Serial to prop converters
BradC
Posts: 2,601
So I've been waiting for the ram to arrive for my Mac, and it finally did. Now I need to put together some serial converters to try and track down an issue with RS232-Prop stuff. I notice Parallax has the 3 transistor schematic, the schematic for the Dracblade is available also. Went looking for the schematic for Bill's Serplug....
One oddity hit me with the Parallax design. Not only is the polarity of the DTR different to what you get on the Prop Plug, but unless the DTR is held at the right polarity after the reset, there is no voltage available to swing the RX line from the prop. Never spotted that before.
So, what circuits are people actually using?
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"I mean, if I went around sayin' I was an emperor just because some moistened bint had lobbed a scimitar at me they'd put me away!"
One oddity hit me with the Parallax design. Not only is the polarity of the DTR different to what you get on the Prop Plug, but unless the DTR is held at the right polarity after the reset, there is no voltage available to swing the RX line from the prop. Never spotted that before.
So, what circuits are people actually using?
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"I mean, if I went around sayin' I was an emperor just because some moistened bint had lobbed a scimitar at me they'd put me away!"
Comments
Basically, it is the Maxim app note circuit for Rx&Tx, and using the 2nd receiver for DTR, and the equivalent of the demo board DTR transistor circuit.
It works great [noparse]:)[/noparse]
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www.mikronauts.com E-mail: mikronauts _at_ gmail _dot_ com
My products: Morpheus / Mem+ / PropCade / FlexMem / VMCOG / Propteus / Proteus / SerPlug
and 6.250MHz Crystals to run Propellers at 100MHz & 5.0" OEM TFT VGA LCD modules
Las - Large model assembler Largos - upcoming nano operating system
cheers ... BBR
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cheers ... brian riley, n1bq, underhill center, vermont
The Shoppe at Wulfden
www.wulfden.org/TheShoppe/
www.wulfden.org/TheShoppe/prop/ - Propeller Products
www.wulfden.org/TheShoppe/k107/ - Serial LCD Display Gear
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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)·
· Prop OS: SphinxOS·, PropDos , PropCmd··· Search the Propeller forums·(uses advanced Google search)
My cruising website is: ·www.bluemagic.biz·· MultiBlade Props: www.cluso.bluemagic.biz
You have to connect the RX and TX line "the normal way" and DTR to the second, empty, input. The level-converted output of the DTR line is already inverted after the Max... You can go directly to Reset.
BST works fine with that circuit, but the Prop-Tool for Windows needs a 0.01µF cap in series between DTR and the Max....
If you use the 5V version (max232) you have to put a 220ohm...1k Resistor between the Prop-Reset-Line, Prop-RX and the Max232. If you use the Max3232 you don't need the resistors. It's already 3.3V
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some say the devil is dead... ...tish army!
True, but the cost of either one of those chips by itself exceeds the entire cost of my P1 including the PCB.
cheers ... BBR
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cheers ... brian riley, n1bq, underhill center, vermont
The Shoppe at Wulfden
www.wulfden.org/TheShoppe/
www.wulfden.org/TheShoppe/prop/ - Propeller Products
www.wulfden.org/TheShoppe/k107/ - Serial LCD Display Gear