Basic stamp can do 50,000 baud better than 38,400

metron9 · 2007-11-16 02:05

I was working on my little tiny2313 PWM project using one of the majic crystal numbers 14.7456MHZ so i could use 38.4khz serial baud rate with the basic stamp. Having problems with it I looked into it further. I guess the serial baud rate is based on a 1MHZ clock on the BS2 and 9600 baud has a 0.2% error·percentage and 38.4K has an -18.6% error percentage. I switched to a 20Mhz crystal and put in 50kbs baud rate on the tiny2313 and set the BS2 baud rate to 0 as the formula (1,000,000/baud)-20 is zero. It runs great with no errors now.

Here is a video of 4 PWM LED's using the following BS2 code conected to the tiny2313 chip using serial output at 50kbs. Frequency is 39khz on the PWM.

·http://www.acousticlights.com/pwmtiny2313.html

' {$STAMP BS2}
' {$PBASIC 2.5}
' {$PORT COM1}
baud CON 0
i VAR  Byte
j VAR  Byte
k VAR  Byte
l VAR  Byte
reset:
i=0
j=0
k=0
l=0
HIGH 0
LOW 0
PAUSE 1
FOR i=1 TO 254
 SEROUT 0, baud, [noparse][[/noparse]i,j,k,l]
NEXT
GOTO start
main:
FOR i=1 TO 254
 l=l-1
 SEROUT 0, baud, [noparse][[/noparse]i,j,k,l]
NEXT
start:
FOR j=1 TO 254
 i=i-1
 SEROUT 0, baud, [noparse][[/noparse]i,j,k,l]
NEXT
FOR k=1 TO 254
 j=j-1
 SEROUT 0, baud, [noparse][[/noparse]i,j,k,l]
NEXT
FOR l=1 TO 254
 k=k-1
 SEROUT 0, baud, [noparse][[/noparse]i,j,k,l]
NEXT
FOR l=254 TO 1
 SEROUT 0, baud, [noparse][[/noparse]i,j,k,l]
NEXT
  FOR i=1 TO 255
    SEROUT 0,baud,[noparse][[/noparse]i,0,0,0]
  NEXT
  FOR i=255 TO 1
    SEROUT 0,baud,[noparse][[/noparse]i,0,0,0]
  NEXT

  FOR i=1 TO 255
    SEROUT 0,baud,[noparse][[/noparse]0,i,0,0]
  NEXT
  FOR i=255 TO 1
    SEROUT 0,baud,[noparse][[/noparse]0,i,0,0]
  NEXT

  FOR i=1 TO 255
    SEROUT 0,baud,[noparse][[/noparse]0,0,i,0]
  NEXT
  FOR i=255 TO 1
    SEROUT 0,baud,[noparse][[/noparse]0,0,i,0]
  NEXT
  FOR i=1 TO 255
    SEROUT 0,baud,[noparse][[/noparse]0,0,0,i]
  NEXT
  FOR i=255 TO 1
    SEROUT 0,baud,[noparse][[/noparse]0,0,0,i]
  NEXT
  FOR i=1 TO 255
    SEROUT 0,baud,[noparse][[/noparse]i,i,i,i]
  NEXT
  FOR i=255 TO 1
    SEROUT 0,baud,[noparse][[/noparse]i,i,i,i]
  NEXT
  FOR i=10 TO 250 STEP 10
   SEROUT 0,baud,[noparse][[/noparse]i,i,i,i]
   PAUSE 30
   SEROUT 0,baud,[noparse][[/noparse]0,0,0,0]
   PAUSE 30
  NEXT
  FOR i=250 TO 0 STEP 10
   SEROUT 0,baud,[noparse][[/noparse]i,i,i,i]
   PAUSE 30
   SEROUT 0,baud,[noparse][[/noparse]0,0,0,0]
   PAUSE 30
  NEXT
GOTO reset

·

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Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!

Bill Chennault · 2007-11-16 03:09

metron9--

Way cool!

Why are your videos so much better than mine?

--Bill

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You are what you write.

metron9 · 2007-11-16 05:54

I am using a Cannon OPTURA 50 Digital camcorder I think about $600 or $800 and Macromedia Flash Professional and Dreamweaver to make the flash streaming video file. I did not think your video was so bad.

The video like this one is made using a product called camtasia studio it also makes swf file format video for streaming web download.

http://www.acousticlights.com/vnq660.html

This is the output from a vnq660 quad high side mosfet that can output 6 amps per channel. The PWM Frequency is about 600hz because the turn on and turn off time of this quad fet is 70 and 140 uS max. However, this is a reason not to use this fet for a PWM application with high current because the fet would be operating in its in between on and off state and waste a lot of power (heat up). I originally was going to use this for an LED dimmer but I did not read the on off times. Makes a nice high side switch though.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!

Bill Chennault · 2007-11-16 13:28

metron9--

My setup is not TOO diffferent from yours, other than I am simply using the raw mpg output of the 5 megapixel Sony Mavica.

I have Dreamweaver Professional, but do not know how to really use it. To my knowledge, I do not have Macromedia Flash Professional.

I discovered that my REAL problem with my movie quality was that I had it set to play at full screen. DUH!

I like your PWM LED display!

Thanks for the advice.

--Bill

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
You are what you write.

Basic stamp can do 50,000 baud better than 38,400

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