[Discuss-gnuradio] I2C Addresses

[Alan Gray]

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.

Alan