Various diagram: usb

Showing posts with label usb. Show all posts

Wednesday, November 19, 2014

Type of USB connectors

USB connector there are only 2 kinds, namely the connector type A and type B connector, as shown below. Type A connector used to connect the USB cable into the USB terminal on the back of the computer the last few years of production. Type B connector used to connect the USB cable into the USB terminal on the equipment, for a simple USB devices, such as mouse, usually do not use the connector B, to save cost in the cable directly connected to the inside of the mouse.

Specified in the standard reference pesyaratan very strict to USB cable, not just the cable can be used, all the more for USB full-speed transfer of data to 1.2 Mega bps. So that the USB cable always sold as a ready-made, one end attached to the connector type A and the other end attached to the connector type B, no one sells it off the USB connector.

On the computer, usually there are two terminals for connector type A, so it can easily be paired with 2 pieces of USB devices. Manufacturing company that makes the mother board there is an additional USB terminal, you can buy if you want to add more than 2 USB devices. USB terminal on the computer named as Root Hub Another way is to use a USB hub as shown in the figure, in this way can one USB terminal on the broken into four.

Each of these fractions can also be connected to another USB Hub, as well as onward connection to connect to as many as 7 levels, which could eventually connect to 128 pieces of USB devices!

USB FX2 USB 2 0 interface board circuit schematic

USB-FX2 USB-2.0 interface board circuit schematic

There are some things one should be aware of when building the design above:

Resonator: According to the data sheet, the FX2LP has an on-chip oscillator circuit which requires an external 24MHz (±100ppm) parallel resonant, fundamental mode crystal with 500uW drive level and 12pF (5% tolerance) load capacitors. So, you cant just put any 24MHz crystal there but things dont seem to be as critical as one may expect. Im using a 24MHz fundamental mode crystal (24-MA505 from Reichelt) with 10..15pF caps (or even 32pF).
(Note: In the schematic above, there are 2 crystal oscillators in parallel merely to have both options on the PCB (one of them is an SMD). Only one of them is actually soldered onto the board.)
EEPROM: You can use an optional serial EEPROM to store either USB configuration data or a complete program which is loaded into the microcontrollers RAM at startup. You can leave it away completely to use default USB config data and download firmware via the USB (thereby also changing, the config data, its the so-called ReNumeration thingy). Note, however, that if you leave away the EEPROM, you must still put in both the 2.2k I²C bus pull-up resistors.
PWR_SEL: For USB-powered operation (500mA max), close a jumper between pins 2 and 3, for externally powered operation, apply 5V and GND to pins 2 and 1, respectively. There is an additional 5V, 3.3V and GND power connector called PWR_HUB to connect with add-on boards.
For 5V-to-3.3V conversion, you need to use an LDO (low-dropout regulator) like the LM2937. It should have a drop-out of 1.2V max since the USB specs allow the 5V voltage to be as low as 4.5V on the slave side.
Of course, usual voodoo applies like putting decoupling caps near by and keeping the USB data lines short. A massive ground plane is mandatory, at least for the analog half. Forget about Cypress telling you that you need at least a 4-layer PCB. My regular 2-layer PCB (ground plane on bottom) works stable in high-speed mode even with 3m USB cable.

Source : www.triplespark.net

Friday, November 14, 2014

How to Build a UPS for USB devices

Portable systems often include circuitry that derives power from an external source, such as USB. When the system disconnects from the USB supply, a battery takes over and supplies current via a dc/dc converter. A diode-OR connection (Figure 1 offers the easiest way to ensure that the supply voltage doesnt sag during this switchover to the battery. The diodes forward voltage drop, however, can reduce battery life and efficiency.

A diode-OR connection is effective but lossy.

A boost-converter circuit is an improvement over the simple diode-OR connection.

The single-cell, boost-converter circuit with external PFET (Figure 2) is an improvement over the diode-OR connection. The PFET, Q1, coupled with IC1s internal gain block, forms a linear regulator. The USB power supply has a diode-OR connection to Q1s source. Setting the boost converters output to 3.4V allows the drain of Q1 to regulate to 3.3V. This configuration produces negligible loss in Q1. The bus-supply voltage available to USB devices ranges from 4.4 to 5.25V.

When you connect the bus, it forward-biases D1 and causes the boost converter to idle. The converter continues to idle as long as its output remains above the 3.4V regulation point. The bus supply serves the load and activates the current source to charge the battery.

Adjusting R1 allows you to set the current-source output to charge the nickel-metal-hydride cells at a level one-tenth the batterys capacity. Disconnecting the circuit from the USB supply causes the boost converter to cease idling and supply current to the load via the battery. Figure 3 shows that the load current suffers no interruption during a switchover from USB to battery.

