Scheme for assembling an OTG flash drive from a regular USB, wiring and secrets of pinouting an OTG cable. OTG hub with additional
Everyone knows that any electronic device can be connected to a computer using a standard USB cable. Thus, using a laptop or personal computer, you can communicate with each other various devices, such as printers, cameras, smartphones and data storage devices (flash drives and external hard drives).
What is OTG?
Is there a way to do without a computer? Quite simply, a lot of adapters under the general name OTG cable have appeared on the market for a long time. Their cost varies from a few dollars to a dozen or even two. However, their difference from simple data cables is so insignificant that you can easily make an OTG cable with your own hands. For example, from the remains of old ones and adapters.
So, first we need to decide why we need an OTG cable. Powering another device using a battery may be necessary when there is no power supply nearby, for example, when traveling or hiking, but this option is not the most effective. We need to decide right away whether we will connect the two specific devices and constantly between each other, or is it better to make a universal OTG cable with your own hands for using any USB devices, like a store-bought one. It is also better to immediately check whether your device is capable of supporting such connections.
Tools and Safety
To work with cables you will need:
knife for stripping insulation;
wire cutters or side cutters (remember the saying: “measure twice - cut once”), excess soldering on the cable will worsen the quality of communication between devices and increase the resistance in general, which will affect data loss or the inability to charge due to conductor resistance;
soldering iron, solder and flux; at the end of the article we will look at how you can do without this device.
When working with a soldering iron, remember safety precautions. This device is dangerous due to its high temperature not only during operation, but also for several minutes after switching off. Protect work surface table from contact with molten tin or rosin. Protect exposed skin from touching hot parts of the soldering iron.
What is what?
First, it’s worth figuring out which contacts in plugs and sockets are needed for what, since the mini- and micro-variants have 1 more pin than the universal serial bus connectors. So, the first pin is usually marked with red insulation inside the wire and is intended for supplying voltage. The second and third pins, marked with white and green insulation, are intended for data transmission. The fourth black pin is zero or ground, working in tandem with the first supply wire. In mini- and micro-USB, such functions are assigned to the fifth and last pin, and the fourth is a marking or identifier. It is designed to provide connection information to the device and is not connected anywhere in the data cables at all.
The simplest option
First of all, let's consider the option of connecting two specific devices, for example tablet computer and a camera. Since they both have 5-pin sockets, either micro or mini USB, you just need to carefully solder the corresponding wires together. 2 scrap data cables with matching plugs will do. You need to cut them and strip the wires of insulation, and then connect them according to color differentiation, that is, black to black, yellow to yellow, and so on. Each connection must be isolated from the others using hot glue or at least electrical tape. When you connect such a cable to devices, a dialog menu will appear on the screens where you will need to select which device will be the main one in this mini-network. You can forcefully designate the main and secondary devices in the cable itself. To do this, you need to connect the 4th and 5th contacts in the main device plug, and simply do not connect the 4th contact to any other plug. Thus, the device will automatically identify itself as the main one in the connection, since the marker contact will indicate the presence of a connection, whereas on the second device it will be “empty”.
For a variety of devices
Let's consider the option of how to make a universal OTG cable with your own hands. In addition to a micro- or mini-USB plug, depending on the device, we will need a USB connector. You can take it from the old ones motherboards, cut off the USB extension cable or disassemble the USB splitter (the so-called USB hub). The latter option is preferable, as it will allow you to connect several peripheral devices to the main device at once, just like to a computer. The connection sequence is the same as above; on the device plug, the main device is similarly forcibly indicated by connecting the 4th and 5th pins. The pictures clearly show the connection diagram of pins in connectors and plugs.
With power connection
Some devices are characterized by increased energy consumption, which leads to rapid discharge of the battery of the main gadget, be it a smartphone or tablet. In this case, you can improve the OTG cable with your own hands by adding a power cable with a USB plug for network adapter. To do this, you can use the remains of a data cable from which a micro- or mini-USB plug was previously cut off. The connection is made via two current-carrying contacts, black and red, ignoring the data wires. It must be remembered that over long distances, the resistance of the wire, increased by solder joints, will reduce the voltage and current, so the use of long sections of cable will most likely not achieve a stable connection between the devices. Use approximately 20-30 cm of cable for each plug and connector to avoid breaks and interruptions in the connection.
Finally, I would like to mention how to assemble an OTG cable with your own hands without a soldering iron. The assembly principle is the same as described above, but the wire connections are made in slightly different ways. Let us point out two of them here:
Solder paste contains powdered solder and flux and does not require the use of a soldering iron. This paste is applied to the parts to be joined and heated with a regular lighter.
