amforth-devel

[Amforth] <i2c function

[craig a. h. <ca...@gm...>]

In the function <i2c the code begins with
twi.start
1+ twi.tx
1- dup 0 >

Is the 1+ a typo? If not I do not understand why you would add one to the
hardware address before sending it out.

Please enlighten me

Thanks



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Re: [Amforth] <i2c function

[Matthias T. <mt...@we...>]

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Hi Craig,

> In the function <i2c the code begins with twi.start 1+ twi.tx 1-
> dup 0 >
> 
> Is the 1+ a typo? If not I do not understand why you would add one
> to the hardware address before sending it out.

This is the way some (most?, all?) i2c devices distinguish between read
and write access. The datasheet for your i2c device should tell you the
details

Matthias

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Re: [Amforth] <i2c function

[Michael P. <mp...@rc...>]

Having been through this exercise with I2C, let me confirm what Matthias
has stated.

The address sent to the device contains a 1 for WRITE; 0 for READ in the
least significant bit position.

Regards,

Michael
K6MLE


On 11/21/2013 10:49 PM, Matthias Trute wrote:
> Hi Craig,
>
> > In the function <i2c the code begins with twi.start 1+ twi.tx 1-
> > dup 0 >
>
> > Is the 1+ a typo? If not I do not understand why you would add one
> > to the hardware address before sending it out.
>
> This is the way some (most?, all?) i2c devices distinguish between read
> and write access. The datasheet for your i2c device should tell you the
> details
>
> Matthias
>
>
>
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