[ts-7000] Re: I2C interface on TS-7500

[Jonatan Olofsson <>]

It might be worth trying the onboard i2c first, since it works with a subset of devices (i.e. those _not_ using clock-stretching), and yours might just be one of them. I uploaded the partially working library i used when I was working on this, in case it could be of any help

Best regards,

Jonatan Olofsson

On Mon, Mar 7, 2011 at 10:22, limzhiyoong <> wrote:

Thanks for the discussion. Hmm I have just got started on the I2C for TS7500/752. So the safest bet is to use bit banging or reconfiguration of the fpga?

--- In Jonatan Olofsson <> wrote:
>
> Mostly for future reference,
>
> After a considerable amount of research and grey hairs, I finally found the
> issue with the I2C on the TS-7500: there is none.
> Or rather, it's broken, and apparently admittedly so. I got myself a logic
> analyzer to analyze the signals, and discovered that the Cavium processor
> does in fact send illegal bus commands when the receiver demands clock
> stretching (keywords: cavium i2c broken).
>
> After a month or so of mail conversations, it appears that this is a known
> issue at Cavium networks, but that the processor is too old to care about.
> So no luck there. TS, being very supportive as opposed to Cavium, suggested
> modifying the opencore SPI interface for I2C. While I may not get around to
> it myself, I noticed that there actually is some opencore code on this
> already at http://opencores.org/project,i2c
>
> <http://opencores.org/project,i2c>So if you're trying to get I2C working on
> the TS-7500 and require that clock-stretching is supported, I unfortunately
> must tell you that you cannot use the ordinary processor interface; you have
> to either use the FPGA or an external device (which I'm currently leaning
> towards, since I still need it in my case) for the I2C communication.
>
> Best regards,
> Jonatan Olofsson
>

> On Thu, Dec 23, 2010 at 19:24, Jim Jackson <> wrote:
>
> >
> >
> >
> >
> > On Thu, 23 Dec 2010, Jonatan Olofsson wrote:
> >
> > > It seems very few people has ever used the I2C on the TS-7500, so the
> > > documentation is very sparse. I'm determined to write a better one to
> > > publish once I've successfully figured it out, but as of now, i would
> > need a
> > > pointer or two.
> > >
> > > What I'm trying to accomplish is reading data from a Wii controller to
> > the
> > > TS. I know the controller works, but all I can seem to get out of it is a
> > > series of ones (0xFFFFFFFF), wherever i read from or write to. At first i
> > > thought the initialization was wrong, but after triple-checking
> > everything,
> > > in that case it must be because i misunderstand the way it sends data.
> > >
> > > From what I gather, the data in the TWI_WR_DAT register is sent LSB
> > first.
> > > Thus, to send the sequence "start - 0xA6 - 0xFE - 0x05 - stop", I should
> > > write 0x53 to the slave address register (=0xA6 in transferred bytes),
> > then
> > > 0x05FE to the write data register, and lastly enable the bit to start the
> > > transmission.
> >
> > Can't help with the ts7500 and hardware i2c, sorry. But I did get i2c
> > running on a ts7260, using the linux 2.4 i2c infrastructure with
> > a kernel bit banging module driving a couple of pins on the dio1 interface.
> >
> > A snip from a previous post here I made...
> >
> > This kernel module works with the standard kernel i2c framework so
> > supporting a standard interface to user programs.
> >
> > I used the stuff from this webpage...
> >
> >
> > http://tisnix.dommel.be/ts-7260/
> >
> > I then wrote a program to use the kernel interface to the i2c device to
> > get data.
> >
> > All this was done with the standard kernel Linux2.4.26-ts11 supplied by
> > Technologics with the ts7260 board. I had to compile all the standard i2c
> > modules as well as they are not supplied with the their kernel.
> >
> >
> > > So my first question is, am I getting these basic things right? It would
> > be
> > > really nice to hear from someone who successfully implemented something
> > more
> > > than that i2ctemp example, which really isn't very helpful..
> > >
> > > Best regards and Happy Holidays!
> > > Jonatan Olofsson
> > >
> > > On Thu, Dec 16, 2010 at 21:13, jonatan_olofsson

> > > < <jonatan.olofsson%40gmail.com>>wrote:

> > >
> > > >
> > > >
> > > > I'm still trying to figure out a few things about I2C communication..
> > Long
> > > > story short, i can't get it to work.
> > > >
> > > > First off, does anyone know what actually happens when data is
> > read/sent
> > > > through the registers? What acks/nacks are sent?
> > > > From what i gathered from taking my TS-7500 to a logic analyzer today
> > in
> > > > school, it sends start/stop conditions (and it appears to send data..)
> > > >
> > > > Part of why i'm asking is, when receiving or sending data, i read/write
> > > > from/to 32 byte registers. The device i need to interface sends data a
> > 6
> > > > byte format, so i would need to be able to read that, and i'm not quite
> > sure
> > > > what happens if the TS sends stop conditions after just four bytes..
> > > >
> > > > I really can't find any documentation on this.. I have the cavium
> > datasheet
> > > > with some register addresses, but still this says nothing of what
> > actually
> > > > happens on the bus, or how i can actually use the I2C interface..
> > > >
> > > > I would be tremendously grateful for hints on this, or documentation.
> > Or
> > > > code, for that matter.
> > > >
> > > > Best regards,
> > > > Jonatan Olofsson
> > > >
> > > >

> > > > --- In <ts-7000%40yahoogroups.com> <ts-7000%

> > 40yahoogroups.com>, "Kris"
> >
> > > > <kristechnologic@> wrote:
> > > > >
> > > > > The i2ctemp.c example on our FTP site (
> > > > ftp://ftp.embeddedarm.com/ts-arm-sbc/ts-7500-linux/samples/i2ctemp.c)
> > will
> > > > not work on the TS-7500 as the temp sensor on the TS-752 is SPI. It is
> > > > however a generic example of using the I2C hardware in the Cavium CPU.
> > We
> > > > attempted to use the Linux kernel interface to I2C however it will not
> > even
> > > > communicate correctly with our I2C temp sensor.
> > > > >
> > > > > This sample code is going to be the most efficient way of interfacing
> > > > with I2C unless you want to bit-bang the data out of DIOs which will be
> > much
> > > > slower since you have to go through the SBUS to access the DIO pins.
> > > > >
> > > > > -Kris Bahnsen
> > > > > Technologic Systems
> > > > >
> > > > >

> > > > > --- In <ts-7000%40yahoogroups.com> <ts-7000%

> > 40yahoogroups.com>,
> >
> > > > "jonatan_olofsson" <jonatan.olofsson@> wrote:
> > > > > >
> > > > > > Hi,
> > > > > >
> > > > > > First of all, thanks for the interesting discussions going on on
> > this
> > > > forum.
> > > > > >
> > > > > > I'm trying to get the I2C interface working on my TS-7500. There is
> > a
> > > > simple example available on the TS ftp, which unfortunately seems a bit
> > > > (way) too simple. So my question is, is there anyone who has written
> > code
> > > > for using the TWI interface, or do i have to write my own
> > implementation?
> > > > > >
> > > > > > Anyone got I2C working already who can give any pointers or hints?
> > > > > >
> > > > > > Best regards,
> > > > > > Jonatan Olofsson
> > > > > >
> > > > >
> > > >
> > > >
> > > >
> > >
> >
> >
> >
>

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