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Posts: 3
Registered: ‎12-27-2016
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Writing a software driver for the Si5341B

Having issues with the Si5341B, can't get any clock output. Not sure if my software is loading the chip correctly, wanted to ask about that.

I am using an Si5341B clock chip on a custom FMC card. I created a CBPro project to match my board schematic, exported out the settings as a header file, and loaded the header file into the Si5341B via I2C.

The I2C address for this part is 0x77, and was set with a DIP switch for the A0/A1 pins. I'm able to successfully read back the 0x77 value from address 0x000B. However, certain other values I can't read back the way I wrote them at all. For instance, the contents of 0x0943 is always 0 even though I need it to be 1 since that corresponds to VDDA=3.3V...

Is there more I'm supposed to do other than write these 281 registers into the Si5341B? What's the magic that makes the part work?

Thanks for your help!

Posts: 3
Registered: ‎12-27-2016

Re: Writing a software driver for the Si5341B

Really struggling getting this chip to work... Hoping someone can help me out with it.

 

Just to confirm, I can definitely do r/w on some of the I2C registers of my Si5341. However, it seems that my settings don't get applied across the board - 0x943 does not change no matter what I do. Is this normal? Is there something else besides writing to the registers that needs to be done?

 

C'mon Silabs experts, help me out... Will send beer Man Tongue

Posts: 70
Registered: ‎03-03-2014

Re: Writing a software driver for the Si5341B

I hope the attached application note helps out

 

Sincerely

Fran

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Posts: 3
Registered: ‎12-27-2016

Re: Writing a software driver for the Si5341B

Hi Fran,

 

The mechanism described in the app note was exactly what I needed. Everything is working now. This perfectly explains why I was able to write to 0x000B - the page offset for that is the default 0x0, so that register was accessible on power-up. Thank you so much for your help with this.

 

Folks, I cannot overstate how important the information and especially the examples in this app note are for getting these devices to work! This is not well described in the datasheet or family reference guide at all. Not only should the app note be referenced in both docs, but the examples should certainly be in the family reference guide front and center.