Firecracker and USB-Serial

In trying to get this combination to work on my Mac with heyu, I've
discovered that DTR is never going high. With a 'scope, I can see the
"1" signal on RTS pulsing merrily, but the "0" signal on DTR never
moves. Which probably explains why the Firecracker isn't working...
Can anyone shed any light on this problem? I understand that some
USB-Serial adapters won't work with the Firecracker, but I never was
able to find out precisely why (though there seemed to be an assumption
that it had to do with "low signal levels"). That is not the case here
-- the signal on RTS swings a full 5 volts.
Could it be my cheap no-name USB-Serial adapter? Or the open-source
driver I'm using?
Does anybody have a Firecracker working with a USB-Serial? What brand,
and which chip does it use?
thanks
Isaac
Reply to
isw
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It has been a few years since we discussed this (and my memory isn't as good as I remember it being) but Charles Sullivan, who maintains heyu, has done extensive testing of numerous USB-Serial adapters. If he doesn't see this thread, you should try contacting him via email or through their users forum. See...
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for both his email address and a link to the forum.
Knowing the chipset is not a guarantee as some adapter makers have not made use of all of the features of the chipset. I believe that all FTDI chipsets and the Prolific PL2303 control/report all of the lines but I haven't done hands-on testing in several years.
I think you can trust both of these...
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but, IIRC, Charles said the Y-105 did not handle RI, while the Byterunner web page indicates both it and the USB-COM-CBL (FTDI based) I cited above do and I've always found Sean Dudley at ByteRunner both knowledgeable and reliable. Anyway, you do not need RI for the Firecracker.
Finally, both FTDI and Prolific have drivers for OSX and I believe there are links to both on the Byterunner product pages. If not, send an email to Sean Dudley (see the Contact link). It might be worth trying the OSX driver with your current adapter before buying another.
isw wrote:
Reply to
Dave Houston
"isw" a écrit dans le message de groupe de discussion : isw-DA72EE.21034411102010@[216.168.3.50]...
Dont know if the firecracker need more then 5 volt, but if I am right the voltage for rs232 are supposed to be -12 to +12 volts..not 0 to 5 volts..
Reply to
petem
Different RS-232 spec.
There are two RS-232 specs. RS232C and RS232. Different voltage limits are allowed. % volts is just fine for one
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If you are not using DB25 connectors do not call it RS-232, call it serial interface.
Now you have to specify DTE or DCE to specify what connector you are using.
Dont know if the firecracker need more then 5 volt, but if I am right the voltage for rs232 are supposed to be -12 to +12 volts..not 0 to 5 volts..
"isw" a écrit dans le message de groupe de discussion : isw-DA72EE.21034411102010@[216.168.3.50]...
Reply to
Josepi
The Firecracker has only a small PIC, using a couple of its pins for a software UART - there is no level converter chip so 5V is just fine. There are current limiting resistors in its send/receive lines so standard RS-232 voltages are OK, too as the PIC has clamping diodes on its inputs.
"petem" wrote:
Reply to
Dave Houston
The spec does not specify voltages, only ranges. And there is a "legal" method for making 0 and +5V work just fine. A problem *could* arise if one end of the link assiduously adhered to the +/- 12 volt swing *plus* the rarely used hysteresis offset, while the other end used 0/+5.
Isaac
Reply to
isw
Plenty of "non-RS-232" interfaces use DB-25s.
The connector is the same; the pinout is different -- sort of. And things really get confusing when you consider devices that can act as either DCE or DTE (like many computers). In that case, there's no *right* way to wire up the connector...
Isaac
Reply to
isw
There is also RS232D, which specifies a pinout for RJ-45 connectors.
I just remembered a couple of things. (I guess it's true that the first thing to go is short term whachamacallit.) System Profiler will report details on the adapters, even without the drivers installed. You _may_ be able to ID the chipset. And, it doesn't cause any problems to install USB drivers w/o having the target device attached. In one case (Mini - Intel), I installed the drivers while still hunting for my hardware. In another (iMac - PPC), I connected the hardware and forgot I needed the drivers until noticing no ports showed in /dev - for that, you need drivers. While your problem seems to be that the manufacturer of your adapter failed to implement DTR, it might be worth trying both FTDI & Prolific drivers with your adapter on the off chance it's your driver. Can you uninstall the current driver? (The Mac is still mostly terra incognito for me.) I'd be concerned about it conflicting with the FTDI or Prolific driver, if not.
Anyway, I'm sure the Y-105 handles DTR and at $8 + first class postage, it's certainly economical.
isw wrote:
Reply to
Dave Houston
I have spent many tears trying to make things standard with this nonsense.
If the correct connectors are used for the application the interface always works, everytime.
