Setting I2C clock speed for something other than 100K/400K

Tim Simerly

Other Parts Discussed in Thread: CC3200

Dear Support:

I am using TI-RTOS and setting up the I2C with a I2C_Params_init call and the only options are 100K and 400K. If my customer wants to move to a slower clock rate like 50K, how would he do this? Please advise.

Thanks,
Tim

over 9 years ago

0 Benjamin Moore over 9 years ago

TI__Mastermind 30800 points

Hi Tim,

100Kbps and 400Kbps are the only transmission speeds supported on the CC3200. This is noted in section 7.1 of the Technical Reference Manual.

Best Regards,

Ben

0 Tim Simerly over 9 years ago in reply to Benjamin Moore

TI__Genius 9975 points

Hey Ben:

Yes, I understand that. But I am wanting to know if there is a way around that. There is a I2C driver call, I2CMasterInitExpClk(...). Is there a way of using this call to get the I2C module to run with a different clock that 100K/400K? Or is there an internal register I can write to that would allow me to change the I2C clock speed? Needing to know if this limitation of 100K/400K is a software issue (that can be changed) or a hardware issue (that prevents me from running with something other than 100K or 400K). Please advise.

Thanks,
Tim

0 Hnz over 9 years ago in reply to Benjamin Moore

Guru 39650 points

Hi,

Using direct writing into I2C peripheral registers can be set different clock than standard 100 and 400kbps. Peripheral driver supports only 100 and 400 kbps. For example I use 1 Mbps I2C in CC3200 with eeprom from ST. But 50K is also not a problem.

Jan

0 Tim Simerly over 9 years ago in reply to Hnz

TI__Genius 9975 points

Hey Jan:

Ok, thanks. I was hoping there was a way to do that from using the driver API. But given that I must do this via direct register access, I'm ok with that. Just needing to know if that was the path to take.

Thanks,
Tim

0 Benjamin Moore over 9 years ago in reply to Tim Simerly

TI__Mastermind 30800 points

Hi Tim,

Testing has been performed for the two standard speeds that are indicated in the Technical Reference manual. It is possible to set the TPR register for a different speed (and 50Kbps would be achievable), however, you will have to verify the performance.

Best Regards,
Ben

0 Tim Simerly over 9 years ago in reply to Benjamin Moore

TI__Genius 9975 points

Ok, understand and thanks Ben.

0 Tim Simerly over 9 years ago in reply to Tim Simerly

TI__Genius 9975 points

For those of you following this post, see below for the actual call that changes the I2C clock rate to 50 KHz:

// *****************************************************************************
// Change the I2C clock speed to 50 KHz
// *****************************************************************************
HWREG(0x4002000C) = 79;

and yes I confirmed that it works!

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Setting I2C clock speed for something other than 100K/400K