Terminus FE1.1 USB hub board: the answer to attach 4 USB gadgets – Open Electronics

Based mostly on a single chip from Terminus, it lets you join 4 USB gadgets ranging from a micro USB port; the form-factor is designed for pairing with Raspberry Pi Zero.

Everyone knows what a USB hub is, since at the least as soon as all of us needed to take care of it at house or work to hook up with a Private Pc port with totally different gadgets, that’s, to attach extra gadgets than the variety of USB ports obtainable within the PC.

Properly, the hub is a multiplier of USB ports that enables, ranging from a channel linked to a USB host (such because the USB connection inside the pc, for instance …) to double, quadruple, and so forth, distributing, along with the bus, even the facility provide. The sorting consists of a repetition of the information channel, which is possible as a result of, in accordance with the Common Serial Bus protocol, a USB bus, consisting of the canonical two knowledge wires (D+ and D-) referred to the widespread floor with the facility provide (GND), will be approached 127 gadgets (the 128th is the Host, i.e., the Grasp unit of the bus).

Though available on the market you could find hubs of all sizes and shapes, powered or not, it appeared attention-grabbing to develop our challenge and suggest it on these pages, for at the least two causes: it’s a small board simply built-in into different digital gadgets, and furthermore, its form-factor was designed to overlap with the well-known Raspberry Pi Zero, which is linked by micro USB connector on the aspect to broaden the chances (the Raspberry Pi Zero has just one USB).

So, let’s analyze the wiring diagram of our small common hub, which helps the two.0 Excessive-Velocity model of the protocol and lets you join gadgets enabling communication between them at a pace (data-rate) of 480 Mbit / s.

The USB hub circuit

The complete hub has been realized by a single part, which is the Terminus FE1.1 built-in circuit, which internally incorporates a whole USB 2.0 Excessive-Velocity hub with 4 ports (known as “downstream”) plus one enter (or begin, in the event you favor, which is the “upstream”), all encapsulated in a 14+14 pin SSOP SMD bundle, as you see in Fig. 1 the place the pinout of the built-in circuit is proven.

Fig. 1

Our part helps particular options akin to GSMA Common Charging Resolution (UCS), which is totally compliant with USB-IF specification “Common Serial Bus rev. 2.0 and Battery Charging rev. 1.1; the machine lets you implement a 4-port low-power USB 2.0 hub.

The top quality of the FE1.1 is ensured by the built-in general system scan and self-test mode options, which will be utilized on the analogue front-end (AFE). Excessive, Full, and Low Velocity throughout construct and testing.

The FE1.1 could possibly be optionally configured to help Charging Downstream Ports mode, as outlined by the USB-IF specification; by enabling this function, the USB hub will be simply reworked right into a battery charging resolution for moveable gadgets akin to smartphones and tablets.

This established, we will go inspecting the wiring diagram, through which we will see the built-in U1 linked within the basic configuration that gives a USB connector to hook up with the Host (USB H) and 4 peripheral gadgets (USB1, USB2, USB3, USB4) which might be equal to one another, from the USBH can also be taken the facility provide for the chip and the 4 USB gadgets.

The built-in circuit has an inner 3.3V voltage regulator whose output voltage, obtainable between pin 21 and the bottom, is filtered by capacitors C1 and C6 and goes to excessive logic degree on pin OVCJ, which is the safety stage towards the extreme present draw. All of the logic contained in the built-in circuit operates at 3.3V whereas the USB knowledge aspect operates at 5V.

The operation of the entire, and specifically the information price of the USB ports, is synchronized by means of the inner oscillator that belongs to the quartz Q1; within the wiring diagram, you see solely the quartz as a result of the “load” capacitors that with it contribute to figuring out the oscillation frequency, are built-in into the FE1.1.

The pull-up resistors that you simply see within the circuit are used to set or disable some options of their pins: for instance, the one linked on pin XRSTJ units at a excessive degree the exterior reset line, which on this challenge we don’t use and subsequently we preserve it at one logic (3.3V); the road lets you reset, for instance with a button, the operation of the hub, if it will get caught, so if you wish to have a tough reset, you could join a usually open unipolar button between pin 17 and GND and you’re going to get it.

