Re: [Discuss-gnuradio] Multiple I2C devices on Rx daughtercards

[Eric Blossom]

On Mon, Jan 11, 2010 at 10:51:09AM -0600, John Orlando wrote:
> Hi Matt,
> In reviewing the schematic of the dbsrx daughtercard, I noticed that there
> are two i2c devices (the EEPROM and the MAX211x receiver chip).  In general
> for the daughtercards, address bit A1 determines side A or side B, and A0
> determines if the card is an rx or tx card, and this is hard-coded by the
> USRP itself.  So...if a user has two dbsrx cards in their USRP, I think the
> EEPROM of the dbsrx on side A would have the same address as the MAX211x on
> side B, and vice versa.  Wouldn't this be an issue?

> Also, is there a reason that address bit A2 isn't used to select different
> i2c devices on the same card?

I2C devices have a 7-bit address.  Some of them are fixed depending on
the device.  E.g., on the 24LC024, the top 4-bits are 1010, which is
different from the bits hardwired into a low speed A/D, D/A, etc.
Take a look at the datasheets.

Eric