Pull up resistor on P28

James Long

I'm doing some design work, and have a question.

Will a pull up resistor on P28 cause a problem with the Propeller boot operation?

I figure not, but I want to make sure before the prototypes are made.

James L

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
James L
Partner/Designer
Lil Brother SMT Assembly Services

Are you addicted to technology or Micro-controllers..... then checkout the forums at Savage Circuits. Learn to build your own Gizmos!

Toby Seckshund

I always have pulled up 28,29,30 and 31, with 10K. Just seemed safer, never had any probems.

Blade2 has them too.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Style and grace : Nil point

James Long

Toby Seckshund said...
I always have pulled up 28,29,30 and 31, with 10K. Just seemed safer, never had any probems.

Blade2 has them too.

Thanks Toby. I figured that was the case. As I understand it, a pull up is not needed for boot, because the Propeller drives that line actively, but if a pull up is present, it doesn't matter.

James L

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
James L
Partner/Designer
Lil Brother SMT Assembly Services

Are you addicted to technology or Micro-controllers..... then checkout the forums at Savage Circuits. Learn to build your own Gizmos!

Cluso99

P28 should have a 10K pullup. It works without it because the prop drives this line when reading the eeprom. IIRC it is on some parallax boards.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Links to other interesting threads:

· Home of the MultiBladeProps: TriBlade,·RamBlade,·SixBlade, website
· Single Board Computer:·3 Propeller ICs·and a·TriBladeProp board (ZiCog Z80 Emulator)
· Prop Tools under Development or Completed (Index)
· Emulators: CPUs Z80 etc; Micros Altair etc;· Terminals·VT100 etc; (Index) ZiCog (Z80) , MoCog (6809)
· Search the Propeller forums·(uses advanced Google search)
My cruising website is: ·www.bluemagic.biz·· MultiBladeProp is: www.bluemagic.biz/cluso.htm

JackBak

On a related note is there documented anywhere (so far I haven't found it) an equivalent circuit for the Prop I/O pins? I am trying to track down parasitic oscillations and probably ringing when I interface with an external device that I must treat as a black box. I would like to see said circuit to understand when and were pull-ups, filter caps, clipping diodes etc. are needed.

Drone

JackBak,

I too would like to see an equivalent circuit for the propeller i/o pins, or more specifications at least. I would also like to see a recommended timing diagram for the programming sequence.

Rgds, David

JackBak

David,

Nice to know it's not just me, and at least two of us can't find the data -- yet need it.

Regards,
Jack