5 Replies Latest reply on Mar 13, 2019 4:07 AM by SampathS_11

    Question on Cypress AN2358  - Manchester decoder - implementation

    DeRy_2459691

      Hello all,

      I have question(s) on some details in the AN2358, the Manchester Decoder implementation with PSoC1 ( I don't think the example from the AN limited to the PSoC1, surely can do on other PSoC families; but this is un-related to question I want to ask; however the AN is old, so I post my question under PSoC 1 thread).

       

      On P3, where it discusses the clocking to the CNTR8, VC3 clock signal / counter clock frequency: since we timing 3T/4 of bit period, it must be at least 4 times the bit rate.

      But what I don't understand is the discussion about oversampling on this particular case.  We only "take" a single sample, when the counter triggers the timeout of the 3/4 of the period. I don't think I understand or see oversampling here. Way I understand it, whichever frequency we chose,  we still will trigger once on the 3/4ths of that period, no matter the number of ticks.

      So what's the point at all increasing the frequency beyond 4x bit rate ... ?

       

      I've seen other decoder implementations (in software) which do take multiple samples say at x16 rate, but they apply filtering on the samples.  None if which I see or understand happening in this AN.

       

      If someone could clarify that for me I would greatly appreciate it.