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[Discuss-gnuradio] I2C Addresses

From: Alan Gray
Subject: [Discuss-gnuradio] I2C Addresses
Date: Sun, 07 Sep 2003 17:59:27 +1000

Hi all,

I've just finished designing and building the hardware for my RF front end using the 4702 tuner and I'm looking to test it out. The structure of the control data for the 4702 is quite different to the 4937 though, so I have to go through and code a new interface for that side of things. Naturally I'm basing this off the code in microtune_4937.cc, I believe I've got the generation of the control bytes down, however I'm stumped about some addressing issues, even though the address should be the same as when using the 4937 according to data sheets.

In microtune_4937.cc the address listed for the tuner is 0x61 = 0110 0001
From the data sheets and the connections made (ie pin 11 to ground) I get an address of 0xC0 = 1100 0000

As neither of these addresses worked correctly for me, I decided to test communications with the MAX518 chip (as they are both connected to the same bus I figured that would rule out any errors in transmission) and was able to change the output voltage of the chip using the code in microtune_eval_board.cc. Looking at the addresses used for the MAX518 chip, the address in the program is 0x2C = 0010 1100, while that I calculate is 0x58 = 0101 1000.

From the MAX addresses, it looks like the address in the program is the address I determined right circular shifted one position
0101 1000 ->right shift
0010 1100

However, while similar, the same does not hold for the 4937's address

1100 0000 ->right shift
0110 0000
which is 0x60 not 0x61

As such, I'm a little confused as to what address I should use, and how in fact these should be generated. Any assistance anyone can provide would be most appreciated as I believe if I can figure this out everything should be go.


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