Occasional Contributor
Super ContributorHi,
documentation clearly specifies to support 400 kHz maximal. To find out what's the actual limitation, you probably need to get familiar with the documentation and IP core details yourself.
In case of soft I2C IP, speed is fixed to 100 and 400 kHz, there's one bit to switch between both. Using a different speed would require to modify the IP source code.
Stratix 10 HPS has preset SCL high and low clock tic counts for standard and fast mode. I read the documentation so, that lower counts are possible (see 20.4.5.1. Minimum High and Low Counts). If I2C can actually operate with lower settings must be tested.
I2C operation speed is not only limited by controller timing but also by time constant (pull-up resistor and load capacitance) of open drain bus. Intel I2C IP doesn't support push-pull bus drivers for Hs mode.
Occasional ContributorHi,
Please understand my query,
I am not asking for I2C soft IP speed and its limitations. My query is not around I2C, my question is all about
open-drain IOs that come with stratix-10 device.
Please let me know - what is the max speed the open-drain IO can operate ?
Thanks,
Kiran
Occasional Contributorso, do you mean - that Stratix-10 open-drain IO is limited to operate upto max 400KHz, time-constant of open-drain IO does not support to run beyond 400Khz ? Please request for a binary answer.
Super ContributorYou did not refer to IO speed in initial posts, really confusing. Speed of open drain is surely not limited to 400 kHz, it can be affected by varying the pull-up resistors. 400 kHz for fast mode has been specified in I2C standard to support common applications. Details are discussed here https://www.nxp.com/docs/en/user-guide/UM10204.pdf
I suggest to check the achievable speed for your actual hardware, at least HPS I2C interface should allow to adjust speed.
