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Hot and cold connection of devices. HDMI interface burnout due to hot connection

In order for any residential building to function normally, it is necessary to install a water supply system. Its proper design will ensure timely supply and sufficient water pressure. This article will discuss in detail the hot water supply scheme, types of connection and its features in an apartment building.

What is special about the water supply of an apartment building?

It is very difficult to provide water to a building with a large number of storeys. After all, the house consists of many apartments with separate bathrooms and plumbing fixtures. In other words, water supply schemes in apartment buildings are a kind of complex with separate pipe distributions, pressure regulators, filters and metering equipment.

Most often, residents of high-rise buildings use water from the central water supply. With the help of a water supply, it is supplied to individual plumbing fixtures under a certain pressure. Often water is purified using chlorination.

Composition of the central water supply system

Centralized water supply schemes in multi-storey buildings consist of a distribution network, water intake structures and treatment plants. Before getting into the apartment, water travels a long way from the pumping station to the reservoir. Only after purification and disinfection is water sent to the distribution network. With the help of the latter, water is supplied to appliances and equipment. Pipes for the central hot water supply circuit of a multi-storey building can be made of copper, metal-plastic and steel.

The latter type of material is practically not used in modern buildings.

Types of water supply schemes

There are three types of water supply system:

collector;
sequential;
combined (mixed).

Recently, when it is becoming more common in apartments a large number of plumbing equipment, use collector wiring diagram . She happens to be the best option normal functioning of all devices. The collector-type hot water supply scheme eliminates pressure drops at different connection points. This is the main advantage of this system.

If we consider the diagram in more detail, we can conclude that there will be no problems with using the plumbing equipment for its intended purpose at the same time. The essence of the connection is that each individual water consumer is connected to the cold and hot water supply riser collectors separately. The pipes do not have many branches, so the likelihood of leakage is very low. Such water supply schemes in multi-storey buildings are easy to maintain, but the cost of the equipment is quite high.

According to experts, the collector hot water supply system requires the installation of a more complex installation of plumbing fixtures. However, these negative aspects are not so critical, especially considering the fact that the collector circuit has many advantages, for example, hidden installation of pipes and taking into account the individual characteristics of the equipment.

Sequential hot water supply circuit multi-storey building - this is the easiest way to wire. This system is time-tested; it was put into operation during the Soviet era. The essence of its device is that the cold and hot water supply pipelines are parallel to each other. Engineers advise using this system in apartments with one bathroom and no big amount plumbing equipment.

Popularly, such a hot water supply scheme for a multi-storey building is called a tee scheme. That is, from the main highways there are branches that are connected to each other by tees. Despite the ease of installation and savings consumables, this scheme has several main disadvantages:

In the event of a leak, it is difficult to look for damaged areas.
Inability to supply water to a separate plumbing fixture.
Difficulty in accessing pipes in case of breakdown.

Hot water supply for an apartment building. Scheme

Pipe connections are divided into two types: to the hot and cold water supply riser. Briefly they are called cold water and hot water. The hot water supply system of an apartment building deserves special attention. The DHW network diagram consists of two types of wiring - lower and upper. To maintain high temperatures in the pipeline, looped wiring is often used. The gravitational pressure forces the water to circulate in the ring, despite the absence of water intake. In the riser it cools and enters the heater. Water with a higher temperature is supplied to the pipes. This is how continuous circulation of the coolant occurs.

Dead-end highways are also not uncommon, but most often they can be found in utility rooms of industrial facilities and in small residential buildings with low storeys. If water selection is planned intermittently, then a circulation pipeline is used. Engineers advise using hot water supply in apartment buildings (the diagram was discussed above) with a number of floors of no more than 4. A pipeline with a dead-end riser is also found in dormitories, sanatoriums and hotels. Dead-end network pipes have a lower metal consumption and therefore cool faster.

DHW networks include a horizontal main pipeline and distribution risers. The latter provide pipe distribution along separate object- apartments. DHW is installed as close as possible to plumbing equipment.

For buildings with a large length of main pipes, schemes with circulation and looped supply pipelines are used. A prerequisite is the installation of a pump to maintain circulation and constant water exchange.

Two-pipe DHW circuit - Photo 07

Modern builders and engineers are increasingly resorting to the use of two-pipe hot water systems. The principle of operation is that the pump takes water from the return line and supplies it to the heater. This pipeline has a higher metal consumption and is considered the most reliable for consumers.

