![]() This breakout board uses the ILD213T optoisolator and discrete transistors to correct the logic. This board will isolate the systems, creating a type of electrical noise barrier between devices. We often use this board to allow a microcontroller control servos or other motors that use a higher voltage than the TTL logic on the (3.3V or 5V) micro, and may cause electromagnetic interferance with our system as the motors turn on and off. This allows the low-voltage side to control a high voltage side. This IC has two LEDs and two photodiodes built-in. This board electrically isolates a controller from the high-power system by use of an opto-isolator IC. This board is helpful for connecting digital systems (like a 5V microcontroller) to a high-voltage or noisy system. Then try the other system.This is a board designed for opto-isolation. Look at the other pins relative to earth ground too. ![]() Try connecting the scope probe tip and only the tip to one system’s GND pin and see if there is DC there. If you don’t know for sure how the systems are grounded, you could poke around a bit with your scope and likely find out. I am not saying that your problem was absolutely a ground problem I’m just saying that your strange symptoms do fit that hypothesis. I have seen cases where the scope probe ground wire acted like a fuse and melted due to high current. This is normally a good thing for your safety but there are times when you must run a scope without a safety ground on a isolation transformer. Your scope also has a hard ground which is typically connected from the probe to earth safety ground. A no-ground situation can cause inputs to float and work at some times and not others as well. Turning off serial makes all the pins be high impedance inputs (with protection diodes) so that can possibly open a ground problem. If the GND pins on the two sides of the optoisolator are not connected together, that will work OK but your schematic does not indicate that. So in your schematics above, exactly which +5 and which GND you are using is key. Hi you are careful with the power connections for the optoisolators, then yes they will get you out of ground problems. ![]() There is a lot going on with this setup with 24v to 5v converters and other equipment so just trying to figure it all out one by one. When I plug in both devices at the same time the device on Software Serial stops receiving data while the 3.3v UART device on the RX port keeps on working. When the Software Serial device is connected by it’s self it works just fine at 19200 baud. When the 3.3v device is connected the Photon receives the data always without issues. ![]() ![]() I basically have 2 pieces of equipment one with a 3.3v UART port being read by RX pin on the Photon and another 4.5v UART port that is being read on pin D2 on the Photon using Software Serial. I have an oscilloscope out now trying to figure out what exactly is causing problems. I just picked these up at a local Fry’s because they were quick and easy to get for testing. I shouldn’t even need it but I had some issues pop up that I thought this isolation may be able to fix it but after testing level shifters and opti-isolators they are making no difference. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |