Re: [Flashforth-devel] A-D

[GRAHAM B. <gw...@bi...>]

David - many thanks - I had not picked up on the prescaler - the a-d's 
are now working. I have read pages 275 to 295 repeatedly but did not 
realise the need to set the prescaler. It is there very clearly when you 
know what to look for. Hard to get good help these days!!!!!!!!!!!!!!!!!!

Graham Boyd
Managing Director
Geosolutions Pty. Ltd.
16 Centre Way
Belair, 5052
South Australia
Ph. 61 (0)407 563944
     61 (0)8 82786752
www.geosol.com.au

On 3/19/2015 2:43 PM, David Schweizer wrote:
> I'm a rank beginner with both Forth and Atmel processors, but I hacked 
> and thrashed my way through to produce the four attached files that do 
> work (on an Arduino R3 with FlashForth).
>
> There's no good reason the code is spread over four files...
>
> --dls
>
>
> On Wed, Mar 18, 2015 at 8:55 PM, GRAHAM BOYD <gw...@bi... 
> <mailto:gw...@bi...>> wrote:
>
>     Mikael - sorry to bother you with this one, but I really do need
>     help from a higher source.
>
>     Attached is simple code designed to do an A-D on channel zero.
>     Only two registers need to be set (ADMUX,ADCSRA)with one (ADCSRB)
>     left at default.
>
>     I have 2.65 volts on AD0 with AREF at 5.01 measured with a
>     voltmeter. Before initialising A-D system $78 @ returns 0.
>
>     Set ADEN to 1. With no interrupt ADIF bit always set, resetting it
>     to zero and it immediately resets to 1. $78 @ returns 1023.
>     Settting ADSC bit appears to do nothing.
>
>     Setting interrupt and continuous interrupts occur. Again 1023
>     returned in the two data registers.
>
>     Setting  the BG voltage ref as input still returns 1023.
>
>     Can change voltage selection using REFS1, REFS0 as per the
>     documentation and it measures correctly at AREF with a voltmeter.
>
>     Same result with two different MEGA boards - so not a faulty board.
>
>     Have had great success so far with this Forth - keypad,lcd, GPS,
>     battery backed clock, SDHC/ micro SDHC all functioning so I am
>     rather surprised that someting as simple as an A-D conversion failing.
>
>     Many thanks - Graham
>
>     -- 
>     Graham Boyd
>     Managing Director
>     Geosolutions Pty. Ltd.
>     16 Centre Way
>     Belair, 5052
>     South Australia
>     Ph. 61 (0)407 563944
>         61 (0)8 82786752
>     www.geosol.com.au <http://www.geosol.com.au>
>
>
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