Hi Jan,
On 06/02/2012 07:33 PM, Jan Kromhout wrote:
> Dear Erich,
> I have done what you wrote, seems to work.
Very good!
> But when I look to te code of twi.frt I see
> some strange thing, or missing sommething.
> When I look into the code never is sending
> the address in twi.start \ send start condition
> : twi.start ( -- )
> [ 1 7 lshift
> 1 5 lshift or
> 1 2 lshift or ] literal
> TWCR c!
> twi.wait
> ;
>
> Where should I put the address?
The address is just the first byte to be transfered.
I use the following functions to send/receive n Byte to/from
some address. Feel free to recycle them:
\ send n bytes to addr
: >i2c ( x1 .. xN.msB N addr -- )
twi.start
twi.tx \ uses addr
0 do \ uses N
twi.tx \ uses xN .. x1
loop
twi.stop
;
: <i2c ( N addr -- xN.msB .. x1 )
twi.start
1+ twi.tx \ uses addr
1- dup 0 > if
0 do twi.rx loop
else
drop
then
twi.rxn
twi.stop
;
As you can see, the first call to twi.tx sends the addr.
If you have not downloaded the datasheet of your controller
from atmel.com, please do so. I know, these datasheets are
rather intimidating at first, however, they do include a lot
of information, e.g. how to set the bits in TWCR and their
meaning. I strongly suggest to consult the datasheet often.
You will learn to read it. And amforth will let you access
the registers and bits easily.
Cheers,
Erich
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