+ Reply to Thread
Results 1 to 4 of 4
  1. #1
    Join Date
    Oct 2008
    Location
    Arizona or Minnesota
    Posts
    22

    Default Fastest baud rate w/PBP?

    So I suddenly need to go faster than 38,400 with a PIC16F883 and a 20 MHz xtal. I'm sending out on 4 pins, with no MAX232 chips involved. The good book says a max of 38,400, but haven't I seen postings that say (up to)115,300???.. Do I need to write a routine in assembler to do this?
    Thanks for listening,
    JR

  2. #2
    Join Date
    Oct 2005
    Location
    Sweden
    Posts
    3,271

    Default Re: Fastest baud rate w/PBP?

    If you're using SEROUT(2) then I think the answer is no. There's a formula that tells you how to specify the baudrate bits and for 115200 the result of that formula comes out negative = no go. I'm not sure but it's possible that DEBUG can work with higher baudrates, it might be worth a shot.

    With that said, that chip you're using has an USART, can't you use that?

    /Henrik.

  3. #3
    Join Date
    Oct 2008
    Location
    Arizona or Minnesota
    Posts
    22

    Default Re: Fastest baud rate w/PBP?

    Thanks for the reply. Yes the PIC has a USART, but I need to send serial data out a total of 4 pins... If you use Mister E's Multicalc, 115200 does give me a number. I have a more precise xtal coming. Right now my frequency counter says 19.84 MHz which would really screw up the baud rate. Granted, my 10:1 scope probe could be pulling the frequency that I read.
    I'll report back, once I get the new xtals.
    JR

  4. #4

    Default Re: Fastest baud rate w/PBP?

    If you use Mister E's Multicalc, 115200 does give me a number
    What number does it give?
    If you look at the table of numbers for SEROUT2, it pretty much maxes out at 38400.

    I have a more precise xtal coming. Right now my frequency counter says 19.84 MHz
    You're loading it with the scope probe. Better to measure it a different way.

    Even so, while that's not a great number for an xtal it's less than 1% error so the serial baud rate would probably be fine (if that table produces accurate numbers to begin with). I don't think a better xtal is going to do much for you.

    Since you're interested in the serial out data, perhaps just transmit a 'U' character ($55) and look at the individual bit times.

Similar Threads

  1. MCLoader baud rate
    By Charles Linquis in forum mel PIC BASIC Pro
    Replies: 9
    Last Post: - 14th July 2010, 01:41
  2. Rf module baud rate
    By tazntex in forum Serial
    Replies: 4
    Last Post: - 5th August 2008, 18:47
  3. Baud Rate Converter
    By paul.mcallister in forum Serial
    Replies: 3
    Last Post: - 14th June 2008, 23:26
  4. Baud rate calculation
    By Demon in forum Serial
    Replies: 12
    Last Post: - 21st July 2006, 22:02
  5. Detect baud rate
    By Dick M in forum mel PIC BASIC Pro
    Replies: 1
    Last Post: - 2nd July 2005, 21:10

Members who have read this thread : 0

You do not have permission to view the list of names.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts