Propeller Serial Communication

bazz

Hello guys, is it possible to connect my propeller chip with max232 for serial programming?
i am thinking to use over the RXD line a resistor to limit the current for example

for Reception
max232 ----/\/\/\

---

> propeller

so R = (5-3.3) / 20mA

is 20mA acceptable or is too much??

and for transmission
max232

---

< propeller

or using those connections probably my propeller will get burned?

Help MEEeEEEeEEEEEeEEeeeeEEEEEEeEEEeEE

Rsadeika

The better solution would be to use a MAX3232, which is powered by 3.3V. I have used an RS232 breakout board, which has a MAX232, is powered by a 5v source, and used a 220ohm resister on the RX line. But, I think everybody else recommends a 1k resister.

Ray

Zap-o

Don't forget the reset pin on the propeller. It wont program with out it as far as I know.

Cluso99

bazz: Firstly, welcome. If you have any questions, please just ask.

Now to your questions which Ray has already answered. There is more information on the Parallax website with circuits for interfacing the Prop to the PC via USB and Serial 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

Dr_Acula

Sure, of course you can. Max232 = use a 1k resistor. Max3232 = no resistors needed.

The reset circuit is a transistor, capacitor and a few resistors.

I like the max232 because then you can use that serial port as a real serial port once it is programmed. Indeed, use the other half of the max232 as another serial port and use the object with multiple serial ports in one cog.

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www.smarthome.viviti.com/propeller

Toby Seckshund

Also

Using the MAX... chips will give you correct output voltage levels if you are connecting to other than a PC or its like. The transistor ccts, or the resistor only sort, rely on the negative/positive voltages supplied by the PC. So two of them wouldn't talk to each other properly.

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Style and grace : Nil point

bazz

1st of all thanks for your fast replies guys.

Now, i read about MAX3232 but maybe its difficult to find it on local market and also i think costs more than MAX232.
I have some spare I.C. MAX232..
Parallax site has a lot of information about propeller i know that, i study Propeller Manual v1.1 and Propeller Education Kit Labs v1.1
(i have a little experience using *8bit uControllers).
about RESn i am thinking the simplest connection using one push button wiring to the ground but maybe this is not correct at all.
When the button is pressed RESn = 0 and restart Boot Up procedure right?
but what happens when button is not pressed ?

Cluso99

A number of Parallax's pcbs have push buttons for reset (to ground). They work fine.

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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

stevehatch53

I have built several circuit boards and I thought I could just use the reset button and not install the transistor, but I found you can't push the button and get the right timing for the PC to sense the Propeller. After I installed the transistor, it worked great. I don't think you can get your Propeller connected without the transistor circuit in place. That was my experience. In all the propeller boards I now build, I use the transistor. The transistor is a 2N3904, a 10K resistor and a 10 nF capacitor. The PC uses the flow control pin DTR to reset the propeller. This is what establishes that critical timing.

Steve

Cluso99

Just in case you misunderstood my reply. The reset button only causes the prop to reboot. It does not synchronise it to a download. For that, as steve said, you will need the transistor circuit. I use a P2N2222A but be careful of the pinout as there are various forms.

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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

bazz

Some silly questions about the circuit


Is any problem if i use a 100nF capacitor instead of 10nF ?
What is the purpose of this capacitor?
What it will happen if i remove it?

Post Edited (bazz) : 2/19/2010 2:41:12 PM GMT

BigFoot

We use several 5 volt serial chips for RS232 & RS422 and a 4.7K resistor in series with
there serial data out line and the propeller input works fine.

There is no need to run allot of current through this line because the chips are all cmos
and have really low input currents.

Russ

bazz

Ok guys i spend many hours to get propeller work and the result was No Propeller Chip Found on any serial port.
I try a few circuits but no results at all
last one i was testing is this one

it is also recommended on propeller's databook
i double check everything and nothing ...
if i have time i will draw my circuit to see what i have done so far
i also replace the chip with a new one but still no connection

using a multimeter i read those values

Rx(P31) line i get 3.32V
Tx(P30) line 2.7V

and RESn 3.45V *(i read the same value if it is unconnected)

please guide me

Cluso99

bazz: Your main problem is likely to be with the Res section as it is probably not resetting the prop. The 10nF is part of a time constant with the 10K from base to ground. It delivers a reset pulse to the prop. My circuit from an FTDI does not have the series 10K to the base.

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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

bazz

I think i did something terrible wrong ..
with your circuit Cluse for DTR(+12/-12) connect to 2n2222a base and using a *capacitor and **resistor as your circuit
Collector stay at 0Volts .Toggle the DTR pin using Serial Terminal the output still the same.And the question is WHY ??
I don't have 10nF right now.
*100nF
** 10K