Parallax question: Using the PropTool with two Props

Harley

A. Presently I am using a PropSTICK using serial COM 1 port, and a DIP-40 Prop using COM 4, using the PropPlug.

Is there a way to have the PropTool 'know' which port is used when one switches between programs?___

Hopefully there is a way to handle this dilemna. Otherwise there is unnecessary wear and tear on the DB9 and USB connector contacts; and the operator. Working with two props sometimes means making changes in each program and continually having to switch in/out the programming i/f's.

B. And regarding the PropPlug, what should be done with the Tx, Rx and /RST Prop lines when PropPlug is NOT attached?___ Figure 1-1 of the Prop manual indicates no pullup R necessary. Unused port pins, I assume, should be pulled up. Would it be improper to connect both /RST pins together in a multi-Prop design?___

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Harley Shanko
h.a.s. designn

Paul Baker

Sorry I didn't answer your earlier posts Harley. There is no direct way of doing what you want, this feature is a candidate for a future release. There is however a work around for what you want:

• Start the Propeller Tool, open the project for the first Propeller.
• Power and plug your first Propeller into the programming port
• Go into Edit>Preferences and click on the Files and Folders Tab.
• Uncheck "Associated files launch into single editor"
• Press F7 to identify the first Propeller
• Power down or disconnect the first Propeller
• Double click on the project spin file for the second Propeller within Windows Explorer (not within the Tool)·
• This will start up a second instance of the Propeller Tool.
• Power·and plug your second Propeller into the programming port
• Press F7 to identify the second Propeller
• Connect/Power up the first Propeller

Now each Tool will first check the last known·Propeller port, as long as both are powered and plugged into the port, each instance of the Tool will remain connected to each Propeller. If you attempt to program and the respective Propeller·doesn't respond, it will discover the other Propeller and program it. In this event·you will have to·repeat the above process.

If your intention with connecting the two /RST lines together is to use a single reset switch to get both Propellers reset simultaneously, you should instead use a DPST N-O·momentary switch. The two /RST lines should not be connected together because they are actively driven by the two programming devices.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Post Edited (Paul Baker (Parallax)) : 11/17/2006 12:44:34 AM GMT

Harley

Thank you Paul. I felt I'd included too many different questions, after thinking about it. So re-worded it.

I will try your suggestion of setting up two instances of the Propeller tool. That may help greatly with the situation.

My reason for asking about connecting the two /RST pins was because a SPST switch already exists on a board the two Props will i/f with. I suppose I could use a separate resistor in series with the switched line to each Prop /RST pin. There is comm between the two Props, but didn't want the init delay to add up any more than a single Prop's initialization delay presently is.

Looks like A31 (Prop pin 40) should be pulled up or down for when the PropPlug is not used. Else the CMOS input will float; or is there a weak pullup/down in the Prop?___ I'm just wondering if a pin should float.

The /RST pin appears to be pulled up internally. Is that correct?___

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Harley Shanko
h.a.s. designn

Jeff Martin

Just a quick note:

The "Associated files launch into single editor" should be unchecked and then the Propeller Tool closed (because it doesn't save those settings until closed). Then two or more instances of the same Propeller Tool can be started in the way described above.

It's okay for A31 to float; it's not pulled high internally, but the Propeller chip is able to determine that there is no host present, regardless.

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--Jeff Martin

· Sr. Software Engineer
· Parallax, Inc.

Paul Baker

Thanks for the clarification Jeff. The /RST pin is pulled high internally.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Harley

Thanks Jeff and Paul ................. for the information on working with two Propellers.

If I power-down the Props, will the PropTool lose track of which Prop they've been set up?___ Many times I need to power them down; hopefully they won't lose that info.

Including a shot of the present protoboard setup. Using TV_text for debugging, a 1 A switching power module for 5v power for the PropSTICK which powers the Prop2, and interfaces with an existing pcb via the ribbon cable. (I'm not the neatest wire guy; apologies to the purests.)

That board has a SPST switch with 1N914 diode and 10K pull up R to 5v used to Reset the whole system, if needed. I was planning to use 10K resistor to Prop /RST pins. However, I measured the /RST pin current to ground with a multimeter at approx. .33 ma; that appears to be about a 10K pulllup internally in the Propeller. Is that about correct?___ I probably should make the current limiter R value 4.7K or lower to guarentee a /RST level below the threshold.

