[Tinyos-help] ADC switch channel

[Jan Hauer]

On 10/11/06, R. Steve McKown <rsmckown at yahoo.com> wrote:
> Hi Jan,
> (and those looking for multi-channel ADC)
>
> On Wednesday 11 October 2006 07:14 am, Jan Hauer wrote:
> > what you want to do is possible with the msp430 ADC12, but it has not
> > been implemented, neither in TinyOS 1.x nor 2.x.
>
> I've been meaning to clean up a modification of the msp430 adc12 peripheral I
> put together to support sequence of channels and repeating sequence of
> channels, as covered in the msp430 family user guide.  The code is compatible
> with tinyos-2.x CVS devel branch from 2006-09-26 but doesn't implement the
> newer FastClient interface.
>
> This code works well but is lightly used.  It's being used to sample a 3-axis
> accelerometer at 30kSa/sec (10kSa/sec * 3 channels) as well as low-frequency
> sampling of a group of ADC inputs using 'standard' ADC interfaces (Read,
> ReadNow, ReadStream).
>
> The code changes the adc12 interface (Msp430Adc12.nc) and the configuration
> structure (msp430adc12_channel_config_t).  The former change is mostly hidden
> by updated adc client components; the latter change requires user code to
> update its component(s) containing configuration structure(s).
>
> I've included some Makefile snippets to show how to use this code without
> altering your /opt/tinyos-2.x tree, and some code snippets to show how it
> works.
>
> I've been meaning to open a dialog with you about how I could contribute to
> enhancing the standard peripheral code.  I would appreciate your thoughts.
>
> For those looking for multi-sequence conversions, this code should be workable
> for you in the mean time.  Please note this code is not likely to be plug and
> play for you, so I'd avoid it unless you are ready to dig in and tweak it to
> fit your version of TinyOS.  It shouldn't be too difficult.
>
> All the best
> Steve

I updated the msp430 ADC12 TinyOS 2.x code last Monday to include DMA
support and also did a couple of other changes (new HAL interface,
renaming, optimization...), so the code might not be compatible with
HEAD. TEP 101 is still not finalized, but I don't expect any major
changes to come. Since people seem interested in multi-channel
sampling, I'm going to check something in (hopefully) in the next few
days (for 2.x).

I have only glanced over your code, but my plan was to add a separate
interface Msp430Adc12MultipleChannel instead of extending the main
interface (this is the reason why the current interface is called
Msp430Adc12SingleChannel). I'm not sure about the union approach
(passing a pointer to a pointer is a litte contrary to traditional
TinyOS design patterns :)), but maybe I can integrate some of your
code in the new version - I have to check and will talk to you
(offline).

Jan