On 07/05/2013 03:10 PM, Marek Vasut wrote:
Dear Hector Palacios,
Dear Marek,
On 07/05/2013 01:37 PM, Marek Vasut wrote:
Dear Hector Palacios,
The LRADC virtual channels have an 18 bit field to store the sum of up
to 2^5 accumulated samples. The read_raw function however only operates
over a single sample (12 bit resolution).
In order to use this field for scaling operations, we need it to be the
exact resolution value of the LRADC.
How would this work once the accumulation is supported?
As I see it, when you read a channel the driver should give you the 12-bit
value either of one single sample or of N samples.
The hardware will always give you 18 bit value, let's call it A of N accumulated
samples, each 12 bit long. N is in range of 1 to 32 .
The driver currently supports N = 1.
Do I understand it correctly that if we want to support N > 1, we have to do the
division of A / N in the driver and therefore we will again report only a 12-bit
value to the userland ?
If so,
Acked-by: Marek Vasut <marex@xxxxxxx>
That's what I would expect. I mean, what is A worth for? It's just a sum, it tells
nothing. The value that really carries information is A / N, which is the average value.
@Lars: is there any driver that allows to read N samples? Does the IIO subsystem
supply such interface (i.e. a file called n_samples that you can program from userland
to trigger a read of that N samples in order to get the average value when you read
that channel)?
Best regards,
--
Hector Palacios
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