RS232 advice
Mike B.
Posts: 31
I too am a newbie to the Prop chip.··
··I am building a R/C submarine and WAS using the BS2P40 as the smarts for the project then I stumbled onto the Prop chip.
· Question is this.· Almost everything I need to do both in the sub and the control unit involves speaking RS232, both TTL level 232 and "real" Rs232.· Is there a Maxim chip (or anyother brand) that likes talking to the 3.3v levels on the prop chip?· Or should I simply use series resistors to limit the current into the Prop??
· If this seems like a dumb question it's because I am, well, Dumb...
Mike B.
··I am building a R/C submarine and WAS using the BS2P40 as the smarts for the project then I stumbled onto the Prop chip.· Question is this.· Almost everything I need to do both in the sub and the control unit involves speaking RS232, both TTL level 232 and "real" Rs232.· Is there a Maxim chip (or anyother brand) that likes talking to the 3.3v levels on the prop chip?· Or should I simply use series resistors to limit the current into the Prop??
· If this seems like a dumb question it's because I am, well, Dumb...
Mike B.
Comments
A·chip like a MAX 232 inverts the signal and increases the voltage and you get a·larger voltage going out. This larger voltage is created with capacitors attached to the MAX 232 (called a charge pump).
A "1" on a microcontroller might be +3 or +5 volts whereas the output of a MAX 232 might be -10 volts. And a 0 on the microcontroller 0 volts and the output of the MAX 232 +10 volts. So if you had a pin being used for CTS, you would set it to "0" to send CTS due to the MAX 232 signal being inverted.
And the signals for everything RS232 would need to go through a chip like that. TX, RX, CTS, RTS, DTR, DSR, etc.
Also you would typically use a "UART" or "USART" to do the actual sending and receiving of serial data, then the output of that going through something like a MAX 232 to get the right voltages.
More...
MAX232...
http://en.wikipedia.org/wiki/MAX232
RS232...
http://en.wikipedia.org/wiki/RS-232
UART...
http://en.wikipedia.org/wiki/Universal_asynchronous_receiver/transmitter
propeller
MAX2323
"real RS232-device"
nothing else is needed
best regards
Stefan
MAX2323
"real RS232-device" I think you might mean MAX3232 - a MAX2323 is an amplifier [noparse]:)[/noparse]
I've used both options. MAX232 with a 5V supply and 1k series resistor(s) for 5V to 3V translation.
Or MAX3232 running on 3V.
I think the cost works out about the same. Possibly the 5V one is a cheaper chip but it depends if you already have a 5V supply for something else.
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www.smarthome.viviti.com/propeller
http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,401,463&Prod=PMOD-RS232
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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
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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
Fascinating.
Yes, there are still times when real RS232 is required!
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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
Different beasts, for different purposes.
- digilentinc's is better for the pmod system, mine is better for prop users (has the reset circuitry)
- theirs is $5 more, but is assembled, mine is less, but a kit
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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