There are two different ways to think about hot plugging. The kernel views hotplug as an interaction between the hardware, the kernel, and the kernel driver. Users view hotplug as an interaction between the kernel and userspace through a program called /sbin/hotplug. This program is called by the kernel when it wants to notify user space that some type of hotplug event has just occurred in the kernel.

Dynamic devices

The most common use of the term "hot plugging" occurs when discussing the fact that most all computer systems can now handle devices that appear or disappear while the system is turned on. This is very different from computer systems just a few years ago, when programmers knew they only had to scan all devices at boot time and never had to worry about their devices disappearing when the power was turned off for the entire machine. Now, with the advent of USB, CardBus PCMCIA, IEEE1394, and PCI hot-plug controllers, the Linux kernel needs to be able to operate reliably no matter what hardware is added or removed from the system. This places an additional burden on the device driver author, as they must now always work with a device that is suddenly taken out of service without prior notice.

Each bus type handles device loss differently. For example, when a PCI, CardBus, or PCMCIA device is removed from the system, it usually occurs before the driver has been notified of this action through its remove function. Before this happens, all reads from the PCI bus return all bits set. This means that drivers need to always check the value of the data they read from the PCI bus and be able to properly handle the value 0xff .

An example of this can be seen in the drivers/usb/host/ehci-hcd.c driver, which is PCI driver for USB 2.0 (High-Speed) controller board. He has following code in its main handshaking loop to detect that the controller board has been removed from the system:

result = readl(ptr);

if (result == ~(u32)0) /* card deleted */

Return -ENODEV;

For USB drivers, when the device connected to USB driver removed from the system, all pending urbs that were sent to the device first fail with the error -ENODEV . The driver must recognize this error and properly clean up any pending I/O if it exists.

Hot plug devices are not limited to just traditional devices such as mouse, keyboards and network cards. There are many systems that now support removing and adding entire processors and memory cards. Fortunately, the Linux kernel handles adding and removing such basic "system" devices properly, so individual device drivers don't have to worry about these things.

/sbin/hotplug utility

As mentioned earlier in this chapter, when a device is added or removed from the system, a "hotplug event" is generated. This means that the kernel calls the userspace program /sbin/hotplug. This program is usually very small bash script, which simply passes execution to a list of other programs that are in the /etc/hotplug.d/ directory tree. For most Linux distributions this script looks like this:

DIR="/etc/hotplug.d"

for I in "$(DIR)/$1/"*.hotplug "$(DIR)/"default/*.hotplug ; do

If [ -f $I ]; then

Test -x $I && $I $1 ;

done

exit 1

In other words, the script looks for all programs with the .hotplug suffix that might be interested in this event and calls them by passing them a number of different environment variables that have been set by the kernel. More detailed information How the /sbin/hotplug script works can be found in the program comments and on the hotplug(8) man page.

As mentioned earlier, /sbin/hotplug is called when a kobject is created or destroyed. The hotplug program is called with one argument command line, representing the name for this event. The main kernel and a specific subsystem are also involved in setting a set of environment variables (see below) with information about what just happened. These variables are used in hotplug programs to determine what just happened in the kernel and whether there is some special action that should take place.

The command line argument passed to /sbin/hotplug is the name associated with this hotplug event, as determined by the kset assigned to the kobject. This name can be set by calling the name function, which is part of the kset's hotplug_ops structure described earlier in this chapter; if this function is missing or has never been called, the name of the kset itself is used.

The default environment variables that are always set for the /sbin/hotplug program are:

ACTION

The line add (add) or remove (delete), depending on whether this object just created or destroyed.

DEVPATH

Directory path in file system sysfs, which points to a kobject that is currently either created or destroyed. Note that the sysfs mount point is not added to this path, so it is left to the user space program to determine it.

SEQNUM

The sequence number for this hotplug event. The sequence number is a 64-bit number that increases with each hotplug event generated. This allows user space to sort hotplug events in the order in which the kernel generates them, since it is possible for user space programs to operate out of order.

SUBSYSTEM

The same string passed as a command line argument as described above.

