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I am studying protocols and came across a concept of MS bit first(in I2C) and LS bit first(in UART). I couldnot understand the advantage/limitations one has over the other? on what basis is it decided that we shall have msb first or lsb first for the device we are designing?

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    \$\begingroup\$ A very minor advantage to MSBit first: it is easier to decode on a scope. \$\endgroup\$ – Mattman944 Jul 11 at 12:54
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There is no advantage one way or the other — it's just an arbitrary choice. But both sender and receiver must agree, or it won't work.

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  • \$\begingroup\$ yes, might be an arbitrary choice, but i've come across some applications like PRBS(pseudo random binary sequence) in which we need to take the o/p from MSbit side only(and will not get the same result from LSbit). . .maybe it is dependent on the application \$\endgroup\$ – Gayatri Jul 16 at 4:35
  • \$\begingroup\$ @Gayatri: That has nothing to do with this question, which is about serial communications. \$\endgroup\$ – Dave Tweed Jul 16 at 11:02
  • \$\begingroup\$ what i meant was it can be used in such an application, if i want to access my slave (which generates PRBS noise &uses MSBit 1st ) then i need to have a master that can Rx MSBit first. \$\endgroup\$ – Gayatri Jul 17 at 7:02
  • \$\begingroup\$ Your comment still does not make any sense. If you have a random bit generator, there is no "MSB" or "LSB" about it -- all bits have equal weight. How you choose to transmit those bits as bytes in a serial interface is still completely arbitrary. \$\endgroup\$ – Dave Tweed Jul 17 at 11:04
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Holy wars have been fought over this. Some people think stacking eggs big end down is best, while others insist that little end down is superior. Neither side has really been able to claim victory.

As a neutral user, you just need to know which one is expected by what and potentially convert between them a bunch.

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No advantages except consistent with documentation of IC’s such as SiPo PiSo for b0 to b7 and receiving end.

LSB vs. lsb = Byte vs bit

Don’tcha hate it when labels are b1 to b8 instead of b0 to b7? Or visa versa.

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