# Tag Info

## Hot answers tagged usb

6

From the datasheet: Breakdown voltage, IO to GND is the critical parameter. Some parts may conduct at 4.5V, shorting the 5V VBUS to ground and other may not. This is not a suitable part for VBUS ESD protection.

3

a more USB-specific question -- is it absolutely necessary I use a mux "designed for USB 3.x" (per product branding) ? Or can I use traditional differential multiplexers? what attributes of these multiplexers make them better for USB 3.x SuperSpeed mux anyway? The Power Delivery uses transmission rate of 300 kbps. At this low rate almost any MUX will ...

3

I don't know who designed that board, but it has several questionable connections. First, CH340C chip datasheet requires V3 pin connected to VCC if VCC is 3.3V. On the board it is permanently connected to decoupling capacitor, which corresponds to 5V configuration. On the other hand, the LEDs are connected to 3.3V supply, so they will (maybe) operate in ...

2

Your understanding is correct. USB packets go both ways, so SYNC, PID, DATA, CRC, and EOP are formed by whoever sends the particular packet. And yes, a device (at HS rate of signaling) must respond in 192 bit times (400 ns) to standard requests. [the host, however, will wait 1700ns before declaring time-out, to accommodate for other propagation delays along ...

2

Several potential issues exist that I can see. Firstly, your "decoupling caps" should be as close to the pins they are inteded to decouple (usually the IC power pins). This can cause all sorts of weird behaviour in digital circuits. Your D+/D- diff pair is not routed with constant spacing, which could cause signal integrity problems due to impedance ...

2

You will be connecting all devices in parallel, so the voltage requirement stays constant at 5V. To get the needed current just sum up all device input currents. If you have 4 devices with 2A each you need 8A. The power is V*I, in this case 40W. If you want to power the devices from battery for a longer time, you obviously also have to keep in mind the ...

1

You cannot ever get to the "rated speed" on any peripheral link because the rates are usually expressed in raw bits per second, and every link has packet framing, encoding overheads, and protocol overheads on every level on connection stack. So the "1.5 MB/s" is not possible to achieve even in theory. The internet-quoted transfer rates (800 kB/s WRITE and ...

1

If you really need High Speed, your best bet is likely to be two EZ-USB FX2, each handling one port, and one of the chips being able to send the other into suspend mode (or a proper protocol with gracious shutdown instead of generating a surprise eject event).

1

You will need a mux to switch between the two data lanes. You could, for example, use an FSUSB42 with the respective $V_\mathrm{BUS}$ for the Sel line. Power switching may be a little trickier, but hard to say without knowing what you have downstream from the USB ports. Bear in mind, this will cause problems when the user plugs in the "master" USB while ...

1

Short answer, no you can't use random headphone wiring you don't know anything about for USB 2.0 signaling. It requires a twisted pair with specific impedance for differential signaling and thick enough wires for supplying the rated amount of current without too much losses. Get a USB extension cable.

1

There is no "filtering" on your usb port. On my STM32F's I usually use 22 ohm resistors like they do on the dev boards. It cleans up the eye diagram of the USB. As far as the rest of the design, it's probably not very noise proof. If you are having problems with random dropouts then the design is probably susceptible to external noise corrupting packs from ...

1

Using a relay as Michael Jennings suggests is a good solution. If you want the easiest possible solution then a premade relay module which are available on Amazon [ Many examples here ] and various Asian sites would be a good choice. A more DIY electronic solution is to use a transistor as a switch. I've shown a MOSFET here but an NPN transistor could ...

1

You could use a 5V relay module like this one. Your design will have the following connections: DC+ to USB 5V DC- to USB 0V IN1 to USB 5V NO to your raspberry pi 5V in COM to the 5V raspberry pi wall wort/plug socket power supply NC disconnected N.b The wall wort power supply's ground also needs connected to the raspberry pi. This can be connected directly ...

1

EN is enable... Or nrst pin. IO0 is a boot mode pin. When the esp32 chip exits reset, it samples io0 and if it's low it will enter programming mode. This enables the dev board to reset the board and automatically select the correct values for those pins when programming. See: https://github.com/espressif/esptool/wiki/ESP32-Boot-Mode-Selection

Only top voted, non community-wiki answers of a minimum length are eligible