Saturday, November 8, 2014

USB Powered PIC Programmer

This simple circuit can be used to program the PIC16F84 and similar "flash memory" type parts. It uses a cheap 555 timer IC to generate the programming voltage from a +5V rail, allowing the circuit to be powered from a computer’s USB port. The 555 timer (IC1) is configured as a free-running oscillator, with a frequency of about 6.5kHz. The output of the timer drives four 100nF capacitors and 1N4148 diodes wir-ed in a Cockroft-Walton voltage multiplier configuration.

Circuit diagram:

USB-Powered PIC Programmer Circuit Diagram

The output of the multiplier is switched through to the MCLR/Vpp pin of the PIC during programming via a 4N28 optocoupler. Diodes ZD1 and D5 between the MCLR/Vpp pin and ground clamp the output of the multiplier to about 13.6V, ensuring that the maximum input voltage (Vihh) of the PIC is not exceeded. A 100kΩ resistor pulls the pin down to a valid logic low level (Vil) when the optocoupler is not conducting. The circuit is compatible with the popular "JDM" programmer, so can be used with supporting software such as "ICProg" (see http://www.ic-prog.com).

Saturday, October 11, 2014

Power Supply for USB Devices Circuit Diagram

More and more equipment is sold that runs off internal rechargeable batteries. Although a matching charger is usually supplied in the package, there are also devices that can only be charged via a USB port. That is not surprising in the case of USB MP3 players, which have to ‘dock’ in the PC anyway for some time for the purpose of file transferring. Still, the same ‘feature’ can be a serious disadvantage, for example, on ‘computer-free’ holidays. Sometimes it makes you wonder how simple the solutions to such problems actually turn out to be. After all, if it’s just a supply volt- age we’re after, then a USB port is easily imitated.

Circuit diagram :

Power Supply for USB Devices Circuit Diagram

The circuit shown here is nothing but a 7805 in a dead standard configuration. The innovation, if any, might be USB connector to which the MP3 player can be connected. The 7805 comes in different flavours — most devices can sup- ply 1 A, but there are also more advanced variants that achieve up to 1.5 A. Because a USB device is never allowed to draw more than 500 mA from the port t is plugged into, the circuit shown here should be able to supply charging and/or operating current to up to two (or three) USB devices at the same time. The input voltage may be a direct voltage of anything between 7 and 24 volts, so for use at home or abroad a simple wall cube with DC output is sufficient.

Another useful bit to make your-self might be a cable with an in-line fuse and a cigarette lighter plug so you can tap into a vehicle supply (note that this may be up to 14.4 V with a running engine). At an output current of 1 A and an input voltage of just 7 V, the 7805 already dissipates 2 watts. Assuming you’re using the most commonly seen version of the 7805, the TO-220 case with its metal tab will have a thermal resistance of about 50 °C/W. Also assuming that the ambient temperature is 20 °C, the 7805’s internal (chip) temperature will be around 120 °C. In most cases, 150 °C is the specified maximum, so ample cooling must be provided especially in a car and with relatively high input voltages.

Friday, September 26, 2014

USB Enabled Remote Control

The objective of a remote control is to have the ability to operate a device from a certain distance. Nevertheless, remote controls usually are in places where we need to move around to find. This makes the remote totally useless as you may have used that time and energy to operate the device personally. If we take into account the limited reach that remote have, along with the fact that they are battery operated, we have an obsolete technology. All this can be fixed by developing a new remote control system.

A lot of designs have been completed on systems that operate by clapping. But they have some disadvantages. Such as the fact that they work over only one sound or command. Another fact is that daily activities must be interrupted to give a command.

A whistling command system has been developed to control domestic devices. It works by detecting the sound peaks that are uniquely produced by whistles. Sound from each whistle is processed to give the order to the device.

The sound is received by a mic placed in the room. The microphone is connected to a USB device that transfers the information to a Linux operated computer. Once the command is recognized, the computer sends it to the device.

Thursday, September 18, 2014

USB Powered PIC Programmer

Circuit diagram:

USB-Powered PIC Programmer Circuit Diagram

Author: Luke Weston - Copyright: Silicon Chip Electronics

Sunday, September 7, 2014

USB Charger For Lithium Ion battery

USB Battery Charger For Lithium Ion battery with the LM3622 is a series of lithium ion battery charger. This charger circuit operates using power from the USB source PC.

Wednesday, August 27, 2014

USB powered battery charger circuit

At this time I will share about the series used in the usb to charge battery. Issued voltage 4.7 Volt to 5 Volt DC suitable for battery charge the phone, as well as other batteries.

Below is a circuit where the voltage is removed the usb on the computer will be strengthened by several components so that the voltage used to charge batteries more powerful and filtered, and will make it more durable and long lasting.

Part List :

R1 = 1 K

R2 = 330 R
R3 = 4K7
R4 = 300 R
R5 = 27R
D1 = 4.7 volt zener /1W
C1 = 100uF/16V
Q1 = BC548
Q2 = BC558A