A number of different bus subsystems for calling /sbin/hotplug add their own environment variables when a device associated with the bus has been added or removed from the system. They do this in their hotplug callback, specified in the struct kset_hotplug_ops assigned to that bus (as described in the Hotplug Operations section). This allows user space to be able to automatic download necessary modules that may be needed to control the device that has been detected on the bus. Here is the list different types buses and the environment variables they add to the /sbin/hotplug call.

IEEE1394 (FireWire)

All devices on the IEEE1394 bus, also known as FireWire, have a name parameter for /sbin/hotplug and the SUBSYSTEM environment variable is set to ieee1394 . The IEEE1394 subsystem also always adds the following four environment variables:

VENDOR_ID

The 24-bit vendor identifier for the IEEE1394 device.

MODEL_ID

The 24-bit model identifier for the IEEE1394 device.

GUID

The 64-bit GUID for this device.

SPECIFIER_ID

A 24-bit value that identifies the owner of the protocol specification for this device

VERSION

A value that identifies the version of the protocol specification for this device.

Net

All network devices generate a hotplug message when a device is registered or unregistered with the kernel. The call to /sbin/hotplug has a name parameter and the SUBSYSTEM environment variable is set to net and only adds the following environment variable:

INTERFACE

The name of the interface that was registered or unregistered from the kernel. Examples of this are lo and eth0.

PCI

Any devices on PCI bus have a name parameter and the SUBSYSTEM environment variable is set to pci . The PCI subsystem also always adds the following four environment variables:

PCI_CLASS

The PCI class number for this device, in hexadecimal.

PCI_ID

The vendor and PCI device IDs for this device, in hexadecimal, concatenated in the format vendor:device .

PCI_SUBSYS_ID

Vendor and PCI subsystem identifiers, combined in the format subsys_vendor:subsys_device.

PCI_SLOT_NAME

The "name" of the PCI slot, which is given to the device by the kernel in the format domain:bus:slot:function . An example would be 0000:00:0d.0 .

Enter

For all input devices (mouse, keyboards, joysticks, and so on), a hotplug message is generated when a device is added and removed from the kernel. The /sbin/hotplug option and the SUBSYSTEM environment variable are set to input . The input subsystem also always adds the following environment variables:

PRODUCT

A multi-valued string listing values in hexadecimal, without leading zeros, in the format bustype:vendor:product:version.

The following environment variables may be present if the device supports them:

NAME

The name of the input device, as defined by the device.

PHYS

The physical device address that the input subsystem gave to this device. It must be stable, depending on the location of the bus on which the device was connected.

They all come from the input device handle and are set to the appropriate values if the input device supports it.

USB

Any devices on the USB bus have a name parameter and the SUBSYSTEM environment variable is set to usb . The USB subsystem also always adds the following environment variables:

PRODUCT

String in the format idVendor/idProduct/bcdDevice

TYPE

String in format bDeviceClass/bDeviceSubClass/bDeviceProtocol, which determines these dependent USB devices fields.

If the bDeviceClass field is set to 0, the following environment variable is also set:

INTERFACE

String in format bInterfaceClass/bInterfaceSubClass/bInterfaceProtocol, which defines these USB device-dependent fields.

If the kernel build option CONFIG_USB_DEVICEFS is selected, which selects that the usbfs filesystem will be built in the kernel, the following environment variable is also set:

DEVICE

A string that shows where the device is located in the usbfs file system. This string has the format /proc/bus/usb/USB_BUS_NUMBER/ SB_DEVICE_NUMBER, in which USB_BUS_NUMBER is the three-digit number of the USB bus to which the device is connected, and USB_DEVICE_NUMBER is the three-digit number that was assigned by the kernel to this USB device.

SCSI

All SCSI devices generate a hotplug event when a SCSI device is created or removed from the kernel. The /sbin/hotplug call has a name parameter and the SUBSYSTEM environment variable set to scsi for each SCSI device that is added or removed from the system. No additional environment variables are added by the SCSI system, but it is mentioned here because there is a special SCSI script in user space that can determine what SCSI drivers (floppy drive, tape drive, regular, etc.) should be loaded for a specified device SCSI.

Laptop docking stations

If a Plug-and-Play capable laptop docking station is added to or removed from a running Linux systems(by plugging the laptop into the station, or removing it), a hot plug event is created. The /sbin/hotplug call has a name parameter and the SUBSYSTEM environment variable is set to dock . No other environment variables are set.