R4 units the Bus Energy Sense operation by means of the VBUSJ pin, whose standing identifies the first energy supply of the hub; in our case, the excessive degree signifies that the hub is self-powered and that the supply has sufficient energy to produce Excessive-Energy gadgets on the downstream ports aspect (that is the case of utilizing an influence provide that gives present -through a coaxial plug- to Vdd5 and GND pins).

In any other case, i.e., if pin 19 is held low, it’s assumed that energy is coming by means of the USB Host socket, and subsequently the IC limits the present of every USB downstream port to 100 mA.

R5, utilized to pin 18, manages the Upstream Port Energy (VBUS) Monitor operate, which means that the built-in unit screens the presence of energy on the USB bus on the Host aspect: a excessive degree implies that the Host is powered. Due to this fact the hub can work usually, whereas if the extent is low, it implies that on the USBH enter socket, there is no such thing as a energy, and subsequently the hub is put in a power-down state.

Within the circuit, there are additionally 4 LEDs mounted two by two antiparallelly and pushed by two particular pins which might be LED1 (pin 23) and LED2 (pin 24); the 4 LEDs have, in flip, a standard pin that’s DRV, which is switched by the inner logic to activate the diodes in multiplex mode. In observe, the management of LEDs is as follows: when you could mild LD1 and LD2 (or simply one of many two), you set the DRV line to a excessive degree and LED1 and/or LED2 to zero logic, whereas when you could mild LD3 and/or LD4, you ship the DRV to zero logic and put LED1 and/or LED2 to a excessive degree.

The primary output manages the LEDs indicating {that a} machine is linked to the downstream ports 1 and three, i.e., LD1 issues exercise on the USB1 connector and LD3 that on the USB3 connector; when at LD2, it reveals the presence of gadgets linked to USB2 (LD2) and to USB4 (LD4).

Every pair of LEDs absorbs a present restricted by the resistor that’s in sequence (R1 for D1/D3 and R2 for D2/D4), and that clearly intervenes on just one diode at a time, since, being the LEDs in antiparallel, when one leads the opposite is blocked and vice versa, the present of 1 diode at a time at all times flows within the resistor.

We proceed with the circuit evaluation by going to resistor R6, which units the bias present of the analog levels contained in the IC.

We conclude the outline of the circuit diagram with capacitors C2 and C5, positioned between pin VD18 and floor, which, like these utilized to pins VDD3 (between them and floor), are used to filter the voltage generated by the regulator at 1.8V contained in the built-in circuit.

Element Checklist:

R1, R2: 470 ohms (0805)

R3, R4, R5: 100kohm (0805)

R6: 2.7 kohm 1% (0805)

C1, C2, C3:  10µF6.3V Ceramic (0805)

C4, C5, C6, C7: 100 nF ceramic (0805)

LD1, LD2, LD3, LD4: Inexperienced LED(0805)

Q1: Quartz 12Mhz (3.2 x 2.5mm)

U1: FE1.1s

USB1, USB2, USB3, USB4: USB-A feminine connector from CS

USBH: Micro-USB connector

Numerous

– Printed circuit board S1459 (86×37 mm)

Scheme

CONCLUSIONS

The small USB hub that we have now described performs the identical duties because the USB 2.0 hubs that you could find available on the market and subsequently lets you join as much as 4 USB gadgets (for instance, printers, mice and keyboards, scanners …) in machine mode to a single USB port, which will be that of a private pc.

It additionally gives energy to the gadgets, supplied that they take up, all collectively, the utmost present drawable from the USB of the pc and bearable by the micro USB socket that’s the enter port.

To depend on the next present to the output ports must interrupt the monitor that carries the +5V from the micro USB socket to the 4 USB-A and energy the +5V line of the latter with an exterior energy provide, able to delivering all the present that the Common Serial Bus 2.0 commonplace contemplates for USB ports; the factor is completely possible, though it was not executed in our hub as a result of the circuit was not created with that goal.

The circuit can nonetheless be used as a stand-alone hub or built-in into current gear, maybe mixed with a Raspberry Pi board.

FROM OPENSTORE

Chip 1 IN – 4 OUT USB 2.0 Excessive Velocity