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.
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 <> 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, "Kris" <> 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, "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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