The other side of the system, the Props have 13 and 22 interfaces to 5v TTL logic. The schematic presently is using 1K value, but that probably should be made larger so as to not sink too much current into the Props. Is there a figure as to how much total or per pin one should limit current into a Prop?___

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Harley Shanko
h.a.s. designn

Paul Baker

Harley said...
Thanks Jeff and Paul ................. for the information on working with two Propellers.

If I power-down the Props, will the PropTool lose track of which Prop they've been set up?___ Many times I need to power them down; hopefully they won't lose that info.

if you dont try to program the disconnected Propeller.

Including a shot of the present protoboard setup. Using TV_text for debugging, a 1 A switching power module for 5v power for the PropSTICK which powers the Prop2, and interfaces with an existing pcb via the ribbon cable. (I'm not the neatest wire guy; apologies to the purests.)

That board has a SPST switch with 1N914 diode and 10K pull up R to 5v used to Reset the whole system, if needed. I was planning to use 10K resistor to Prop /RST pins. However, I measured the /RST pin current to ground with a multimeter at approx. .33 ma; that appears to be about a 10K pulllup internally in the Propeller. Is that about correct?___ I probably should make the current limiter R value 4.7K or lower to guarentee a /RST level below the threshold.


Im not quite following your setup, so I cant answer your question.

The other side of the system, the Props have 13 and 22 interfaces to 5v TTL logic. The schematic presently is using 1K value, but that probably should be made larger so as to not sink too much current into the Props. Is there a figure as to how much total or per pin one should limit current into a Prop?___
the Propeller can take alot of abuse, but shouldn't be if you want a long life out of it. Check out the sticky thread regarding interfacing with 5V signals.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Harley

Again, thanks so much for the advice.

I'll reword the point that wasn't clear. The reset switch on another board, when closed, the Prop will see ground through a silicon diode, say 0.6v level. If the Prop has about a 10K pullup value internally, the current limiting resistor should be such that the Prop sees less than 1/2 of 3.3v (= 1.65v), right? My mention of using a 4.7K, on recalculation, biases the /RST to about 1.46v, a bit too close to the threshold. So it should be even lower, maybe a 2.2K. That other board uses a 10K pullup, so it isn't like being driven by 5v TTL logic.

I think I've got it figured out now. I just didn't want to 'hurt' the Prop. But after reading Chip's 1.5W 'cool' chip, it sounds sturdier than I'd of imagined. I suppose the only thing I need to worry about is not pulling out of regulation the 3.3v output with 35 some current limiting resistors to 5v logic.

The Propeller is one neat chip to work with. I'm impressed.

One more question; my PropSTICK responds with a CHIPVER = 1. Are there any other version numbers?___ My second Prop appears to be '0'; is that possible?___

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Harley Shanko
h.a.s. designn

Paul Baker

The reason the /RST is pulled up to 3.3V internally is so an external resistance isn't needed. Any voltage lower than the threshold can be directly applied. When coupled to a 5V non-active reset signal a 1kOhm series resitor is sufficient to protect the pin.

If your communication rate is low, you can raise the series resistors to limit the current. The series resistor coupled with the input capacitance of the pin (in the vicinity of 10pF) forms a low pass filter, which inhibits the speed of the communications. To be sure this isnt happening you can set the resistance according to R=1/(4 pi f_c C) where f_c is the communication frequency. This assures that two RC time constants occur in a communication cycle, or that the end value achieved will be 86.5% of it's final value.

No, it is not possible for a Propeller to return a version of zero, all Propellers currently availible respond with 1.


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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Post Edited (Paul Baker (Parallax)) : 11/18/2006 1:09:35 AM GMT

Harley

Thank you Paul,

The comm rate is 38.4 kbaud. I understand about the RC effects here. This hasn't been any problem. But will keep it in mind as some other signals are much swifter.

Is there yet a 'data sheet' on the Prop for the threshold levels on the various pins; I/Os, clock, /RST?___ I'm used to working off data sheets; hadn't yet seen anything in that direction.

I realize putting out such a document as the manual is a huge task. Maintaining accuracy of info is quite an effort also. And a data sheet involves loads of testing and time. Probably a number of user's questions would be answered by a data sheet. But costly to get one in a form for users. Thanks.

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Harley Shanko
h.a.s. designn

Paul Baker

It's in the works, I am testing the parameters, haven't gotten to thresholds yet.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Harley

Thanks Paul.

That was a quick response. OK, so we have that to look forward to. Maybe 1st or 2nd quarter 2007, or sooner?

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Harley Shanko
h.a.s. designn

Paul Baker

Plans are for Preliminary this quarter, full in next.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.