Whow, Andre, thank you for this comprehensive answer. I hope more people than me alone will benefit from this.
Mit freundlichen Grüßen / Regards Horst Rupp Schillerstr. 38 64407 Fränkisch-Crumbach mobile 0171 6226 909 -----Ursprüngliche Nachricht----- Von: Schoen, Andre [mailto:andre.sch...@siemens.com] Gesendet: Freitag, 22. Juni 2012 14:37 An: Horst Rupp Cc: xcsoar-user@lists.sourceforge.net Betreff: RE: [Xcsoar-user] IOIO Card Freezing up Copying from Wikipedia: - Valid signals are plus or minus 3 to 15 volts; the ±3 V range near zero volts is not a valid RS-232 level - A TTL input signal is defined as "low" when between 0 V and 0.8 V with respect to the ground terminal, and "high" when between 2.2 V and 5 V[18] (precise logic levels vary slightly between sub-types and by temperature). TTL outputs are typically restricted to narrower limits of between 0 V and 0.4 V for a "low" and between 2.6 V and 5 V for a "high", providing 0.4V of noise immunity. This is the standard TTL, the CMOS version varies slightly. As you can see, both RS-232 and TTL have "dead bands", if the voltage drops into that range, the logical status is undefined (and you might get a lockup). What has worked for me in the past, was opening them and add an additional RC filter in the power supply of the offending device, to guard against surges (both from the power supply or the data circuits). Had a problem with a cheap 12V to USB convertor for an old pocket PC (device kept resetting), and that solved the problem. For a low power level shifter, a 10 Ohm (1/4W type is sufficient) resistor on the 12V power supply input (in series) should work. With a typical 50mA load that gives you only a voltage drop of 500mV (i.e. still acceptable) and a large capacitor, say 50uF electrolyte(or larger if space permits), would give you a 0.5ms buffer for input spikes and approx. 10msec on the supply side. Solder the capacitor in parallel, after the resistor to ground - it acts as kind of a short term battery (watch polarity). Have not looked at the IOIO circuits, but I would assume that its power circuits will have a good sized capacitor/power filter, i.e. should not need extra protection, as long as the leads powering it and particularly the connectors make good contact. High resistance from corroded contacts could negate that. Keep data leads as short as you can, to avoid cross talk (and keep away from the radio, or use shielded data cables). Although this should be of a lesser issue at those baud rates and distances. Regards, Andre -----Original Message----- From: Horst Rupp [mailto:ho...@rupp-family.de] Sent: 22 June 2012 12:38 To: Schoen, Andre Cc: xcsoar-user@lists.sourceforge.net Subject: AW: [Xcsoar-user] IOIO Card Freezing up Thanks, Andre. I assumed the signal level shifter RS232 -TTL in front of the IOIO box would possibly garble up the signal stream so that the IOIO board falls off track and cannot establish the communication stream again. After reboot of the IOIO board alone communication comes on-line again. The overall power supply in my setup is certainly ok, that has lots of overkill. But I have bought cheap assembly sets. So it might be possible that these sets falter when there is too much data traffic. The baudrate is 19200. So I have to cherish your advice and buy the best possible hardware - for the second generation of IOIO boxes. Mit freundlichen Grüßen / Regards Horst Rupp Schillerstr. 38 64407 Fränkisch-Crumbach mobile 0171 6226 909 -----Ursprüngliche Nachricht----- Von: Schoen, Andre [mailto:andre.sch...@siemens.com] Gesendet: Freitag, 22. Juni 2012 12:57 An: Horst Rupp Cc: xcsoar-user@lists.sourceforge.net Betreff: RE: [Xcsoar-user] IOIO Card Freezing up Do you mean a signal shifter for different supply voltages, or to adapt data signal levels / protocol converter? In either case, they will have filters and capacitors to cover for power surges (either from the board supply, if wiring is not very good, or when transmitting a lot of data, which can cause spikes if the power supply filter is of a marginal design). The better ones of course have better filters/drivers. With signal interfaces, there is also the question of signal levels (and to a lesser extent current), the standards allow for some tolerance, if your device works very close to the minimum standard, then any deviation (power surge, heat effects, etc.) are more likely to cause problems. Problem meaning that the signal level is out of spec and wrongly interpreted by the device, sending erratic messages, causing the software to freeze. If you have an oscilloscope, you could try to measure and compare against the standard. A crude way could be to just measure with a voltmeter, to see if at least the static signal is within spec. Don't know the input impedance of the IOIO board, but if it drains a good amount of current, then you are running the shifter at its limits (with the better ones having drivers for higher currents). With signals out of spec, a firmware change won't help much, other than maybe prevent a freeze if input data is garbage or the hardware has locked up. -----Original Message----- From: Horst Rupp [mailto:ho...@rupp-family.de] Sent: 22 June 2012 11:11 To: xcsoar-user@lists.sourceforge.net Subject: Re: [Xcsoar-user] IOIO Card Freezing up Hi all, this is a reply to my own post and a call for advice. When soldering up my level shifters, I fortunately did build a couple of them, not only the two needed for the IOIOBox. With a substitute level shifter my freeze-up problem becomes much more rare. Beforehand I had a freeze-up within minutes to 2 hours after starting the communication. Now, with another level shifter, the interval is 8 - 10 hours. These are cheap level shifter, bought on-line for less than 6 Euro. To me this looks like violation of tolerance limits of signals exchanged between level shifters and IOIO board. Unfortunately, I have no equipment to check that. And being more a software than a hardware guy, I am not sure I would find something. However, could that be the reason ? Or is the reason for the freeze-up tied to intolerances of signal treatment in the IOIO board ? Would it be worth while to dig into firmware versioning of the IOIO board (which I would like to avoid) ? Any idea around ? Would be great to hear something. Horst ----- Horst Rupp aka 1R www.how2soar.de -- View this message in context: http://xcsoar.1045713.n5.nabble.com/IOIO-Card-Freezing-up-tp5457507p5709841. html Sent from the xcsoar-user mailing list archive at Nabble.com. ---------------------------------------------------------------------------- -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. 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