S/390 and zSeries

On the S/390 architecture, the channel bus architecture supports a wide range of hardware, each of which generates /sbin/hotplug events when they are added to or removed from virtual system Linux. All of these devices have a name parameter for /sbin/hotplug and the SUBSYSTEM environment variable is set to dasd . No other environment variables are set.

Using /sbin/hotplug

Now that the Linux kernel calls /sbin/hotplug for every device that is added or removed from the kernel, a number of very useful tools have been created in user space to take advantage of this. Two of the most popular tools are Linux scripts hotplug and udev.

Linux Hotplug Scripts

Hot scripts Linux connections started as the very first user of the /sbin/hotplug call. These scripts look at the various environment variables that the kernel sets to describe the device that was just discovered and then try to find a kernel module that matches that device.

As mentioned earlier, when a driver uses the MODULE_DEVICE_TABLE macro, the program, depmod, takes this information and creates files located in /lib/module/KERNEL_VERSION/modules.*map. The * is a distinction depending on the type of bus the driver supports. Currently, module map files are created for drivers that work with devices that support PCI, USB, IEEE1394, INPUT, ISAPNP, and CCW subsystems.

Hotplug scripts use these module map text files to identify a module to attempt to load it to support a device that was recently discovered by the kernel. They load all the modules and don't stop at the first match, allowing the kernel to choose which module is the best fit. These scripts do not unload all modules when devices are removed. If they tried to do this, they could accidentally turn off devices that are also controlled by the device driver that was removed.

Note that now that modprobe can read MODULE_DEVICE_TABLE information directly from modules without the need for module map files, hotplug scripts can be reduced to a small wrapper around modprobe.

udev

One of the main reasons for creating a single driver model in the kernel was to allow user space to manage the /dev tree in a dynamic style. This used to be done in user space by a devfs implementation, but that codebase slowly rotted due to lack of an active maintainer and some unfixable underlying bugs. Several kernel developers realized that if all the device information were exported to user space, it could do all the necessary management of the /dev tree.

devfs has some very significant design flaws. It requires each device driver to be modified to support it, and it requires the device driver to specify the name and location in the /dev tree where it is placed. It also does not properly handle dynamic major and minor numbers, forcing the device naming policy to be kernel rather than user space. Linux kernel developers really hate having politics in the kernel and since the devfs naming policy does not follow the Linux Standard Base specification, this really bothers them.

Ever since the Linux kernel started being installed on huge servers, many users have been faced with the problem of how to manage a very large number of devices. Disk drive arrays of over 10,000 unique devices present the very difficult task of ensuring that each disk is always named with the same exact name, no matter where it is placed in the disk array or when it is discovered by the kernel. This is the same problem that users are suffering from desktop computers trying to connect two USB printers to their system and then realizing that they had no way to ensure that the printer known as /dev/lpt0 would not be changed to a different printer if the system was rebooted.

Thus udev was created. It relies on all device information being exported to userspace via sysfs and notification via /sbin/hotplug that a device has been added or removed. Policy decisions, such as what name to give a device, can be specified in user space, outside the kernel. This ensures that naming policy is removed from the kernel and allows a greater degree of flexibility in naming each device.

For getting additional information For information on using udev and how to configure it, please see the documentation that comes included with the udev package on your distribution.

All the device driver needs to do for udev to work with it correctly is to ensure that any major and minor numbers assigned to the device controlled by the driver are exported to user space via sysfs. For any driver that uses the subsystem to assign it a major and minor number, this has already been done by the subsystem and the driver does not have to do any work. Examples of subsystems that do this are the tty, misc, usb, input, scsi, block, i2c, network, and frame buffer subsystems. If your driver itself handles getting major and minor numbers via a call to the cdev_init function or the legacy register_chrdev function, the driver must be modified for udev to work with it properly.

udev looks in the /class/ tree in sysfs for a file called dev to determine what major and minor number is assigned this device when called by the kernel via the /sbin/hotplug interface. The device driver simply needs to create such a file for each device it controls. Typically the class_simple interface is the easiest way to do this.

As mentioned in the "class_simple interface" section, the first step in using the class_simple interface is to create a class_simple struct by calling the class_simple_create function:

static struct class_simple *foo_class;

foo_class = class_simple_create(THIS_MODULE, "foo");

if (IS_ERR(foo_class)) (

Printk(KERN_ERR "Error creating foo class.\n");

Goto error;

This code creates a directory in sysfs at /sys/class/foo.

