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Endianness of the I2C address jumpers? Product ID 4991 Rotar
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Endianness of the I2C address jumpers? Product ID 4991 Rotar

by loneboat on Fri Jun 11, 2021 12:56 pm

I'm looking to daisy-chain serveral of these together. I see that there are A0-A2 jumpers I can bridge to change the address from 0x36 to 0x3D, but the only documentation on it I can find says:

A0/A1/A2 - Using the three onboard address jumpers, you can connect up to 8 of these rotary encoders on a single I2C port. The first one will be at address 0x36, the last one at 0x3D when all three jumpers are soldered closed.


... which says nothing about the ordering of the bits. Is A0 the least-significant bit? Or is A2?

In other words:

Code: Select all | TOGGLE FULL SIZE
                Which is correct?           
                                           
            THIS:           or THIS:       
                                           
Address     A0  A1  A2      A0  A1  A2     
0x36        0   0   0       0   0   0       
0x37        1   0   0       0   0   1       
0x38        0   1   0       0   1   0       
0x39        1   1   0       0   1   1       
0x3A        0   0   1       1   0   0       
0x3B        1   0   1       1   0   1       
0x3C        0   1   1       1   1   0       
0x3D        1   1   1       1   1   1       


Also is this documented somewhere and I'm just not finding it?

Thanks

loneboat
 
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Joined: Fri Jun 11, 2021 12:38 pm

Re: Endianness of the I2C address jumpers? Product ID 4991 R

by adafruit_support_bill on Fri Jun 11, 2021 1:13 pm

A0 is the lsb of the address.

adafruit_support_bill
 
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Joined: Sat Feb 07, 2009 10:11 am

Re: Endianness of the I2C address jumpers? Product ID 4991 R

by loneboat on Fri Jun 11, 2021 1:13 pm

Thanks!

loneboat
 
Posts: 4
Joined: Fri Jun 11, 2021 12:38 pm

Please be positive and constructive with your questions and comments.