Look at the kernel source under tools/iio for examples on how to use IIO.
Regards,
John
> On Mar 27, 2018, at 12:10 PM, pierrick.ra...@gadz.org wrote:
>
> Hi John,
>
> Sorry for the late answer, I had hard time using the PRUs and I am now going
> to use the IIO ADC driver, I am able to read the sample with the cat command
> in /sys/bus/iio/devices/iio:device0/in_voltage3_raw
> However I am not able to use Libiio in order to read data from a user space
> application, I am reading (nil) instead of my data. Do you have any idea of
> where does the problem comes from ?
>
> Here is the code I am using in the user space :
>
>
> #define _BSD_SOURCE
> #define _GNU_SOURCE
> #define _DEFAULT_SOURCE
>
> #include <cdk/cdk.h>
> #include <locale.h>
> #include <pthread.h>
> #include <stdbool.h>
> #include <unistd.h>
> #include <stdint.h>
> #include <stdio.h>
> #include <string.h>
>
> #ifdef __APPLE__
> #include <iio/iio.h>
> #else
> #include <iio.h>
> #endif
>
> struct iio_context *ctx;
> struct iio_device *dev;
> struct iio_channel *ch;
>
> int main()
> {
> ctx = iio_create_default_context();
> dev = iio_context_get_device(ctx, 0);
> ch = iio_device_get_channel(dev, 3);
>
>
> iio_device_attr_write_longlong(dev, "sample_rate", 100);
> iio_channel_attr_write_double(ch, "scale", 1);
>
> iio_channel_enable(ch);
>
> char *a = iio_device_get_data(dev);
> printf("%p\n", a);
>
> iio_channel_disable(ch);
>
> return 0;
> }
>
> Thanks
>
> Pierrick
>
>
> Le lundi 26 février 2018 16:46:11 UTC-5, john3909 a écrit :
> The IIO ADC driver can run at 800K samples per second. Here is the patch that
> made that possible.
>
> https://patchwork.kernel.org/patch/9391487/
> <https://patchwork.kernel.org/patch/9391487/>
>
> I can confirm that I have tested the driver at 800Ksps and it works fine as
> long as you have a proper low impedance source for each ADC channel. CPU
> utilization was about 5% if I recall and that was probably used by the iiod
> daemon, which I used to display the waveform on a remote Linux app.
>
> There is example code in the original Starterware for McSPI, which should
> work fine if you are using the PRU low level drivers.
>
> Regards,
> John
>
>
>
>
>> On Feb 26, 2018, at 12:56 PM, pierric...@gadz.org <> wrote:
>>
>> Thanks John,
>>
>> I am now working with the starterware_PRU but i did not find examples for
>> using the McSPI with the PRU, do you think it will be hard to adapt the
>> initial code to the PRU ?
>> By the way, looking to the IIO driver documentation, it seems that for the
>> AM335x chip the max sampling rate is only 200k samples per second which may
>> not be enough :
>> http://processors.wiki.ti.com/index.php/Linux_Core_ADC_Users_Guide
>> <http://processors.wiki.ti.com/index.php/Linux_Core_ADC_Users_Guide> ; am I
>> right ?
>>
>>
>> Thanks
>>
>> Pierrick
>>
>> Le lundi 19 février 2018 23:15:50 UTC-5, john3909 a écrit :
>> Like I said, it was based on Starterware, so search Github for starterware
>> and you will see a project starterware_PRU. It does use the mcspi, so it is
>> not a bitbang implementation.
>>
>> Regards,
>> John
>>
>>
>>
>>
>>> On Feb 19, 2018, at 7:33 PM, pierric...@gadz.org <> wrote:
>>>
>>> Thanks John for you answer, I was quit busy last week so I worked on this
>>> during the Weekend.
>>>
>>> Unfortunately, I was not able to find a project that is using the SPI and
>>> I2C interface with the PRU, I only found this one :
>>> https://github.com/chanakya-vc/PRU-I2C_SPI_master/wiki/SPI-Master-Controller
>>>
>>> <https://github.com/chanakya-vc/PRU-I2C_SPI_master/wiki/SPI-Master-Controller>
>>>
>>> But it is using bit banging for the SPI part and not using the on-board
>>> pull-up resistors for the I2C part.
>>>
>>> Concerning the ADC, I'll have a loook at the UIIO drivers in the coming
>>> days it seems that it meets my need in term of real-time acquisition.
>>>
>>> Regards,
>>>
>>> Pierrick
>>>
>>> --
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