It is only the confusionists that cannot follow specs that make RS232 not work, ever.
The connector is the same; the pinout is different -- sort of. And things really get confusing when you consider devices that can act as either DCE or DTE (like many computers). In that case, there's no *right* way to wire up the connector...
Isaac
Plenty of "non-RS-232" interfaces use DB-25s.
Reply to
Josepi
The spec specifies voltage minimums and maximums. You just have to stick to the spec being used.
The spec does not specify voltages, only ranges. And there is a "legal" method for making 0 and +5V work just fine. A problem *could* arise if one end of the link assiduously adhered to the +/- 12 volt swing *plus* the rarely used hysteresis offset, while the other end used 0/+5.
Isaac
Reply to
Josepi
Isn't that irelevent? Just because other interfaces have usurped use of the DB25 connector doesn't relate to the fact that RS-232 specifies a DB-25 connector (hence if it isn't a DB-25 it isn't RS-232).
Well, the DCE side is a female DB-25 connector and the DTE side is a male connector. This should make the pinout unambiguous.
Reply to
marcus hall
So what do you do with a computer, which can be either? And don't forget all the pin-swaps...
Isaac
Reply to
isw
I know it's a Prolific chip -- it sort-of works, which it would not at all with the FTDI driver. And I've tried both the Prolific driver and the one on sourceforge. As of right now, neither one seems to be doing a wonderful job, but I haven't finished poking around yet.
Isaac
Reply to
isw
Well, the computer is wired as a DTE and has a male connector. To connect to a DCE device, you simply use a straight through Male-Female cable. If you want to connect to another DTE device, you use a null-modem Female-Female cable. The real trick is how you cross-connect the signals in the null-modem cable, though, and which signals each DTE asserts when idle and which signals it expects to start the conversation.
Reply to
marcus hall
Just buy the apropriate cables and if they plug in they work. All the confusion was created by those not understanding that the IEEE EIA-232 was defined within an inch of it's life. No hammers for the connections though.
Next we can get into signal lines that everybody wanted to violate...LOL It gets complicated by, again, **sigh** the companies that wanted to break out on their own.
Well, the computer is wired as a DTE and has a male connector. To connect to a DCE device, you simply use a straight through Male-Female cable. If you want to connect to another DTE device, you use a null-modem Female-Female cable. The real trick is how you cross-connect the signals in the null-modem cable, though, and which signals each DTE asserts when idle and which signals it expects to start the conversation.
Reply to
Josepi
"Josepi" ...
What a load-O-$^&%
I spent a number of years working on combining many instruments from many makers into automated test systems and was the defacto company interface guru.
When something says it is an RS-232 serial port, that is just a hint to starting the connection issues. The IBM PC serial cards really helped straighten out the mess because many companies decided that it was the most common and well documented version. There is still a lot of equipment that swap the lines or only use odd combinations or none of the handshaking lines. Many also use improper voltages even though the chips to add the proper voltages are cheap.
Reply to
Bill Fuhrmann
Reading comprehension problems?
You had problems because the equipment manufacturers don't stick to the defined IEEE standard.
Your "guru" status may have been misplaced or self acclaimed.
I have been there also and it is a mess. Now they are doing it with Ethernet and USB.
"Josepi" ...
What a load-O-$^&%
I spent a number of years working on combining many instruments from many makers into automated test systems and was the defacto company interface guru.
When something says it is an RS-232 serial port, that is just a hint to starting the connection issues. The IBM PC serial cards really helped straighten out the mess because many companies decided that it was the most common and well documented version. There is still a lot of equipment that swap the lines or only use odd combinations or none of the handshaking lines. Many also use improper voltages even though the chips to add the proper voltages are cheap.
Reply to
Josepi
No reading comprehension problems. I addressed that the standard is insignificant because it is violated to such an extent that it is useless.
Saying "Just buy the apropriate (sic) cables and if they plug in they work." without qualifying it that this is in case the vendor just happens to follow the official standard, when you know that they don't is a load of crap.
I suppose that you would also be willing to say "following the speed limit means you won't get passed."
Reply to
Bill Fuhrmann
Obviously we both understand what is happenning. MY RS-232 connections always work. If they don't I permanently adapt them to the standard.
Attempting to increase the bandwidth of the argument is probably only trolling and fruitless. I didn't see your base disclaimer and you didn't see mine. The importance is insignificant at this point.
All the best.
No reading comprehension problems. I addressed that the standard is insignificant because it is violated to such an extent that it is useless.
Saying "Just buy the apropriate (sic) cables and if they plug in they work." without qualifying it that this is in case the vendor just happens to follow the official standard, when you know that they don't is a load of crap.
I suppose that you would also be willing to say "following the speed limit means you won't get passed."
Reply to
Josepi

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