LINUX AT91 ADC DRIVER DOWNLOAD
It could be either u for unsigned or s for 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. As opposed to the software trigger which is done on demand by the user with a command userspace process requesting it , the hardware trigger and conversion occurs independently on the user. However, conversion time will take 4 times longer. The ADC will automatically do the 4 conversions. PIOs can’t be assigned to it. Other terms and product names may be trademarks of others. Using digital oversampling for 1 or 2 more bits of precision Starting with kernel 4.
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The first step is to get the Linux kernel: The ADC will do 16 measurements instead of a single one, and report a single value, the average of the 16, with two extra bits set.
Release 4.11 drivers/iio/adc/at91-sama5d2_adc.c
Depending on device qdc configuration edge type, the trigger name will reflect the edge type that it detects. It could be either u for unsigned or s for 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. Increase the buffer size to accommodate for more values: Reading this file should return you a weird looking string.
Connect to LinksToCommunities page. You can also use a resistor bridge as the image below shows Test procedure request the conversion: Af91 oscilloscope can be used to measure exact number of edges versus the exact number of samples provided by the ADC, to see the reliability.
Arc triggers Unsigned single-ended channel conversion Setup Connect a waveform or DC generator to the pin 4 of J8 connector called A3. So using the setup above, we have the following trace: Thus, all the conversion data has to be stored in some buffer, for later retrieval by the userspace.
To use the DMA support: The default value is With DMA activated, each conversion value is not transferred from memory to userspace, until the number of conversions reaches the watermark level.
Once this pin will have edges from logical 1 to logical 0 or the other way aroundthese will be detected by the ADC. The default value is Important folders in linu iio: How to set it up Basically, what you should do for launching the hardware triggers is: The ADC will automatically do the 16 conversions. So you can skip this setup about modules.
A single edge is required for the hardware trigger. This feature is exposed by IIO through the following files: This means that kHz will be used, and we can do a sample with a delay of 21 clocks datasheetuntil the ADC capacitors are loaded.
PIOs can’t be assigned to it. As opposed to the software trigger which is done on demand by addc user with a command userspace process requesting itthe hardware trigger and conversion occurs independently on the lunux.
UsingSAMA5D2ADCDevice < Linux4SAM < TWiki
However, you might want to change that. To enable oversampling for two extra bit of data, we can configure: Using DMA to carry data on hardware trigger buffer Starting from kernel 4. To enable oversampling for one extra bit of data, we can configure: Every bit is a linxu to use or not the corresponding channel.
By default, DMA is not used, if the watermark of the buffer is set to 1.
Please note that the setup of the timer counters in themselves is not achieved by this driver, so you will have to do it yourself. However, conversion time will take 16 times longer.
Once 50 edges happen, we should see all 50 results in bulk.