Hello,
I am using an Arduino Zero (https://docs.arduino.cc/hardware/zero) to control a dimmer circuit, that is setup using a common Source. In order to avoid damage, I am trying to isolate the ground from the USB connected to the PC. I managed to get this to work using a laptop not connected to the wall. However, when using USB isolators such as the Linear Technology LTP 2884 (https://www.analog.com/media/en/technical-documentation/user-guides/dc2092a_ltp2884fa.pdf), and the Adafruit USB Isolator (https://media.digikey.com/pdf/Data%20Sheets/Adafruit%20PDFs/2107_Web.pdf) the COM port appears for several seconds before displaying "Device Descriptor Request Failed". Is there a way to get this to work with the USB Isolators I am currently using, also I do not have access to the code but it does work without the USB isolator?
Yeah, I am trying to figure out how to keep communication between the PC and the Arduino without creating a path to ground. I was hoping to use a USB Isolator to get around this on the Desktop, since the Laptop works fine. However, there is also the worry that something might break and change GND/SRC reference.
The line connection to the Arduino Zero shown in the diagram is indeed extremely dangerous.
The Zero must be galvanically isolated from the AC circuit. The usual ways are to use an optocoupler for a logic connection, an optocoupled Solid State Relay for direct control of the AC line, etc.
What are the components attached the the Arduino Zero? They are drawn using the symbols for an N-channel and P-channel FET. However the lower component is labelled SCR, Which is it?
Also the arrangement seems to only serve to put a dead short between Live and Neutral - BANG I don't see a load you are supposed to be controlling anywhere.
It is based off of this schematic with the load connected between the second FET and Neutral, using GND/SRC as a voltage reference for the equipment. In order for the Arduino to control the FET Drivers I am trying to isolate it using a USB isolator so there is not a direct path to ground.
Let me rephrase the question I am hoping to get an answer for, I am using an Arduino Zero (https://docs.arduino.cc/hardware/zero) connected to my Desktop PC. However, when using USB isolators such as the Linear Technology LTP 2884 (https://www.analog.com/media/en/technical-documentation/user-guides/dc2092a_ltp2884fa.pdf), and the Adafruit USB Isolator (https://media.digikey.com/pdf/Data%20Sheets/Adafruit%20PDFs/2107_Web.pdf ) the COM port appears for several seconds before displaying "Device Descriptor Request Failed". Both Isolators use LOW&FULL USB Speeds, and I had contacted Arduino prior to verify that Arduino Zero would operate off of FULL Speed USB. Why does this not work using my USB isolators, and how would I go about getting my PC to communicate with the Arduino Zero through a USB isolator?
I believe I found the issue with the communication errors between the Arduino and the PC. The Arduino Zero has a programming port capable of High-Speed USB (480Mbps), the PC has a USB 3.0 (5Gbps), and the Isolator is capable of Full-Speed USB (12Mbps). Leading me to believe after a successful handshake the devices try to communicate with each other using High-Speed USB, but the Isolator prevents this from happening leading to the "Device Descriptor Failed" error. In order to get around the communication issues I can use a USB 1.1 Hub (12Mbps), or a High-Speed USB Isolator since there is currently nothing communicating with the 2 devices to force them to stay at Full-Speed USB. Attached below is a picture of the handshake between the 2 devices.