Whenever the driver finds a new device and you assign it a minor number, as described in Chapter 3, the driver must call the class_simple_device_add function:

class_simple_device_add(foo_class, MKDEV(FOO_MAJOR, minor), NULL, "foo%d", minor);

This code causes a subdirectory to be created in /sys/class/foo called fooN , where N is the minor number for that device. A single file is created in this directory, dev , and this is exactly what udev needs to create a device node for your device. When your driver is released from a device and you abandon the minor number that was assigned to it, you need to call class_simple_device_remove to remove the sysfs entry for that device:

class_simple_device_remove(MKDEV(FOO_MAJOR, minor));

Later, when your entire driver is shut down, a call to class_simple_destroy is necessary to remove the class you originally created with the class_simple_create call:

class_simple_destroy(foo_class);

The dev file that is created by calling class_simple_device_add consists of a major and minor number separated by a : character. If your driver doesn't want to use the class_simple interface because you want to provide the subsystem with other files inside the class directory, use the print_dev_t function to format the major and minor numbers correctly for each device.

HotPlug- hot plug) - terms meaning shutdown or connection electronic equipment in/to the (computer) system during its operation without turning off the power and stopping the (system) (HotPlug), as well as replacing (reconnecting) the unit as a whole ( Hot Swap ). There is also a term for the opposite of hot swapping - Cold swap , that is, all (re)connections are made after stopping the system and removing the voltage (residual potential).

Equipment is divided according to this principle into allowing hot swap and not allowing.

Story

Previously, equipment designed to be connected during replacement work was only used in expensive systems and was considered difficult to design. Recently, such systems have become common even on inexpensive computers.

Designed to be hot-swappable and therefore support hot-swappable PCMCIA, USB, FireWire, Fiber Channel and eSATA standards.
Among devices of this type are flash drives, some hard drives, including those for arrays in servers, expansion cards of PCI-X, PCI Express, ExpressCard (PCMCIA, also formerly called PC Cards) formats, which are used in laptops, and even some power supplies .
Does not support full hot swap disk interfaces SATA and does not fully support the IDE protocol (IDE supports hot plugging).

System design

Computers designed for on-the-fly hardware replacement must somehow detect that a device is disconnected and also contain electrical circuits, insensitive to voltage surges when connecting and disconnecting. In addition, the software must be designed for a sudden loss of connection with the device.

Some hot-swappable circuits require a detach command to be issued first, which simplifies the design but compromises data integrity if the device is not disconnected. the right way or it will contain an error.

More complex schemes have a reserve of redundancy and can easily restore data in the event of a sudden device shutdown.

The term "hot swap" has two meanings. On the one hand, it means the ability to disconnect or connect a device without turning off the power. On the other hand, it may also mean automatic detection devices when connected. The first meaning of the term applies to interfaces RS-232, FireWire and the simplest implementations of SCSI, the second meaning - to USB, FireWire, PCI Express and complex SCSI variants.

Nest design

The extreme power pads are made longer than the internal signal pads

In the majority modern devices Hot-swappable, movable contacts are used. One of them is made longer than the others in order to be the first to come into contact with the part being connected; the grounding wire is connected through it. The remaining contacts are made shorter; there can be up to 3 different lengths. The delay between connecting the first contact and subsequent ones is from 25 to 250 milliseconds.

The power circuits are connected in two stages: in the first, the current-limited circuit is connected using longer contacts, and then the full power supply is connected using shorter ones. All circuits involved in the connection are protected against static electricity.

Here is an example of a typical connection sequence:

The longest contacts are closed (grounding). This ensures electrical safety of the connection and protection against static charge.
The long or middle pre-power contacts close. The input circuits of the power circuits are charged.
Short power contacts are connected.
The connection is considered established. The power initialization signal turns on.
The soft power-on circuit supplies voltage to the device.
Delay of tens of milliseconds.
The power circuit has completed soft connection. The power initialization signal turns off.
The device begins full operation.

Connecting several devices is particularly difficult, since connecting a second or third device can disrupt the operation of the already connected one. To combat this phenomenon, filters are used in the output circuits or temporary logical shutdown of data transmission.

Hot plugging in software

The term "hot plugging" is also used in relation to software and refers to the ability to change a program without stopping its execution. Only a few programming languages support this feature, including Lisp, Erlang and Smalltalk. The Java language supports this feature only while the debugger is running ( Java Platform Debugger Architecture (JPDA).

