About TWI Frequency

RE: About TWI Frequency

emyang333 — Fri, 28 Sep 2018 07:21:58 GMT

I am working with Yoseph Kim.

This issue is due to external pull up register not to be connected by I/O expander.

After enabling I/O expander, issues were fixed.

Yoseph Kim — Fri, 28 Sep 2018 00:23:15 GMT

Hello Jorgen Holmefjord!

Please reference to below.

1. Ofcourse. This device is support 400kHz. I checked the 400kHz support via device company.

2. If i changed TWI_FREQUENCY_FREQUENCY_K400 value from 0x06680000UL to 0x0CCA8940UL,

the frequency wave is succesfully 400kHz. But twi_read function is working on 0x06680000UL, not work on

0x0CCA8940UL.

3) driverIC(in below picture) mean peripheral device.

Jørgen Holmefjord — Thu, 27 Sep 2018 12:54:40 GMT

Which device are you interfacing? Does it support 400kHz rate?

Can you provide logic trace of the TWI bus for the device you are having issues with?

Yoseph Kim — Thu, 27 Sep 2018 07:33:00 GMT

Add comment...

Try additional test...

I am setting the TWI_FREQUENCY_FREQUENCY_K400 variable from 0x06680000UL to 0x0CCA8940UL.

In this case the working is well but, this value is corresponding to about 800kbps.

I don't understand this situation.

Yoseph Kim — Thu, 27 Sep 2018 00:59:13 GMT

Add comment...

In my case, "other board(ex. driver IC or other sensor)" is enough for 400kHz frequency.

And changed resister from 4.7KΩ to 2.2KΩ for testing this issue.