There are connections without the use of high temperatures at all. The so-called adhesive locks are connectors for low-current systems with a special contact that cuts into the wires using a clamping device, for example, pliers.
Whatever you decide to do yourself, remember that cutting cables is not a warranty case and such cables cannot be replaced.
The story is about how difficult it turned out to be to connect a 4g modem, flash drives and a mouse to the tablet, and even prevent it from running out of power. Disassembly, voltage tests, Orico cable, the item is good, I recommend it, not item 18. Everything is under cut)
Hello! Today we are reviewing a mcroUSB-OTG hub with additional power. There was already a review of it on Muska, but it was very brief, I’ll try to add more. It all started when I gave my parents a Prestigio Visconte Quad (8" tablet) Intel Atom Z3735G, 1GB RAM, 16GB ROM, Windows 8.1\10). What was needed was a Windows tablet so that the owners could use it as comfortably as on their laptop in general. I bought the tablet from a friend, so the equipment was far from original: some kind of frivolous 1A charger and the first microUSB cable that came to hand. As a result, during active use (wi-fi, online video, bluetooth mouse), the tablet was discharged while charging. Moreover, the 4g modem connected via an otg cable did not start; it appeared in the system, then fell off again at the stage of installing the firewood. Thanks to the community on 4pda, I found out that the modem simply does not have enough current. And a whole book is devoted to the problem of surviving with one microUSB. And I started making cables with additional power according to 4pda diagrams.
Scheme using scotch locks
Option with hub
Everything worked, the modem started up, but using such cables was inconvenient, and the design itself did not last long. It was decided to kill all birds with one stone and purchase a factory version and the choice fell on Acasis H-027. I immediately liked its strict design and the modest but original Acasis marking, which looks as if it had Asus written on it, I would not have doubted it at all. I chose the cheapest lot at that time and received it 37 days later. There were no instructions included (although some people do). All packaging is bubble wrap and a bag.
The device can operate in three modes:
1. Charging only
2. otg+charging
3. OTG only
There is a switch to switch between them.
On my tablet these modes worked like this: 1. otg+charging
2. otg+charging
3. OTG only
The body of the device consists of two halves, fastened using the tongue-and-groove method. When disassembled, the spikes suffer and heroically fall off. Everything inside is clean and tidy.
The hub is controlled by a fe 1.1s microcircuit, very cheap, it can be found in many USB 2.0 hubs from Ali, from very good models to copies that literally fall apart in your hands. Often found in inexpensive Chinese tablets.
The indicator light indicates that power is connected. It's not very well implemented - just a hole in the body.
The Otg mode works flawlessly, I didn’t measure copying speeds from drives, everything is normal there. “OTG+charging” mode with Orico colorful 0.5m cable
with three flash drives
with screw and flash drives
With the 4g modem, everything is also correct. Basically, to power the tablet and hub, I use a Robiton charger and an Orico microUSB cable 2 m long.
In the maximum possible option: charger + 2 meters of cable + hub with screw, modem and mouse, the tablet charges slowly, but it charges, otg works, i.e. The hub is fulfilling its purpose. Nevertheless, we will take measurements.
without hub with 1A load
with hub and 1A load
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Not all old tablets support the function of connecting a flash drive or modem, but I will tell you how to outsmart them and connect a flash drive, modem, and even HDD.
Today I would like to present to your attention an OTG adapter.
First, I want to tell you what OTG is? This is a way to connect to your tablet or phone that supports the OTG function, printer, flash drive and even hard drive. This connection is also called USB-host.
You can also connect a keyboard or mouse to your gadget, if the gadget supports such a function.
And so, to create this miracle cable, we need:
Old USB extension cable
Micro USB connector (you can get it from a regular USB cable for your device)
Soldering iron and soldering accessories
And so, let's go, to make such a cable, we will need to connect the 4th pin to the 5th pin of the micro USB connector
We must get to the fourth pin and connect it with a jumper to the GND wire as shown in the picture
After we connect the 4th and 5th contacts with a jumper, our gadget will perform the function of an active device and will understand that another passive device is about to be connected to it. Until we install a jumper, the gadget will continue to act as a passive device and will not see your flash drives.
But that’s not all; to connect a hard drive to a phone or tablet, this adapter will not be enough for us. To connect devices whose consumption is more than 100mA, namely 100mA can be supplied by the port of your device, we will need to connect additional power to our OTG cable, which should be enough for your hard drive to work.
Here is a diagram of such an adapter
Now it's time to start collecting
We take an old USB extension cable and cut it not too far from the 2.0 connector, since the current is only 100mA, to avoid large losses. Cut approximately in the same place as shown in the photo
Afterwards we clean our wire
I connected pins 4 and 5 with a drop of solder.
