Lpc2000

You can use a MAX232 of Texas Instruments (easy to find), because the Vih of this is 2V (min), then you can connect 3V3 pin of uC directly (as TX), in another direction (RX), you can use a simple voltage divider, with resistors to do the 3V3 signal to uC. The disadvantage of MAX232 is capacitors are bigger than in a MAX3232 device (100nF typical). The most important parameter is Vih (min) than be smaller than I/O port voltage.  

Leo
  ----- Original Message ----- 
  From: Leon Heller 
  To: lpc2000@yahoogroups.com 
  Sent: Sunday, June 19, 2005 2:16 PM
  Subject: Re: [lpc2000] MAX232 and P1.20/P1.26 pins.


  ----- Original Message ----- 
  From: "Robert Adsett" <subscriptions@...>
  To: <lpc2000@yahoogroups.com>
  Sent: Sunday, June 19, 2005 6:01 PM
  Subject: Re: [lpc2000] MAX232 and P1.20/P1.26 pins.


  > At 01:31 AM 6/19/05 -0300, Boris Estudiez wrote:
  >> From LPC21xx Philips datasheet:
  >>
  >>"P1.20: LOW in this pin while /RESET is LOW, enables pins P1.25:16
  >>to operate as Trace port after reset."
  >>"P1.26: LOW in this pin while /RESET is LOW, enables pins P1.31:26
  >>to operate as Debug port after reset."
  >>
  >>I don't want to use Trace and Debug port.
  >>Should I connect P1.20 and P1.26 pins to +3.3V (via pull-up resistors) ?.
  >
  > Yes.
  >
  >>It's necessary ?
  >
  > I think so.  At the very least it's good defensive practice and gives you
  > pads to connect to if you want to probe  or add to the area.
  >
  > Speaking of datasheets.  Is anyone else having trouble getting them from
  > Philips site?  I keep getting "the page you requested is not
  > available".  This is the link I end up following
  >
  > http://www.semiconductors.philips.com/acrobat_download/datasheets/LPC2104_2105_2106-05.pdf
  >
  > Of course Philips site is probably one of the slowest on the web, I
  > actually timed the 2104 product page and it took 1/2 a minute to render,
  > and that discourages a lot of exploration.
  >
  > Hmm, I just checked with IE.  It seems to be specific to firefox.  Render
  > speed is about the same for both, turning javascript off (I usually do but
  > for some reason it was on) helps a lot.  I'll try a few other systems to
  > see if I can nail down what is happening with the pdf download.

  I just accessed the LPC2106 page with IE and it took under 2s! I have a 4 Mb 
  broadband connection (soon to be updated to 8 Mb) which helps.

  Leon 


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