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

[Günther S. <gue...@gm...>]

Hello Josy,
thank you for your answer.
My problem is that i have to modify the generated verilog(vhdl) code to 
make it work.
Is myhdl meant to be like this or do i just have bad luck with this example?
I am asking because i am very new to myhdl and this is
acually my second example what i was trying.
Are you doing large projects with myhdl?
I am asking because i want to know if i should
dig more into myhdl or should i focus more on vhdl, when i do have
to modify vhdl afterwards anyway.
So what is your experiance?

-- 
Regards
guenther






Am 17.05.2015 um 20:13 schrieb Josy Boelen:
> Günther Stangassinger <guenther.stangassinger <at> gmx.net> writes:
>
>> 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??
>>
> Hello Günther,
>
> The one essential part of my answer was that the conversion of
> TristateSignal() seems to be incorrect, both for Verilog and VHDL.
> Also the VHDL conversion gives quite a few warnings:
> ** ToVHDLWarning: Output port is read internally: G_SENSOR_CS_N
> ** ToVHDLWarning: Port is not used: G_SENSOR_INT
> ** ToVHDLWarning: Output port is read internally: I2C_SCLK
> ** ToVHDLWarning: Output port is read internally: I2C_SDAT
> ** ToVHDLWarning: Signal is driven but not read:
> drive_spi_inst_read_Adr_inst_r_data2
> ** ToVHDLWarning: Signal is driven but not read:
> drive_spi_inst_read_Adr_inst_io
> ** ToVHDLWarning: Signal is not driven:
> drive_spi_inst_read_Adr_inst_w_data1
> ** ToVHDLWarning: Signal is not driven:
> drive_spi_inst_read_Adr_inst_w_adr_2
> ** ToVHDLWarning: Signal is not driven:
> drive_spi_inst_read_Adr_inst_w_adr_1
>
> Some of them are benign, some of them are to avoid.
> Not that I am converting your code as you posted yesterday.
> 1. ** ToVHDLWarning: Output port is read internally: G_SENSOR_CS_N
> This is (very probably) not your intention, and will (in VHDL) produce
> an *inout* port in stead of an *out* port. You can correct that by using
> local signals and assign the output port in a separate combinatorial
> procress.
>
> 2.** ToVHDLWarning: Port is not used: G_SENSOR_INT
> You actually are not using it.
>
> 3.** ToVHDLWarning: Output port is read internally: I2C_SCLK
> This is like 1.
>
> 4.** ToVHDLWarning: Output port is read internally: I2C_SDAT
> For a top-level module this can't be easily avoided. Note that in a VHDL
> top-file we would use a primitive like this:
> 	-- drive SDa via an open drain primitive
> 	od1 : opndrn port map(qs_SdaOut, IfSDa);
> which would be warning-free
>
> 5.** ToVHDLWarning: Signal is driven but not read:
> drive_spi_inst_read_Adr_inst_r_data2
>
> 6.** ToVHDLWarning: Signal is not driven:
> drive_spi_inst_read_Adr_inst_w_data1
> ** ToVHDLWarning: Signal is not driven:
> drive_spi_inst_read_Adr_inst_w_adr_2
> ** ToVHDLWarning: Signal is not driven:
> drive_spi_inst_read_Adr_inst_w_adr_1
> I'm not sure whether these three warnings should be there at all. You
> are using a Signal(intbv() as a constant. The generated VHDL is correct.
> The warning is correct though in stating that the Signal is not driven,
> read: depending on an input port.
>
> Perhaps I shouldn't have mentioned my preference of splitting opendrain
> and tristate signals into inputs, outputs and for the tristate enable.
> Now for your gw.py file this is no solution either as I understood that
> you are using the converted result as the top-file in your Quartus II
> project.
>
>
> Regards,
>
> Josy
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