The subject-oriented programming language 1C v8 provides the ability to change code while the program is running. (http://v8.1c.ru/overview/release_8_1_5/administration.htm section "Updating parts of the configuration"). Since compilation of individual modules occurs at the time the program is executed, and when a module changes, it is compiled again in the session, this is not exactly a "hot plug". You need to re-create the session for the changes to take effect, and only for this user (others need to restart a new session). In version v7 this feature was also present when using additional software(http://openconf.1cpp.ru/vk/turbomd/) and the standard command #LoadFromFile....(you only need to re-open the form or report). In general, when using interpreted programming languages (with program texts stored inside modules), “hot plugging” is implemented simply by replacing texts.

We often have to explain to clients that devices with an HDMI interface should not be hot connected. Some people manage to explain this when selling or installing such equipment, but for those who are less fortunate, only after it breaks down.

Today I want to tell you about the subtleties HDMI connections equipment.

Terminology

Term "Hot plugging"(English HotPlug) - means switching ( shutdown or connection) electronic equipment during operation without power outage.

In relation to computers there is a similar term "Hot swap", meaning disconnecting/connecting/replacing system components, again, without first de-energizing.

It is highly not recommended to connect equipment and components “hot”, and speaking of HDMI equipment, it is strictly prohibited!

Device interfaces damaged by hot plugging are called burned or burnt out, and their internal components – punched or burnt.

The reverse term is " Cold connection" (Cold swap) , that is, all (re)connections are made after turning off the power to the devices and removing the voltage (residual potential).

Despite the fact that many users do not bother to unplug devices from the socket when switching, nevertheless, generally accepted practice and safety regulations recommend that any switching be done “cold”! Perhaps someone will want to object and point to the specifications of a number of interfaces or instructions for some devices, where in black and white they talk about the possibility of “hot plugging”. However, with regard to HDMI equipment this can end very badly...

Reasons for HDMI interfaces burning out

Unfortunately, the HDMI interface is extremely sensitive to all kinds of electrical discharges and with a “hot connection”, with a high degree of probability, you can burn the HDMI port or chip of your TV, monitor, video card or any other HDMI device.

What can cause a device with an HDMI interface to burn out when connected “hot”?

The fact is that electrical discharges constantly accumulate on clothing and the human body (static electricity). These discharges, when connecting one device to another, enter the connectors and cause damage to the equipment. The second reason for HDMI damage when connected “hot” is the presence of fairly high potentials on the device housings (about 100 volts). When devices are connected, potential equalization (discharge) occurs, resulting in equipment damage.

Unfortunately, this problem known from the very beginning of the appearance of the HDMI interface and is a consequence of optimized circuit design and the general low cost of components. And, what is quite upsetting, all these shortcomings will be characteristic of new versions of the interface.

Absolutely all devices with an HDMI interface from absolutely all manufacturers are susceptible to this problem. Unfortunately, neither the big name of the brand nor high price devices do not guarantee 100% security in this matter. Therefore, if you don’t want to say goodbye to your device or a tidy sum of money, you should follow the connection rules unconditionally!

Examples of damaged HDMI devices

If a discharge enters the device, both the HDMI port itself and other elements may be damaged: chips, air conditioners, microcircuits.

Trying to independently understand the causes of the breakdown and opening the “dead” device, you may not be able to visually replace the damaged hardware. But sometimes you can’t argue with the diagnosis...

Functional and burned out HDMI port. Feel the difference.

Burnt out HDMI port from the inside.

Burnt resistor.

Moreover, the main control chip or several at once burn out, which makes repairing the equipment impractical (due to its high cost) or even impossible.

Broken chip.

Another victim of hot plugging.

Three simultaneously “punched” chips.

A very bad option.

I hope you don't encounter similar troubles.

What about protection, you ask?! Naturally, developers install protection for HDMI interfaces, but, unfortunately, it only saves from slight “static”. Unfortunately, there is no protection against more serious discharges that are present everywhere. I repeat, even equipment from top brands suffers from “hot plugging” via HDMI.

Rules for connecting HDMI equipment

Having properly frightened the reader, we came to the main part of our article: How to secure equipment with HDMI interfaces?

