With device tree, name of the device may change to some form like “fc Below is an example of how to use this tool: An oscilloscope can be used to measure exact number of edges versus the exact number of samples provided by the ADC, to see the reliability. Below is an example of how to use this tool: This is why we need to setup a buffer and have an interface to read the data from, if we want to use the hardware trigger. Documentation for this Linux subsystem is available in the kernel source code directory: Just set it to true or false whether you want the pin corresponding to the external trigger multiplexed as trigger inputs or not.
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This feature is exposed by IIO through the following files: To achieve a better speed, we can increase the clock to 20 mHz, which is the maximum supported sample rate: To enable oversampling for two extra bit of data, we can configure: Once 50 edges happen, we should see all 50 results in bulk. Support for the hardware external trigger has been in kernel mainline since kernel 4.
However, some dummy example of how to ac the timer-counter-0 is attached to this page.
UsingSAMA5D2ADCDevice < Linux4SAM < TWiki
In either case, the conversion is started on rising edges. However, conversion time will take 4 times longer.
The pins for the two last channels won’t be multiplexed as ADC outputs, and the channels won’t be available in the driver. It could be either u for unsigned or s afc signed 10 is the number of relevant bits of information 16 is the actual number of bits used to store the datum 0 is the number of right shifts needed.
To check that ADC driver is correctly loaded: Channel 1 Channel 3 Sample 1 Without oversampling, the last 2 bits of data are always 0, thus if we shift to the right by 2 bits or divide the value by 4the obtained value is the same as before 12 bits, in range 0, To enable oversampling for one extra bit of data, we can configure: All material on this collaboration platform is the property of the contributing authors. In IIO context, the watermark is the point of length inside the buffer that once is reached, the buffer will start to throw results into userspace.
LinuxKernel_4_1 < Linux4SAM < TWiki
Depending on device tree configuration edge type, the trigger name will reflect the edge type that it detects. If a single edge is detected on the hardware trigger, we aec not see any conversion results.
With DMA activated, each conversion value is not transferred from memory to userspace, until the number of conversions reaches the watermark level.
The ADC will automatically do the 4 conversions. Just set it to true or false whether you want the af91 corresponding to the external trigger multiplexed as trigger inputs or not. Thus, all the conversion data has to be stored in some buffer, for later retrieval by the userspace.
Other terms and product names may be trademarks of others. Using DMA to carry data on hardware trigger buffer Starting from kernel 4.
If an edge is detected, the ADC will start the conversion on all the enabled channels.
Release 4.11 drivers/iio/adc/at91-sama5d2_adc.c
All material on this collaboration platform is the property of the contributing authors. You should also disable pull-up and pull-down to have coherent measurement when the PIO is not used by the ADC device.
kinux Reading this file should return you a weird looking string. Linux is no longer interrupted on each trigger, and the DMA will carry the data and notify only when the watermark is reached. An oscilloscope can be used to measure exact number of edges versus the exact number of samples provided by the ADC, to see the reliability. Example on how to setup the timer counters.
ADC Touch screen is disabled. First, load the driver: With device tree, name of the device may change to some form like “fc There is a slight ABI change with this support, from now on, reported data is always on 14 bits.