2_raw                trigger
in_voltage3_raw                uevent
in_voltage4_raw
</pre>

To read ADC value just «cat» the corresponding input file:
<pre class="apf">
# cat in_voltage1_raw       for channel 1 (ADC1_IN1)
4095
</pre>

All values are not converted (ie. directly show the register content). To have the mV value, you must do: value_mV = read_value * 3300/4095

==AsDevices==
* You can access this device from your C/C++ application using ''as_adc_xxx_iio'' functions from [[AsDevices]]
* ''target/demos/oscillo'' is a "good" example to start with...

==Links==
* http://www.at91.com/linux4sam/bin/view/Linux4SAM/IioAdcDriver

[[Category:Linux drivers]]
[[Category:Analog to Digital Converter]]
[[Category:Industrial Input Output]]