Exist general rules correct connection electronic devices:

Disconnect all connected equipment from power. Moreover, not just turn it off with a button on the remote control or a toggle switch on the rear panel, but turn it off from the outlet!
Connect equipment using cables. This applies to both HDMI cables and others, for example, audio, Ethernet and other cables.
After this, plug all system devices into a power outlet.
Only after this can you use the equipment.

Keep in mind that if you need to reconnect any of the system elements or add new equipment to it, the entire sequence of actions should be repeated.

It would seem nothing complicated. The whole procedure will only prolong the connection process by a couple of minutes, but if you knew how often the notorious human laziness and hope for “maybe” force people to neglect these simple rules, and waste a lot of nerves, time and money.

Protection of HDMI interfaces

But there are cases when it is absolutely impossible to switch equipment “cold”. For example, when it comes to HDMI extenders and between devices over a distance of several tens or even hundreds of meters; when in a large store several dozen televisions are connected at once, operating throughout the entire sales floor, and the manager urgently needs to demonstrate to the buyer the functionality of some product; when there is a live broadcast in a sports bar; when HDMI equipment is used for video broadcasting and other, most often non-domestic, cases. In this case, it is recommended to use special HDMI interface protection devices.

Protection of HDMI ports Dr.HD

These passive elements (fuses) are used to protect devices with HDMI interfaces from electrostatic discharges, potential differences when connecting equipment “hot”, as well as lightning pickups. They are active on all TMDS channels and will act as the ultimate ESD protection. At the moment when the discharge goes through the cable, this “baby” will take the entire blow.

In principle, if you are not afraid of extra costs, such fuses can be used in everyday life. They need to be installed on one side of each HDMI connection.

HDMI interface burnout

20.03.2017

admin

Today I want to tell you about the intricacies of connecting HDMI equipment.

Terminology

Term "Hot plugging"(English HotPlug) - means switching ( shutdown or connection) electronic equipment during operation without power outage.

In relation to computers there is a similar term "Hot swap", meaning disconnecting/connecting/replacing system components, again, without first de-energizing.

It is highly not recommended to connect equipment and components “hot”, and speaking of HDMI equipment, it is strictly prohibited!

Device interfaces damaged by hot plugging are called burned or burnt out, and their internal components are punched or burnt.

The reverse term is " Cold connection" (Cold swap) , that is, all (re)connections are made after turning off the power to the devices and removing the voltage (residual potential).

Causes of burnoutHDMI interfaces

What can cause a device with an HDMI interface to burn out when connected “hot”?

Unfortunately, this problem has been known since the very beginning of the HDMI interface and is a consequence of optimized circuit design and the general low cost of components. And, what is quite upsetting, all these shortcomings will be characteristic of new versions of the interface.

Absolutely all devices with an HDMI interface from absolutely all manufacturers are susceptible to this problem. Unfortunately, neither the big name of the brand nor the high cost of the device guarantee 100% safety in this matter. Therefore, if you don’t want to say goodbye to your device or a tidy sum of money, you should follow the connection rules unconditionally!

Examples of damagedHDMI devices

If a discharge enters the device, both the HDMI port itself and other elements may be damaged: chips, air conditioners, microcircuits.

Functional and burned out HDMI port. Feel the difference.

Burnt out HDMI port from the inside.

Burnt resistor.

Moreover, the main control chip or several at once burn out, which makes repairing the equipment impractical (due to its high cost) or even impossible.

Broken chip.

Another victim of hot plugging.

Three simultaneously “punched” chips.

A very bad option.

I hope you don't encounter similar troubles.

Connection rulesHDMIequipment

Having properly frightened the reader, we came to the main part of our article: How to secure equipment with HDMI interfaces?

There are general rules for properly connecting electronic devices:

Disconnect all connected equipment from power. Moreover, not just turn it off with a button on the remote control or a toggle switch on the rear panel, but turn it off from the outlet!
Connect equipment using cables. This applies to both HDMI cables and others, for example, audio, Ethernet and other cables.
After this, plug all system devices into a power outlet.
Only after this can you use the equipment.

Keep in mind that if you need to reconnect any of the system elements or add new equipment to it, the entire sequence of actions should be repeated.

Protection of HDMI interfaces

Protection of HDMI interfaces

In principle, if you are not afraid of extra costs, such fuses can be used in everyday life. They need to be installed on one side of each HDMI connection.

You can

21.07.2020

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