Incidious Propeller not Found

LoopyByteloose · 2013-07-21 13:39

I was making nice progress with several Propeller projects using bst in Mint Linux, but suddenly my SER2USB cannot locate a Propeller for programing purposes ONLY.

I can use the same device with Minicom to communicate fine with the same board at 230,400 baud via PropForth.
I have tried another Propeller Proto Board with the same SER2USB and am also shut out from downloads.
If I use a Propeller Demo Board with on-board USB, I have no problems with programing or Minicom.

Since the serial Tx and Rx are working nicely with the same board that the device refuses to program.. I can only guess that the Reset has failed somehow. Is that realistic?

I have an alternative RS232 to Propeller device that is home-brew that I have used in the past to program the Proto Boards, and so far that won't work either. But I may have built it to PropPlug rather than USB2SER pin outs.. have to dig a bit further.

Is there something obvious I am missing. I will start over in the morning.

Mike Green · 2013-07-21 14:27

The serial I/O itself seems to work. The reset operation does not. The homebrew RS232 interface won't program the Propeller either. That tells me that the problem is in the reset circuitry on the Propeller board. Maybe the connector has gone bad. Maybe a solder joint between the connector and the reset pin has gone bad. Can you write a program for your computer that opens a COM port and just toggles the DTR line? You'll need a pullup to 3.3V or 5V and you should see a pulse to ground on the positive going DTR edges.

LoopyByteloose · 2013-07-21 15:37

Thanks Mike,
I do have a Windows serial terminal program that will allow me to toggle the DTR pin ... and do a lot more to clearly investigate. It is called RealTerm.

http://realterm.sourceforge.net/index.html#Display_Formats

I had considered that it might be a cold solder joint, but I do have two boards that are not finding the USB2SER. Maybe I should dig out a third to try as well.

I suspect the connector on the USB2SER more than the boards... will look into a replacement for that. It certainly has gotten quite a bit of use and abuse recently.

Thanks...

Cluso99 · 2013-07-21 18:39

Occasionally under windoze I get the prop not found. It is something to do with the driver and windoze that doesn't like continuous USB resets (plugging the usb in and out) that seems to get lost. A full reboot of the pc is necessary sometimes.

LoopyByteloose · 2013-07-22 02:30

Resolved,,, but how or why remains a mystery.
I am using Linux Mint 15.
At times, there just seems to be temperamental USB regardless of OS

I did resolder the 4 pin connector's RST line on the USB2SER as it may have had a cracked solder joint... but it still didn't work last night.

I was prepared to do continuity testing today and even uploaded RealTerm to toggle the DTR with a LED if I needed to, but the USB2SER worked fine and programed two Parallax Proto boards without any complaint

franksanderdo · 2013-07-22 05:34

Hey Loopy,

this happens if you threaten electronics with repair efforts

Keep a todo list with the testing sequence sticking to your Computer and it will not fail again

No a bit more seriously:
I am not familiar with USB2SER but I would consider some broken wire as well as connector corosion.
Just to ad it on the todo list ;-)

Regards
Frank

prof_braino · 2013-07-22 06:58

I just had a weird batch of USB cables. They appear to work, but are loose or something. When they are touched, the prop starts or stops working. Could it be the cable or connectors?

LoopyByteloose · 2013-07-22 07:24

Cables? Maybe, but I did try switching them without any luck.

Everything suddenly worked fine with my first latte of the day. And then went wrong again as the day progressed. I suspect a thermal failure on the USB interface.

These intermittent electrical problems are the hardest to solve, but I am now thinking that my Toshiba NB250 is the problem source. There are no thermal sensors of these cheap notebooks, but it is old. I've had a replacement bought and standing buy for a year.

So I am switching over to another computer to see if all the problems go away.

Of course, this all happens when I am in the middle of a project that I am very motivated to finish... just to make one more crazy. Have to stop all the productive work and get the new computer set up.

prof_braino · 2013-07-23 11:32

Any results yet? I'm doing a workshop Saturday, and the participants are providing their own laptops, I don't know what junk they will bring in.

Did you try anything like moving the laptop next to the air conditioner, etc? Or did you pop it open clear the dusk off the heatsinks? I always find laptops are pretty nasty by the time I get them, sometimes to the point where the fans gets stuck from dust build up.

LoopyByteloose · 2013-07-24 09:40

What's happening?
Well, this doesn't seem to be a computer problem.

It seems mostly to center around my trying to use a USB2SER, Series A with some 5 volt RS422 chips. Maybe I broke it. Maybe it is on its last legs.

The USB2SER is a 3.3 volt device, even though it is powered by 5 volts at the USB power. The FTDI literature is a bit unclear if it is 5 volt tolerant or not. I just think I got one of the first and it may finally be on the way out. Parallax redesigned the i/o interface of USB2SER to Series B and C, so I guess they felt the first design wasn't quite 100%. I may have damaged the USB2SER by driving the RXD input with 5 votls, though there are 1K resistors protecting the TXD and RXD.

Series A RXD also has a pullup to 3.3 v on it. The Series B and C reduced the value to 150 ohms, has no pullup, and use later FTDI chips.

I suspect FTDI redesigned the TXD and RXD i/o to be more rugged in later silicon. Parallax followed along with a cleaner design.

At this point, it seems my USB2SER is working if I just don't fiddle with using it for the RS422 project. I begin to wonder if silicon has a way of healing itself.. as resting the device seems to have done wonders for it.

LoopyByteloose · 2013-07-24 10:44

Well, another reading of the FTDI FT232B pdf is revealing.
The chip will operate with 5 volt logic or 3.3 volt logic IF properly wired. But one has to wire it for one or the other in various segments. One pin provide +5 or +3.3 to the i/o. It looks as if that is wired to 3.3volts.

But the part that is disturbing it that the FTDI provides an internal 3.3VDC regulator that can be used as a source. The same regulation is providing 3.3v to the pullup on RXD that Parallax added. It seems that if I apply 5 volts to the RXD input, the pullup is working in reverse and feeding +5 in a small current into the regulators output. My past experienceswith running current backwards through a linear regular are complete disasters.

Not sure, may never be sure of how much damage was done... but it is obvious now that if I want an FTDI chip to drive 5 volt chips downsteam... a USB2SER or a other USB to Propeller device is not going to cooperate.

I need 3.3 volt RS422 chips to avoid trouble.... impossible to buy locally.

Incidious Propeller not Found

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