Owner: Scienceprog - Embedded Related Info URL:http://www.scienceprog.com Join Date: Thu, 31 May 2007 02:24:58 -0500 Rating:0 Site Description: Site is loaded with AVR, ARM microcontroller related information. Many projects including UV exposure box manufacturing, AVR signal generator, DTMF decoder.
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How to solder SMD at home-Part one 2007-05-23 05:38:38 Soldering SMD parts isn’t hard task and there are many methods of doing this. Lets go through several SMD soldering methods and examples.
Method 1
For this you will need:
Good eyes or magnifying glass. Better one and another;
Soldering iron with small tip ~10W;
solder wire with diameter about 0.6mm
Steps to follow:
cut solder wire in pieces in length of element width:
Put SMD element on circuit bord where it has to be soldered:
Put solder wire piece next to SMD:
While holding SMD component with pincet solder part to the board by applying iron to the solder;
Once one end is soldered repeat same procedure with another end of SMD element:
Method 2: soldering SMD in the oven
This method is handy when you need to solder SMD packages like LQFP, TQFP64 and so on. If you don’t have special oven for soldering SMD then you can use one that you find at home. Of course take all safety precautions while working with ovens
Very simple IR detector that controls relay 2007-05-23 03:59:17 The circuit of this Infrared(IR) detector circuit is a simple light relay which triggers when infrared light is applied to phototransistor Q1. This device can be used in control systems. When infrared light is OFF, Q1 transistor and relay K1 are normally closed.
When IR diode is transmitting IR light phototransistor Q1 opens and thus relay K1 triggers because current starts flowing through Q2 transistor. Construction can easily be modified when circuit output is connected to microcontroller or other device. Sensitivity so the distance can be controlled by changing IR diode D1, using more sensitive phototransistor Q1 and adjusting R2 resistor.
Original source: http://cxem.net
How PCB files are transfered to circuit boards 2007-05-21 10:20:57 When you are done with “clean” period of task – designing, drawing a circuit and tracing a PCB, you need to transfer a design to a real board. Here starts what I call a “messy” part of design. When designing at home there are several options - to use prototyping boards or make PCB by yourself. In second option you have to transfer PCB image to board with copper layer. There are several methods of doing this: direct transfer with glossy paper where image is printed with laser printer or use more advanced ultraviolet exposure. This way PCB image is printed on paper or film directly from program window without keeping in mind about pcb file formats. Different situation iswhen fabricating professional PCB’s. Each company which fabricates PCB boards always announce what type of file formats they support. So if you are going to order a PCB better check with them in order to save your time.
The most common and standard format is so called Gerber file format. Almost all layout Read more:files
, transfered
Protect you car from rusting using cathode protection 2007-05-16 04:36:32 Who has a car know that smal scratch may cause a rusting which will expand even under painted areas. And fight rusting id pretty hard tas. And so there are lots of methods that car keepers using. Ones are using anti-rust coating… but it has shortcomings – succes depends on how good it have been done. Area needs to be cleaned with care and sometimes requires to to pieces a car. So such operation requires decent amount of time and requires constant control. Besides this car is always in stressed environment: cold, salt, water, vibrations, stones and so on. There is always a chance of damaging surface coating. Because of this there came a device which requires only one installation which protects from rust.
Cathode rusting protection isn’t new thing. It has ben used for protecting various object on and under ground. Even ships are using cathode protection. The idea is to use special protector who melts in sour water instead of protected metal. Water piping companies who use Read more:Protect
How does tri-state buffers work 2007-05-04 09:58:07 Those who work with microcontrollers probably know about data buses. Only one device(memory, peripherals), that are connected to bus can work at one moment. So only one unit can have direct connection to bus besides CPU which usually is a host. So decoding circuit determines the desired unit and connects it to bus. Other devices are effectively disconnected so that they wouldn’t have any affect to bus operations. They are carried out by tri-state buffers.
Tristate buffers allow to isolate circuits from data bus. This means that circuit is switched to high impedance state. Usually we know dual state circuits that can have two logical levels “0” and “1”. But there is also widely used tristate logic, where is ability to switch I/O to high impedance state.
Tristate logic can simply be made by two transistors:
Using such circuit we can have following output results according to input variations:
Q1 Q2 Output
OFF OFF High Impedance
OFF ON
32 bit microcontrollers from ATMEL with ARM7 core 2007-06-06 04:23:02 Somehow I’ve been sticked to NXP LPC2xxx series microcontrollers and left other brands behind. There are many major manufacturers of ARM microcontrollers. One of them that is worth to pay attention is Atmel with its AT91SAM7 (Smart ARM7) series. SAM7 series of microcontrollers have built in Flash memory and data memory as well. Core is powered with 1.8V while peripherals need 3.3V. Core voltage is converted inside the chip so you don’t have to bother about this and only apply stabile 3.3V voltage. SAM7 microcontrollers are based on ARM7 core so they have very good performance characteristics. SAM7 microcontrollers differ from other brands with their ability to access memory directly (DMA), so each microcontroller peripheral have distinct two channel controller. LPC series only have AMBA bridge between AHB and LHB.
