Programming the Prop Chip via RS232 Interface, Help advice please.

Dr Bulb

·Hi Guys
············· Newbie to this forum which looks great from a quick read. Can any of you guys answer this question, Do I need a straight through or a crossover/ null modem
· cable, for basic RS232 comms?· I am using a simple null modem cable pins 2 and 3 tx to rx crossover, pin 4 DTR for reset and 5 for ground on·9 way D sub. This is going
· through Maxim 3232 for level conversion then to pins 39 and 40 of Propeller Chip. After much messing and guessing with my scope I still get no propeller chips found on my··
· known working COM1 port, which will echo back with a link on my veroboard prototype to a terminal emulator. Just don't understand how Prop Tool talks to the chip except·
· reset pulse being supplied by DTR, which I am using a one transistor circuit for. Also I am using an external crystal on pins 30 and 31, but assume at reset prop chip uses
· internal osc for startup and basic comms ??· Cannot wait to get using this chip it looks incredible, so any help would be much appreciated thank you.

Post Edited (Dr Bulb) : 1/3/2010 12:52:02 PM GMT

Cluso99

Firstly, welcome.
Next, please update your subject using the pencil icon on your post to edit it.

Now for your problem. Their are circuit diagrams of what you are trying to do on the Parallax website. Do you have the DTR circuit with the transistor + resistors and capacitor? See the PropPlug circuit for this (Parallax websites, from the store, find the item, and there will be a schematic)

Forgot: Yes the prop uses the internal osc to boot which includes the download.

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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)
· Search the Propeller forums·(uses advanced Google search)
My cruising website is: ·www.bluemagic.biz·· MultiBladeProp is: www.bluemagic.biz/cluso.htm

Mike Green

1) It's very important to include a subject when you start a thread. Use the pencil icon in the upper right hand corner of your first message to edit your subject.

2) You need a straight through type of connection for your serial connection. Look at these diagrams for the connections needed: www.parallax.com/tabid/254/Default.aspx

3) During bootstrapping, the Propeller does use its internal clock

Dr Bulb

·· Thank you Cluso99 and Mike Green, for a very swift response much appreciated. Yes regarding subject for my posting I realised as soon as I had posted it their was no subject Doh! I searched for a way to edit my post, but did not realise that you used the pencil to do it thank you, subject now on. Right thats a good start from you guys a straight through connection is required. I will follow up the info you have provided and will post again with my results. Yes Cluso99 I do have a DTR circuit the same as the PropRPM boards circuit, see http://elmicro.com/proprpm.html for a look at the schematic. Great forum guys many thanks again.


Post Edited (Dr Bulb) : 1/3/2010 1:05:49 PM GMT

Dr_Acula

Sounds like you are very close. I use a max232 and a single transistor on the DTR line. Tested with a real serial port on an older PC, and with a generic $3 USB to serial adaptor I got off ebay.

I suspect the problem is "I am using a simple null modem cable pins 2 and 3 tx to rx crossover,"

The circuit does not cross over.

Your real serial or serial adaptor will probably be a D9 male. Data comes out of pin 3 on a male D9. Resting is -9V.

I'm just looking at your schematic. I think it all should work if you have pins 2 and 3 not crossed. You can double check that by putting a logic probe on physical pin 40 (P31) of the prop and try a download and you should see it go from resting 3V to pulses of 0V as the data goes through.

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www.smarthome.viviti.com/propeller

Post Edited (Dr_Acula) : 1/3/2010 2:10:27 PM GMT

Toby Seckshund

Occationally my props pretend to absent, on the first time of trying to do something. On the second attempt they wake up.

I use the three transistor version, but I have built one MAX3232 and a transistor type too. That worked after I got the P30 and P31 pins the right way round.

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Style and grace : Nil point

Dr Bulb

· Yes I have got my Propeller chip running and flashing a led on P16, thats one small step for man and a giant relief for me. Many thanks to you four guys who replied to me with the very information I needed, just got a program loaded into the serial eprom and it is·running fine. How have I resolved it with your help?· Made my own straight through DB9 to DB9 serial cable·using two female DB9 sockets connected 2 to 2, 3 to 3, 4 to 4, 5 to 5. Tried prop tool and still got no prop chips present, got the scope on it and could see that TX out on pin·7 of MAX3232·chip on my prop vero prototype was nothing like an RS232 level signal. Turned out to be a tiny whisker of copper between pin 7 and pin 6 one of the caps for the voltage pumps on MAX3232 chip. Ahh! the joys of stripboard! this was obviously due to the spot face cutter. Chip is detected perfectly now and can load ram or serial eprom, I am very pleased even though it is 1:05 am UK time who cares we have the hello world led program to stare at now until 4am · I will tidy up my comms portion of the circuit that uses MAX3232 and one transistor and post it here, for anybody else who has similar problems to me. Again thanks again guys and it is good to be a member of such friendly forum. All the best for 2010 to all.

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It began with a closed deserted diner and a man to tired to debug his Z80 code any longer.

Dr Bulb

·Hello all
··········· As promised attached is a copy of the circuit I am using for communication between Propeller Tool on PC and Propeller Chip. Firstly the circuit is based on the PropRPM board see this link http://elmicro.com/en/proprpm.html, so all due respect to them. I have removed one resistor 10K between the 10n capacitor and the transistor base on the DTR reset circuitry and it works fine. Also the detail of the straight through DB9 to DB9 cable was provided by guys on this forum thank you, I have just drawn it out so the whole circuit is the complete solution. This is cheap to build and I hope it saves other Propeller Newbies the problems I encountered. My endevours are not for gain in any way, electronics is my 30 year passion. Not the neatest of diagrams but should convey the required info. Just wanted to give something back to this excellent forum.

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It began with a closed deserted diner and a man too tired to debug his Z80 code any longer.

Dr_Acula

That looks good. The parts in that circuit would only cost $2, which works out cheaper than a prop plug. Plus less mysterious. And if you don't have a serial port you can just get a usb to serial adaptor for another $2 to $3.

If you wanted another serial port, you could feed the DTR line directly into the transistor using that resistor you left out, and that leaves the other half of the 3232 free which can go to another two propeller pins. DTR is switching via the blocking capacitor so it is switching on transients. I'm not 100% sure of the polarity of the reset as the 3232 inverts and the transistor inverts again but if it is working then that is all that matters.

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www.smarthome.viviti.com/propeller

Dr Bulb

·Thanks Dr_Acula

······················ Yes I agree with you after wrestling to get my prop chip talking to Propeller Tool, it was worth it and thanks to guys like you for your feedback. That interface works 100% so as you say no more mystery to getting code into your prop chip and as you say the cost is low and I like your expansion ideas. Your CPM project looks very interesting must have a look again when I get more experience with prop programming. I come from Z80A and Pic background so the prop is a new learning curve, what no interrupts? This chip is going to be fun to grapple with and is a brilliant piece of design, hats off to Chip Gracey and team. I scoped pin 11 of prop chip whilst pressing F7 in Prop Tool and the reset pulse is negative going, with a sharp falling edge and an expotential rising edge obviously due to 10n cap. Good luck with your project.


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It began with a closed deserted diner and a man too tired to debug his Z80 code any longer.

Post Edited (Dr Bulb) : 1/7/2010 1:47:27 AM GMT