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Re: [Discuss-gnuradio] FrontEnd4702 take 2

From: John Gilmore
Subject: Re: [Discuss-gnuradio] FrontEnd4702 take 2
Date: Tue, 24 Feb 2004 23:36:35 -0800

> >     There are now two 4702 tuners on the board. The first one has its MA0
> > pin grounded so it should respond to I2C address 0xC0 and the second has its
> > MA0 pin left open so it should respond to I2C address 0xC2.
> While we're at it, let's really go all out -- the 4702 can handle 4 different
> addresses.  Thus, we could put 2 of these boards, with 2 4702s each, on the
> USRP at once, necessitating the 4 addresses.  With a pair of 2-pin jumpers we
> can accomodate that.  If you give the address select pin on one 4702 a 15K R 
> to

I thought these daughterboards are physically addressable.  If that
doesn't work for I2C, are there pins left in the interface connector
that can be wired on the motherboard to +5 or GND to encode the slot
number?  Wiring these pins to the 4702 address pins (and any other
chip-selects on the board) would automatically give different
addresses to as many boards as you plug in.

Doing something like this, to allow many copies of a board to be
plugged in at once without trouble, is a good idea for any board.  It
makes the system simple for software, simple for users, and simple for
hardware builders.


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