Hi Paul, I didn't read all of your text (will do later), but would like to point out that there is alreay a project going on here: http://sourceforge.net/projects/iioutils/ You're very welcome to contribute. Regards, Manuel Stahl Am Montag, 3. März 2014, 12:31:46 schrieb Paul Cercueil: > Hi there, > > I would like to present the project I've been working on for the past > two weeks: libiio, a library for interfacing IIO devices. > Available here: https://github.com/analogdevicesinc/libiio > > As it is still in its infancy, I would like to receive feedback about > the API, what is good, what would you change etc. > > The API provides a couple of top-level functions to create a context, > either bound to the local IIO devices through sysfs, to a XML > representation, or to a remote server. This context structure (struct > iio_context) contains a list of devices and the context-specific > low-level operations to interact with them. > > From the context structure it is possible to retrieve the structures > representing the devices (struct iio_device). Devices have an ID, a > name, attributes and channels. > > Attributes essentially correspond to files in sysfs. For instance, the > attribute "sampling_frequency" of the device with the ID "iio:device0" > matches the file "/sys/bus/iio/devices/iio:device0/sampling_frequency". > The API provides functions to read or write attributes. > > Channels (struct iio_channel) represent a measure channel of a ADC or a > control channel of an DAC. In the local context, the channels are > deduced from the filenames in sysfs. For example, the file > "out_voltage0_vccout_offset" translates to an output channel with ID > "voltage0", name "vccout" featuring an attribute named "offset". > > The following sysfs files, for instance, would create the following tree: > > root:/> ls -1 -p /sys/bus/iio/devices/iio:device0 > buffer/ > dev > ... > in_magn_filter_low_pass_3db_frequency > in_magn_scale > in_magn_x_raw > in_magn_y_raw > in_magn_z_raw > name > power/ > sampling_frequency > scan_elements/ > subsystem > trigger/ > uevent > > --- > > IIO context has 1 devices: > iio:device0: adis16488 > 11 channels found: > ... > magn_x: (input) > 4 channel-specific attributes found: > attr 0: calibbias > attr 1: filter_low_pass_3db_frequency > attr 2: raw > attr 3: scale > magn_y: (input) > 4 channel-specific attributes found: > attr 0: calibbias > attr 1: filter_low_pass_3db_frequency > attr 2: raw > attr 3: scale > magn_z: (input) > 4 channel-specific attributes found: > attr 0: calibbias > attr 1: filter_low_pass_3db_frequency > attr 2: raw > attr 3: scale > 1 device-specific attributes found: > attr 0: sampling_frequency > > --- > > The API provides ways to read and write a stream of values. Either the > raw stream (basically reading/writing the dev node directly), or a > processed stream, corresponding to a single channel, with an optional > conversion step. In this case, the conversion is automatically deduced > from the attributes, notably the "scale" attribute. > > One recurring issue when working with IIO devices, is that only one > application can use an IIO device at a time. I intend to address that > issue by developping a network daemon (called iiod, that's original) > that would use the local backend of the libiio library, and stream the > data from/to a device from/to all of its connected clients. The clients > would then just be applications compiled with the libiio library, and > using the network backend of the library (note that switching between > backends is just a matter of creating the iio_context structure with a > different function). Once that works, a specific daemon / libiio backend > couple could be designed using fast SHM mechanism for high-speed > concurrent local access to the devices. > > As I may be overseeing certain things or missing others, I would like to > know what is your opinion of the API and the library so far, and if you > would use such a library. The feedback is important to me so that the > project moves in the right direction. > > Thanks, > > Paul > > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
