Making P30 high resets Propeller Demo board if USB is not connected ???

Bean

On my demo board, if I make pin 30 high it resets the propeller chip.
I have a program that transmits data to the PC, but I need to run it without a PC too.

Is there any way to prevent this rebooting ?

To see the problem, load the attached program into the EEPROM.
When you turn on the demo board when it is connected to a PC all the LEDs will stay on.
If you are NOT connected to the PC they will flash as the propeller keeps getting reset.

PUB Main
  dira[noparse][[/noparse]23..16] := 255
  outa[noparse][[/noparse]23..16] := 255
 
  dira[noparse][[/noparse]30] := 1
  outa[noparse][[/noparse]30]:=1
 
  repeat

Bean.
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Use BASIC on the Propeller with the speed of assembly language.

PropBASIC thread http://forums.parallax.com/showthread.php?p=867134

March 2010 Nuts and Volts article·http://www.parallax.com/Portals/0/Downloads/docs/cols/nv/prop/col/nvp5.pdf


Post Edited (Bean) : 3/10/2010 3:55:58 PM GMT

Oldbitcollector (Jeff)

@Bean

Thanks for bringing this up!

I saw this for the first time last night with one of my programs which uses the Parallax Serial Terminal object for debugging variables. I was starting to think I was going to have to do some bug hunting soon.

OBC

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Visit the: PROPELLERPOWERED SIG forum kindly hosted by Savage Circuits.

Bean

I'm assuming it's actually the FTDI chip that is causing the reset.
But I don't know ???

Bean

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- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Use BASIC on the Propeller with the speed of assembly language.

PropBASIC thread http://forums.parallax.com/showthread.php?p=867134

March 2010 Nuts and Volts article·http://www.parallax.com/Portals/0/Downloads/docs/cols/nv/prop/col/nvp5.pdf
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John Abshier

I can replicate the behavior.

John Abshier

Bean

I have found that if I wait until the RX pin (31) is high before I make pin 30 high, then my program will not reset.

So I guess the RX pin stays low until it is connected to USB. This makes sense since a serial BREAK is the line held in the not-active state (which would be low). And a cable not connected would be considered a BREAK.

Bean.

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- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Use BASIC on the Propeller with the speed of assembly language.

PropBASIC thread http://forums.parallax.com/showthread.php?p=867134

March 2010 Nuts and Volts article·http://www.parallax.com/Portals/0/Downloads/docs/cols/nv/prop/col/nvp5.pdf
·

Mike Green

Bean,
There's a sneak path for power through the FTDI chip when there's no PC connected and that causes resets as you describe. The transmit signal from the Propeller ends up partially powering the FTDI chip and there's enough power to produce a reset pulse. Solutions include:

1) Leave a PC connected

2) Don't transmit through the FTDI chip if there's no PC there (leave pin 30 in input mode)

3) Disconnect the reset line except when you're downloading to the Propeller

4) There was one other solution involving a stiff pullup on the FTDI chip, but I don't remember the details.

hover1

As to #4. This is only one of the threads that I could find at the moment. I know there are one or two others.

·http://forums.parallax.com/showthread.php?p=847290

Jim

Duane Degn

Wow! Thanks for bringing this up. I was going crazy yesterday trying to figure out why my Prop to Prop communication wouldn’t work without a USB cable attached to the Demo Board (I had debug statements sent to the computer).

Duane

Phil Pilgrim (PhiPi)

This information ought to be included in the documentation of every board that does not include a buffer between the FTDI chip and the Prop or pullup(s) on A30 and/or A31 -- at least until those board designs can be fixed.

-Phil