MPC5200 (Board: PM520) I2C Problem

MPC5200 (Board: PM520) I2C Problem

[RPo]

Hi,

I'm currently using the MPC5200 based board "PM520" and 
want to access the I2C bus. To do so, I attached a PCF8574P
to the bus. But I was not successful in setting the outputs
of this IC. 

Here is the code with which I tried to access the bus:
8<==================================================
  int i2c = 0, i = 0xfffffff;
  i2c = open("/dev/i2c-0",O_RDWR);
  if(i2c > 0)
    RT_TRACE(printf("I2C opened successfully.\n"));
  else
    RT_TRACE(printf("Error: I2C could not be opened.\n"));
  ioctl(i2c, I2C_SLAVE, 0x46);
  write(i2c, &i, 1);
8<==================================================

The open() and ioctl() calls are successful (checked with 
strace) but the write() call always returns -1 and an 
EREMOTEIO error. The device nodes have been created this way:

8<==================================================
mknod /dev/i2c-0 c 89 0
mknod /dev/i2c-1 c 89 1
chmod 666 /dev/i2c-*
8<==================================================

So here is my configuration:

Linux 2.4.25 (ELDK 3.1.1-2005-06-07)

The I2C modules were compiled after I had made some changes
to the i2c-pm520.c file in the kernel-tree:

8<================== ORIGINAL ======================
/* #define MPC5xxx_I2C1_ENABLE  0 */    /* Disabled     */
8<================== ORIGINAL ======================

8<================== MODIFIED ======================
#define MPC5xxx_I2C1_ENABLE     1       /* Enabled      */
8<================== MODIFIED ======================

I was unsure about the bus my code uses and so I decided to
enable both busses. These are the printks I get, when I load 
the modules:

8<==================================================
# /ftp/sbin/insmod ./i2c-core.o
i2c-core.o: i2c core module version 2.6.1 (20010830)
# /ftp/sbin/insmod ./i2c-proc.o
i2c-proc.o version 2.6.1 (20010830)
# /ftp/sbin/insmod ./i2c-dev.o
i2c-dev.o: i2c /dev entries driver module version 2.6.1 (20010830)
# /ftp/sbin/insmod ./i2c-algo-mpc5xxx.o speed=85
# /ftp/sbin/insmod ./i2c-pm520.o
i2c-algo-5xxx.o: scanning bus PM520 I2C module #1 interface...
............................................................................
....
................................................
i2c-pm520.o: I2C module #1 installed
i2c-algo-5xxx.o: scanning bus PM520 I2C module #2 interface...
............................................................................
....
.(0x51)......(0x58)(0x59)(0x5a)(0x5b)(0x5c)(0x5d)(0x5e)(0x5f)...............
....
............(0x7f)
i2c-pm520.o: I2C module #2 installed
8<==================================================

So, what are these identifiers on I2C module #2 interface? 
I can neither find them in the documentation of the EEPROM
nor the one of the realtime clock. write() calls to these
IDs are succesful, but it seems like nothing happens. The
same is for the other bus (module #1 interface).

Has anyone an idea or experience with I2C bus on the MPC5200?
Best regards and thanks for reading,
Rainer

Re: MPC5200 (Board: PM520) I2C Problem

[Andrey Volkov]

Hello Rainer
RPo wrote:
> Hi,
> 
> I'm currently using the MPC5200 based board "PM520" and 
> want to access the I2C bus. To do so, I attached a PCF8574P
> to the bus. But I was not successful in setting the outputs
> of this IC. 
<...snip..>

Revision of MPC5200? (third string engraved on the MPC)
If L25R then check this doco:
   http://www.freescale.com/files/32bit/doc/errata/MPC5200E.pdf
(if be short - I2C didn't work on this revision chips)

--
Regards
Andrey Volkov

Re: MPC5200 (Board: PM520) I2C Problem

[Roman Fietze]

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Hello,

On Friday 27 October 2006 09:29, Andrey Volkov wrote:

> Revision of MPC5200? (third string engraved on the MPC)
> If L25R then check this doco:
>    http://www.freescale.com/files/32bit/doc/errata/MPC5200E.pdf
> (if be short - I2C didn't work on this revision chips)

We have an "MPC5200CBV400 L25R Rev 2" on our boards, and we
successfully drive a PCF8563 real time clock and an UDA1380 Codec on
the same line.

The problems described in the errata are an arbitration loss problem
and, depending on teh chp's Rev, a clock noise problem.

Probably your problem is related to the connected I2C client?


Roman

-- 
Roman Fietze              Telemotive AG Büro Mühlhausen
Breitwiesen                            73347 Mühlhausen
Tel.: +49(0)7335/18493-45      http://www.telemotive.de


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Re: MPC5200 (Board: PM520) I2C Problem

[Andrey Volkov]

Hi,

Roman Fietze wrote:
> Hello,
> 
> On Friday 27 October 2006 09:29, Andrey Volkov wrote:
> 
>> Revision of MPC5200? (third string engraved on the MPC)
>> If L25R then check this doco:
>>    http://www.freescale.com/files/32bit/doc/errata/MPC5200E.pdf
>> (if be short - I2C didn't work on this revision chips)
> 
> We have an "MPC5200CBV400 L25R Rev 2" on our boards, and we
> successfully drive a PCF8563 real time clock and an UDA1380 Codec on
> the same line.
> 
> The problems described in the errata are an arbitration loss problem
> and, depending on teh chp's Rev, a clock noise problem.
> 
> Probably your problem is related to the connected I2C client?
Problem was not in noise. Chips of this rev. _sometime_ didn't
generate clock in ACK/NAK phase. Such behavior acceptable for
a RTC (you could reread clock, after timeout), but for eeprom - not.

--
Regards
Andrey