Re: [myhdl-list] *** GMX Spamverdacht *** Re: *** GMX Spamverdacht *** Re: *** GMX Spamverdacht *** Hello World

[Günther S. <gue...@gm...>]

Hello Josy,
thank you.
yes i saw that in VHDL there was this error.
Therefore i tried it with verilog.
But what i really do not understand what you mean you
do not use read at all.
Can you please explain this to me?
When i have this:

I2C_SDAT = TristateSignal(False)


How would i have to write it to avoid this and
how can i use this opendrain primitive than??


-- 
Regards
guenther




Am 17.05.2015 um 12:53 schrieb Josy Boelen:
> Günther Stangassinger <guenther.stangassinger <at> gmx.net> writes:
>
>> Hello,
>> it is working:
>> https://github.com/stangassinger/de0_nano_adxl345
>> I am getting the DEVID 0xE5
>> The problem was not the myhdl code.
>> The problem was the generated verilog code.
>> At the beginning of the generated code where the ports are declared
>> it says:
>> output I2C_SDAT;
>>
>> And this was one and only problem !!
>> Because the I2C_SDAT is tristate it should not be a output port.
>> There fore i changed it to:
>> inout I2C_SDAT;
>>
>> And with this change it is working
>>
>> But my question now is:
>> How do i have to declare the I2C_SDAT port in myhdl
>> so that it generates to "inout" ???
>>
>> I declared it with:
>>
>> I2C_SDAT = TristateSignal(False)
>>
>> What do i have to do the it generates this code:
>> inout I2C_SDAT;
>>
>> I would be very glad if someone could help me?
>> Thank you very much.
>> Best regards
>> guenther stangassinger
>>
> Hallo Günther,
>
> I converted your code to VHDL and there we get an *inout* for I2C_SDAT.
> But there is one error though:
> we get :             drive_spi_inst_read_Adr_inst_io <= (others => 'Z');
> where it should be:  drive_spi_inst_read_Adr_inst_io <= 'Z';
>
> I suggest you make an issue out of it as the conversion of
> TristateSignal doesn't look to be error-free.
>
> Personally I avoid (read: don't use at all) internal tristate signals:
> my I2C modules have a separate input and output signal for SDa, which I
> then drive to the SDa pin via an **opendrain** primitive in the toplevel
> file.
>
> Regards,
>
> Josy
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