What Is the Processor in Ccsu After Coming Back Again

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picprogrammer Joined: 10 Sep 2003 Posts: 35	Tin a cpu habiliment out? Posted: Mon Jul 30, 2018 4:03 am Of class y'all recall incommunicable. But what happens here. I take got a large network using Tin running for viii years now and sometimes new modules are added most are unchanged for years. A few months ago one unit did not receive any Can information anymore. Bad commuter or wiring was suspected. But later on some debugging it seems after receiving 1 Can message no more messages were received anymore. Replaced the 18F2680 and original old software and OK. I'thou running the internal oscillator. This week I have 2 modules LCD connected to I2C with bug. They collect data from Tin and show information technology on the LCD, new data every 3 seconds. Again the 18F2680. Both a few days in between did not update the information on the display. After a power cycle they did work again merely later on a few hours stopped again. On the series debug power I saw a watchdog timeout repeating. After a lot of debugging it seems it was stopped on the command i2c_write(data) a crash and watchdog comes in. After reboot this repeats itself and simply possibility to escape is power cycle. The I2C slave seems not the problem I replaced the I2C LCD and in the reboot situation the I2C data line was high. A new 18F2680 and both working fine for a some days at present. Do these cpu's wear out?
Ttelmah Joined: 11 Mar 2010 Posts: 17724	Posted: Mon Jul 30, 2018 4:33 am The commonest components to 'wear out' are capacitors. Especially electrolytics. Effort looking very advisedly at the supplies. Y'all may observe that ripple has got worse and this is causing a CPU failure that the 'sometime' flake just happens to be particularly susceptible to.... Semiconductors practice degrade, particularly if run 'hot'. By and large far more probable at normal Picture show temperatures though are other failure mechanisms, such as humidity resulting in corrosion on legs, and penetrating along the legs into the package. This can then event in semiconductor failures. Older Motion picture's with larger die sizes have longer expected lives, than more modern types. Even so for case, a 'forty year' expected lifetime, if you have a thousand devices implemented, may withal have y'all finding individual devices failing after 'only' 10 years. The almost likely component to fail in the Flick is the program retentivity. Depending on the environment, you may well exist suffering from an oxidation failure propagating along the legs into the packet. At this timescale you are unlikely to exist experiencing an electromigration failure. Other things that can advance failures are if the device is close to something giving small-scale levels of atomic radiations. Fifty-fifty an former 'radium' luminous dial can give a quite significant dispatch in IC failures...
newguy Joined: 24 Jun 2004 Posts: 1779	Posted: Mon Jul 30, 2018 6:04 am Did I read correctly that yous have a network continued via CAN and the processors are running from their internal oscillators? While it's true that modern PICs accept really quite good internal oscillator accuracy, I still wouldn't feel comfy using it on a CAN network. Can function of your issue be explained by clock migrate?
Ttelmah Joined: 11 Mar 2010 Posts: 17724	Posted: Monday Jul xxx, 2018 seven:xv am I hope he is not using the internal oscillator for CAN. Even the best Moving picture internal oscillator is an lodge of magnitude outside the required specs for fifty-fifty quite low speed Tin can, even more than so if the bus frequency is higher...
temtronic Joined: 01 Jul 2010 Posts: 8384 Location: Greensville,Ontario	Posted: Mon Jul xxx, 2018 7:21 am yup.... I'chiliad running the internal oscillator. even I (the old guy) use a real xtal/caps for high speed(9600+) serial. CAN is real darn 'fussy' nigh it's clock !!!
Ttelmah Joined: 11 Mar 2010 Posts: 17724	Posted: Monday Jul 30, 2018 7:34 am Yeah. Even at 125KHz, the required tolerance is just under 1.25%. Even at 25C, the internal oscillator on this Picture show only manages +/-2%. While for a reasonable temperature range it is +/-5%.....
picprogrammer Joined: 10 Sep 2003 Posts: 35	Posted: Monday Jul 30, 2018 7:36 am Aye i'g running 125khz CAN on internal oscillator. >twenty different units. This tin can be problematic i know bit this cannot explain why afterward exactly 1 message never whatsoever will exist received.
Ttelmah Joined: 11 Mar 2010 Posts: 17724	Posted: Monday Jul thirty, 2018 7:57 am Long term drift in the oscillator.... Remember this is resistor/capacitor based. It derives from an internal gate that is laser trimmed at manufacture. It sounds to me every bit if this is now globe-trotting off significantly as the bit warms up. So works only for a few minutes after boot, and then gets a massive failure rate.
picprogrammer Joined: 10 Sep 2003 Posts: 35	Posted: Tue Jul 31, 2018 four:39 am The internal oscillator may be not a smart idea but if the drift was the problem it would happen no messages were received or sometimes a few. This cpu stop later exactly i message. The I2C trouble with locking cpu on the i2c_write has nothing to do with a drifting oscillator. Even a watchdog reboot does not solve this. If the slave device is the problem the i2c_write returns no ack.
Ttelmah Joined: eleven Mar 2010 Posts: 17724	Posted: Tue Jul 31, 2018 4:50 am An I2C device that holds SDA depression, tin hang the master. This has ever been an issue with I2C, which is why sensible coder's check the SDA line is loftier before starting an I2C transaction. The recovery for this is to pulse SCL repeatedly, which is meant to trigger a recovery of the slave. On receiving one bulletin, the question is how long the customer takes to reach it'south fault limit?. Information technology is possible that this is being reached subsequently ane message.
picprogrammer Joined: 10 Sep 2003 Posts: 35	Posted: Tue Jul 31, 2018 five:55 am As in my beginning message, the SDA is high. Otherwise it would not pass the i2c_start. Checked with oscilloscope. After replacing cpu on both units no more than problems.
temtronic Joined: 01 Jul 2010 Posts: 8384 Location: Greensville,Ontario	Posted: Tue Jul 31, 2018 6:30 am comment. since replacing the Motion-picture show 'cured' the trouble.... I'd check the PCB for a bad solder connectedness. Look under a adept light with magazine lens. I got 'scrap' with a similar problem and had missed soldering One connectedness. The pin was making physical connection until the temp/hunid inverse. Under the right conditions the PCB shrunk but plenty to open up the circuit. It had worked for months...sigh I'v got 30 year erstwhile PICs all the same running today and then they don't 'wearable out'.... Jay
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