![]() If you still having issues with the circuit, please let me know, I will try to help. However, if said experimenter is not feeling comfortable operating tweezers inside powered circuit, a safer arrangement is shown on the title picture.ĭisconnecting peripheral, either directly or by driving PIN pin, with power applied to the isolator and host side connected, will most likely solve device detection problem. An experimenter with good eyesight and steady hand can easily connect those two points with tweezers. The closest ground point is right pad of bypass capacitor, which sits above R8. Left side of it, the one right below the “1M” mark is connected to PIN pin (12). This resistor is located next to peripheral side USB connector and marked 1M above it. Normally it is held at 5V by R8 pull up resistor. It is possible to simulate device disconnect without breaking actual connection by pulling PIN pin of ADuM4160 to ground. I tested about 50 different USB devices and found out that while breaking the connection on the peripheral side works every time, host side disconnect does or does not help depending on device. However, when host and peripheral are talking through ADuM4160, this is not always the case. If we are dealing with typical copper-wire-connected USB host and peripheral, which end of USB cable gets disconnected and reconnected would not matter. To get attention from the host, we need to generate bus event, i.e., disconnect the peripheral and connect it back again. If device is not answering (like for example, when self-powered device is turned off), host will give up and post “Device not recognized” message. When device is enumerated, application takes over. If device is answering, host keeps querying the device and eventually enumerates it. Host sees it, sends bus reset and tries to query the device. USB device, when connected, pulls one of bus lines up, often times also with a resistor connected to Vbus and data line. When nothing is connected to USB port, the bus is held at ground level with pull down resistors on the host side. Here I will try to explain what is happening and also share my ideas how to troubleshoot and possibly fix the problem. While setups described in those e-mails were different, the problem was the same – a PC refusing to recognize the device connected through the isolator. I decided to write this article after receiving several e-mails from people who bought my isolator. ![]() I am getting “USB device not recognized” error message – what do I do? Also, since the isolator is soldered into my circuit, “reconnect peripheral” suggestion seems too difficult to follow. ![]() Best of all, this USB isolator even has its own isolated 5V power supply that can supply 100mA, making it perfect for your BitScope Micro USB! Protect your computer or laptop, use one of these in between your ports.ADuM4160 PIN pin grounding Q. It is particularly useful when paired with USB testing instruments, you need to separate or isolate your eath ground (thru the USB connector to the computer to the power plug) from your circuit for high voltage, accident-protection, or floating ground needs. Not for high speed USB devices, often used for video cameras (check your product to make sure its low/full compatible) Based on Analog Device's USB isolators Works with any 1.5Mbps (low speed) or 12Mbps (full speed) USB device. This handy little low-cost USB isolator is exactly what you need to provide protection against harmful noise, ground loops, surges, and spikes. Have some USB logic analyzer, multimeter or oscilloscope and bumping up against the frustation of a shared earth ground? The Offspring (known for being electrical engineers) wisely sang "Ya gotta keep'em isolated!" Power and signal isolation improves common-mode voltage, enhances noise rejection, and permits two circuits to operate at different voltage levels. ![]()
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