Well, here is our entire cable assembled
All that remains is to check the functionality, take the tablet, insert the “adapter” and insert the flash drive into it, everything works, as the flashing LED on the flash drive and the tablet detecting the flash drive tell us.
I talked about choosing a tablet, and in particular about the function I needed, such as the ability to connect various USB devices to it, such as flash drives, a card reader (and, accordingly, memory cards of different formats), etc.
So, having bought a MoveO tablet! TPC-7HG I suddenly encountered a problem that was completely unexpected for me. The point is that of this tablet There is only a mini-USB connector. In itself, this was not a surprise or a problem for me - on the contrary, it is easier to find a standard mini-USB cable in order to replace, for example, a faulty charging cable if necessary. An unpleasant surprise for me was that in my town nowhere - NOWHERE! - the mini-USB OTG cable was not sold! It didn't come with the kit either. Having gone to all possible and impossible stores, I came to the conclusion that, perhaps, it would be easier and faster to make such a cable with my own hands.
ATTENTION!!! EVERYTHING YOU DO IS AT YOUR OWN RISK!!!
And now a little theory. You cannot simply take and solder together a mini-USB plug with a piece of wire from one cable and a so-called USB-female plug from another cable. No, that is, of course, you can solder it, but just connecting it to the tablet and making it work with this cable will not work for any device. Here's the thing.
A standard mini-USB cable has a five-pin plug:
001.
The contacts in it are numbered as follows:
002.
But a standard USB cable only has 4 wires. Where did the fifth wire go? Nowhere. It simply does not solder to the connector ends!
The purpose and color marking of the wires in a regular USB cable are as follows:
1 - Red VBUS (+5V) +5 Volts DC voltage relative to GND. Maximum current - 500 mA.
2 - White D- (-Data)
3 - Green D+ (+Data)
4 - Black GND - common wire, ground, minus, 0 Volt
The main difference between USB OTG cable consists of a plug. In a mini-USB OTG cable (as well as in a micro-USB OTG cable), pins 4 and 5 are closed to each other. In a regular (non-OTG) data cable, there is no wire soldered to the 4th pin of the plug. This plug is called USB-BM mini (micro). If you solder pins 4 and 5 together, then such a plug will be called USB-AM mini (micro). It is by the presence of a jumper between pins 4 and 5 in the USB-AM micro plug that the tablet determines what they are going to connect to it peripheral device. If this jumper is not present, then it itself will act as a passive device and will not respond to the connection of any kind of USB devices to it.
So, we have become familiar with the theory - let's start practicing.
We take a regular mini-USB cable and carefully open its connector with a utility knife. As a result, we get the following set of young technicians:
003.
Next we need to connect the 4th and 5th pins of the plug. This can be done, for example, by carefully cleaning the sealing plastic from the back of the connector. But here two unpleasant surprises await. Firstly, it turns out that this is not so easy to do without damaging anything, because the contact group is filled in conscientiously - you just have to pick it out. The second “surprise” is a short contact of the 4th contact (forgive me my pun!), which makes it extremely inconvenient to solder something to it:
004.
Having honestly ruined the first cable, I take up the second one, but I deal with it a little differently. Having opened and disassembled the mini-USB connector, from the back side of the contact pad, using the same stationery knife, I carefully scrape off the plastic in the area of the 4th and 5th contacts, right down to the contacts themselves:
005.
Now take a soldering iron and place a neat jumper between these two contacts with tin.
006.
The only thing you need to watch out for here is to keep the contact pad as flat as possible, both on this side - since in this case our connector may simply not fit back into its metal case, and from the opposite side (that is, from the contact side itself) - since unevenness there can lead to bending contact group tablet sockets, and this is already fraught. After making the jumper, you need to take care to avoid short circuiting the freshly soldered contacts with the connector body. To do this, I used such an indispensable tool as Poxipol.
007.
Please note that only TRANSPARENT Poxipol has electrical insulating properties. Metal Poxipol has quite conductive characteristics and, naturally, cannot be used in this case.
After Poxipol has hardened, the excess can be cleaned off with a knife and the USB connector can be assembled:
008.
In principle, it would be a good idea to fill it with Poxipol on top, but I recommend doing this after the cable has been tested for functionality.
And cut off the USB-female connector with a piece of wire from it:
010.
Now we only need to connect the two resulting cables (one with a mini-USB connector, the second with a USB-female connector) to each other.
First, we “dress” one of the wires with heat shrink:
011.
Take the soldering iron again:
012.
And we carefully solder (from the word “solder” and not “solder”!) the wires in the cables.
013.
To isolate the wires from each other, I used the same Poxipol. And when it froze, I covered it all together with heat shrink:
014.
The result is a cable like this.
