Is this schematic right for a HC-05 to PIC?

Discussion in 'The Projects Forum' started by Gareth Morgan, Jan 12, 2015.

  1. Gareth Morgan

    Thread Starter New Member

    Oct 26, 2014
    7
    0
    Hi,
    I'm new to all this and I've designed a schematic for a POV clock. I thought I had the schematic correct when connecting the HC-05 bluetooth module to the PIC16f877a, but a quick search on google images shows different versions.

    Need some clarification from more experienced users!
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,441
    3,361
    Why do you need R21 and R22?
     
  3. Gareth Morgan

    Thread Starter New Member

    Oct 26, 2014
    7
    0
    Its voltage divider network, as the HC-05 can't have more than 3.3V going into it. The resister values are accuate though yet as I'm not 100% sure of the power going into the PCB yet.
     
  4. MrChips

    Moderator

    Oct 2, 2009
    12,441
    3,361
    41Ω load seems somewhat extreme. I would try something like R21 = 100Ω, R22 = 200Ω if you want to reduce 5V to 3.3V
     
  5. tshuck

    Well-Known Member

    Oct 18, 2012
    3,531
    675
    UART is typically Rx to Tx and Tx to Rx (the way you have it), but the signals are sometimes switched when getting stuff from China.

    I'd recommend testing the module first, or adding a series resistor to each of the lines in case of a signal swap.
     
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