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Er... Paul I think there is mis-communication here? I mentioned i have 3 of the sparkfun rs485 breakout and only one is broken. All Teensy work fine with the other two. If I understand correctly Sparkfun RS485 breakout is not PJRC product right? Best Regards, Bai Shi

Most properly damaged either during manufacturing or shipping. We didn't do anything funny with it, from the first usage it's giving this problem. I'd rather believe it was stroke by ESD or a cold solder joint. Either it is a little beyond my knowledge, I even don't know how to verify =(...

Hi Paul, we have 3 of them and only 1 have this strange behavior. I'd rather believe it is damaged by ESD or cosmic ray =P. Regards, Bai Shi

Hi Steve, Do you know how to invert the data? The UART you mentioned as in the UART in Teensy3 or the RS485 breakout? I couldn't dig it out though. Actually my finding seems that the space and mark are identical to a brand new RS485 breakout. Just that the idle is different. It might not be...

No it didn't really work. The RS485 breakout pulls to ground when it is idle. Even if i put a 120Ohm pull up it barely manage to pull up to 1.x V on idle. I think the RS485 breakout is beyond repair if I'm not wrong.

Hi Paul, Here is the update. It seems the problematic rs485 breakout's power level for idling is 0v instead of 3.3v. Thus it confused Teensy hardware serial. Though I'm not sure why Serial2 and Serial3 seems pretty happy with this. I think it doesn't worth much effort to cater for the...

Hi Paul, Just give me two days. It is local holiday here and there is 10+ hours time difference. There is some weirdness in one of the 485-232 converter, but I still don't know what indeed it is. Will update you once i get touch to it. Regards, Bai Shi

Hi Paul, Our further investigation shows that seems that Serial1 of Teensy hardware serial have some compatibility problem with this sparkfun transceiver. We tested on 3 Teensy 3.0 and 1 stopped half way, 2 continue to receive data from serial. We tested on 3 Teensy 3.1, all of them stopped...

Attached waveform on Pin0. It looks working fine all the way. I tweaked the delay between chunks and found that 0.1 second will not cause problem of the serial, but 0.2 second sleep will make it sleep forever. Regards, Bai Shi

Thanks HWGuy, we are using same wiring except that we use 3.3V instead of 5V. The breakout looks working fine. Best Regards, Bai Shi

Hi Paul, I checked with my colleague the RTS pin is connected to Teensy and is pulled to Digital 0 by Teensy output. So this should not be the cause of missing data. Yes the program keeps transmitting chunks of data with a 2 sec interval. No matter what the data is, when the transceiver...

Thanks Pete, but it is a layout problem of the forum post, maybe i shall use code block instead of pre block. Anyway if there is a space at that position, the program will fail with unexpected character before even able to run. Regards, Bai Shi

Hi Paul, I assume we have connected RTS pin to GND otherwise it shouldn't receive the initial few bytes, should it? Do you assume that if RTS is floating it may cause intermittent problem of receiving? But I don't think it should be the case as each time I re-upload Teensy program it will allow...

Hi Paul, I'm experiencing a very very strange problem on one of the Teensy 3.0. My project has progressed a bit but recently found strange behavior on received bytes from Serial1. We often receive partial data and couldn't identify the source. We initially thought i was cabling issue, but every...

Hi Chris, My use case is using Linux all the way with Makefile and teensy loader. So it has almost zero chance for a conflict Serial access to happen (such as Serial Monitor). However it still happens. After adding resistor for the MOSFET pin it didn't burn another chip so far since my last...

Hi Paul, Thank you for the detailed reply. I believe the only portion could go wrong is the MOSFET. I will add resistor to it as switching time for me is totally not important. I only use it to switch the other ARM board on and off at most once a day. I'm a little lost on the 3.9V on MOSFET's...

Hi David, Just curious, because I had similar problem before, do you use things like #pragma pack inside your program? I used to have one pack 1 while the others not packed, and I have very similar problem, though the number is much larger, around 0xffffff80 to 0xffffffff. I tried to apply...

Hi Paul, Sorry for the late reply. Wife just delivered and spent all my time at hospital. Yes I claim myself did everything correctly, otherwise I don't believe the Teensy would working for around 2 weeks before failure and we have quite a few Arduino chips running around for several months...

I don't think a schematic is much useful here. Our use case is soooo simple, it only drives MOSFET Gate to ground. That's it. The input comes from another Arm7 chip and it could never be anything higher than 3.3V. I understand your eager to understand the situation, but we are not trying to...

Hi scswift, No I didn't put any resistor between teensy's pin and MOSFET and the MOSFET itself is a quite powerful one. This is the one I'm using https://www.sparkfun.com/products/10349. There is a 1K resistor between pull up and 3.3V and using Teensy as sink to draw the voltage of MOSFET gate...

Hi Robin, We have purchased a few Teensy 3.0 to use as a power control / watchdog to our system. We made two sets of prototype and put them in sealed enclosuers. The maximum air temperature logged was 76C / 168F and the teensy failed to boot up after power cycle. The failed chip while powered...