Topic: FMC160 CPLD I2C Max Speed  (Read 3038 times)

dmoto20 June 26, 2014, 02:03 AM

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Hi 4DSP,

This is a follow on to venka's thread with similar subject.  I too am having issues with the CPLD's I2C, but no problems with the EEPROM or ADT7411.  I'm running the bus at 400 kHz and using Linux's i2cget and i2cset tools on a custom Zynq FMC carrier. 

Can you please indicate whether the CPLD can support the standard I2C data rates of 100 kHz and 400 kHz?

Thanks,
Dave

dmoto20 June 26, 2014, 09:11 PM (#1)

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So I was able to read the correct value of the Version Register using 100 kHz, but not 400 kHz.
 
4DSP, can you please provide detailed information about how the CPLD's I2C interface works?  I have similar questions and issues as venka did and I'd rather not waste time with trial and error trying to reverse engineer the protocol and trying to determine whether a data rate of 100 kHz is still too fast and causing problems.
 
- does the control word act as a 32-bit left-shift register?
- which bytes to read/write for the various devices?
- little/big endian byte ordering?
- locations in which the data is returned
- are values written to write-only registers persistent or are they cleared? 
- etc.
 
Thanks.

arnaudNL June 27, 2014, 06:38 AM (#2)

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Dear Sir,


We don't have specific documentation but the CPLD model is part of the simulation environment (fmc160_cpld.vhd) and the reference firmware is configuring the chipset via the CPLD. I assume these two references should be sufficient.


The FMC160 user manual also has the CPLD register map and details about the status register in Appendix B.


Let me know if this is not the case.


Best Regards,
Arnaud

dmoto20 June 27, 2014, 02:51 PM (#3)

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Hi Arnaud,
 
Yes, the fmc160_cpld.vhd file sufficiently describes the CPLD I2C interface.  Thank you.
 
In my humble opinion, a complete CPLD I2C interface description should be included in the FMC160 user manual for customers that would like to use the FMC160 without having to install the 4FM SDK and knowing to dig through the 4DSP BSP and simulation environment files to get the required information.
 
Thanks,
Dave

arnaudNL June 30, 2014, 05:49 AM (#4)

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Dear Dave,


I am forwarding your comment to the right persons.


I am happy you could find the information you were looking for.


Best Regards,
Arnaud

arnaudNL June 30, 2014, 05:49 AM (#5)

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This topic is being closed because the issue is considered as resolved by 4DSP. Feel free to create a new topic for any further inquiries.