OPENCORES.ORG

Oh and you might want to change the lines

	SCL <= SCLo when (SCLo = '0') else 'Z';
	SDA <= SDAo when (SDAo = '0') else 'Z';

To

	SCL <= '0' when (SCLo = '0') else 'Z';
	SDA <= '0' when (SDAo = '0') else 'Z';

No great reason than I'd like it that way and I think compilers find it
easier to work with, they are assigning a level not an equality. Should in
the end be the same output, but I work on the preemies that the easier you
make it for the compilers the more likely you are to get what you want.
[rih] I do agree, however there are certain lesser brilliant engineers that
have no idea what to do with this. Therefore I provided the SCLo and SDAo
signals. Both are tied off to zero, so the end effect is the same.

Richard

Andrew Mulcock

-----Original Message-----
From: cores-bounces@o... [mailto:cores-bounces@o...] On
Behalf Of Fabien Marteau
Sent: 10 April 2008 08:50
To: Discussion list about free open source IP cores
Subject: Re: *** PROBABLY SPAM *** RE: [oc] i2c ocore linux driver.

Thanks for your quick response.

I used this VHDL file :
http://www.opencores.org/cvsweb.cgi/~checkout~/i2c/vhdl/Attic/wishbone_i2c_m
aster.vhd?rev=1.1;content-type=text%2Fplain

And I just changed this line :
ADR_I : in unsigned(1 downto 0); -- lower address bits
with
ADR_I : in std_logic_vector(1 downto 0);		-- lower address
bits

And I added some signals on process sensivity list:
ocess(clk, nReset, state, dcnt,
core_txd,core_cmd,go,start,read,core_ack,sr,ack_in,stop)
[...]
nxt_state_decoder : process (clk, nReset, state, cmd,txd,Din)
[...]
output_decoder: process (clk, nReset, state,SCLo,sSDA,Din)

To synthetize with less warning.

And I added these lines in my top component :

	SCL <= SCLo when (SCLo = '0') else 'Z';
	SDA <= SDAo when (SDAo = '0') else 'Z';
	SCLi <= SCL;
	SDAi <= SDA;

I've got some warning in synthesis with xst:

WARNING:Xst:646 - Signal <txd> is assigned but never used.
WARNING:Xst:646 - Signal <we_a3> is assigned but never used.

The first warning is strange, because in VHDL txd *is* assigned.

FabM

2008/4/9 Richard Herveille <richard@h...>:
>
>
>
>
> The core never releases SDA and SCL at the same time.
>
> The order you specified sounds fine and it works on the 8bit interface.
>
> Are you sure you didn't break anything when you modified the 8bit
interface to a 16bit interface?
>
>
>
> Richard
>
>
>
>
>
>
> From: cores-bounces@o... [mailto:cores-bounces@o...] On
Behalf Of Fabien Marteau
> Sent: 08 April 2008 11:41
> To: cores@o...
> Subject: [oc] i2c ocore linux driver.
>
>
>
> Hello,
>
> I integrated the i2c ocore IP(VHDL) in a design with other Wishbone IP and
a irq manager core.
>
> The FPGA (spartan3) is connected to an ARM-processor (imx) with linux as
operating system ( http://www.armadeus.com).
>
> With my design, I only can read/write in 16bits data bus mode (with
sel=11). Then I write on register TXR and CR at the same time for example.
Reading the VHDL
> IP code I found these address decode:
>
> ----------------------------------
> RXR       |  SR      | 11
> TXR       |  CR      |  10
>              |  CTR     | 01
> PRERhi | PRERlo | 00
> ----------------------------------
>
> To test this core, I branched an accelerometer on i2c bus (address 0x1d)
and I read/write on the same register (0x16). Then I wrote a simple proc
driver that do :
>
> #unmask interrupt for i2c in interrupt manager:
> write 0x0002 in IRQ_MASK
> #Configure i2c speed prescaler (100kHz, FPGA clock is 96MHz)
> write 0x00bf in PRESCALER (address 00)
> #Enable core and enable interruption
> write 0x00c0 in CTR (address 01)
> #send start and address in write mode (address 0x1d<<1) and acknowledge
interrupt
> write 0x3a91 in TXR_CR (address 10)
> ---- wait for interruption
> #send subaddress, ackowledge core interrupt an set WR
> write 0x1611 in TXR_CR (address 10)
> #acknowledge interruption on my irq_mngr
> write 0x0002 on IRQ_ACK
> ---- wait for interruption
> # write the value (0xbb) set stop bit wr bit and acknowledge interruption
> write 0xbb51 on TXR_CR (address 10)
> --- wait for interruption
> #set stop bit and acknowledge interruption
> write 0x0041 on TXR_CR (address 10)
> #acknowledge interruption on my irq_mngr
> write 0x0002 on IRQ_ACK
>
> That work well but, when I write for read at the same subaddress with :
>
> #send address 0x1d, set write bit set start bit and acknowledge interrupt
> write 0x3a91 in TXR_CR (address 10)
>
> And I look traces on scope I see no start condition. SDA and SCL are
switching to 0 at the same time. It's ok to read, the component return the
good value, but this can be a problem for some components.
>
> Is somebody has this problem, or do you think it is a wrong programming ?
>
> I saw there is a linux driver for this core but, of course, without
irq_mng and with 8bit write. I will try to modify it to read/write in
16bits.
>
> Thanks
>
> Fabien M
>
>
> _______________________________________________
> http://www.opencores.org/mailman/listinfo/cores
>
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