Main characteristics of AT91SAM7 series:
very good ratio between performance and poer consumption;
performance up to 60MIPS;
ARM/THUM command support;
New ARM7 Microcontrollers from NXP with LCD support 2007-06-06 03:32:30 New microcontroller LPC2478 from NXP company is based on ARM7 core with built in Flash memory and have built in LCD interface. LPC2470 has no Flash memory.
LPC24 series have two high speed buses AHB to ensure independent work of peripherals like LCD, 10/100 Ethernet, USB and two channels of CAN. LPC24xx have reasonable low prices that allow these MCU to be used in industries like various gadgets, home appliances, medical equipment where LCD is required and also connection to the internet.
LCD displays are part of our life starting from cell phones, media players and car navigation systems GPS. LCD takes important part in medical environment. Where visual information may be critical. So LPC2478 and LPC2470 goes in front of non expensive and low requirements for LCD interfacing.
LPC2478 and LPC2470 supports most of statical LCD displays up to 1024×768 pixels monochrome with fifteen gray levels and color 24bit/pixel TFT panels. Designers of embedded systems have to program L
What is DebugWire interface 2007-06-05 03:34:59 Debug wire is an interface which enables debugging AVR microcontrollers by using one wire. All new AVR microcontrollers with less than 16kByte memory have built in one wire bidirectional debugging interface which allows debugging devices at the real time.
Like JTAG interface DebugWIRE can handle full execution and program flow control. It also supports unlimited number of breakpoints, adjusting memory contents. Good thing is that interface doesn’t require additional pins as only RESET pin is used for debugging purposes.
To enable debugwire interface DWEN fuse has to be programmed also lock bits has to be un-programmed. Then RESET port pin is activated as open-drain bi directional I/O pin with pullup enabled. Reset pin becomes communication gateway between target and emulator. When debugging external reset circuitry should be disconnected – so no external reset source will be present during debugging.
Debug wire adapter-debugger communicates through one data register DWD
Chemical effects of electricity 2007-06-29 05:59:12 Electronics depend on chemistry more than you can imagine. In order to generate electricity
there are many methods used, one of them is chemical. Remember batteries, where electricity is generated because of chemical reactions inside cell. Also in conductors like liquids and gases electricity is carried not by electrons as it is in solid constructions(copper, aluminum, etc.), but by ions – molecules with electric charges. Even non distiled water contain enough ions to be conductive. Lets go through several chemical effects of electricity.
Electrolysis
Electrolysis is a decomposition of liquid compound by passing electric current through liquid called electrolyte(salt water, copper sulphate, sulphuric acid). Electrolysis is used very widely in industry like electroplating of metals, refining of copper and extraction of aluminum from ore. To make electrolysis happen there are two conductors used cathode(-) and anode(-).
Electrolysis is one of simplest ways to produce hydroge
Controlling graphical 128×64 LCD based on KS0108 2007-07-20 10:50:14 HQM1286404 is pretty old graphical LCD module but it is still popular. This LCD is controlled by KS0108 lcd controller via two segment drivers. LCD backlight color is yellow-green. I think this is good choice for many projects where graphical information needed because of several reasons – you can find libraries around the internet to start working in just a few minutes, also there are several tools that can be used to generate character arrays and graphics.
Hardest thing for me was to find correct wiring as datasheet I have was for next PCB revision (HQM1286405) as mine are HQM1286404 so done be mistaken as I did. Here is the correct pin-out of LCD:
1 Vcc
2 GND
3 Vee
4-11 DB0-DB7
12 CS2
13 CS1
14 RESET
15 R/W
16 D/I
17 EN
18 Read more:Controlling
What are MEMS 2007-07-31 05:49:39 Today MEMS is common acronym among engineers. Therm MEMS stands for micro-electro-mechanical system and was started to use in 1980sin USA. MEMS are called system because they are not only sensors bu also contain electronic circuitry inside which conditions sensor signal. Simply speaking MEMS is usually a chip device which integrates mechanical elements, sensors, actuators and electronics. Most interesting and important partis mechanical. Miniaturisation of mechanical part using micro-machining technologu when selectively parts are etched away, it became possible to create mechanical structures on silicon base together with electronic devices.
MEMS devices are used everywhere today including automotive, industrial even computer hard drives have MEMS sensors for shock protection. Ability to integrate mechanical sensors inside chip made possible to design compact accelerometers, gyroscopes, pressure sensors, sensors with integrated RF, and meny more. Also technology enables to in
Reliable soldering with fluxes 2007-08-01 08:10:14 Reliable soldering can be achieved by soldering clean surfaces. Usually surfaces are cleaned with abrasives and solvents, but after surface is cleaned surface immediately oxides especially when heated. During oxidation surface is covered by thin oxide film which prevents solder from contacting to metal. This is why flux is used in soldering process. In order to remove/deoxidize surface flux must be applied during soldering. Flux chemically removes surface oxide when heated and makes good metal to solder contact.
(Image source: http://www.tpub.com/neets/book4/12o.htm)
There are several categories of soldering fluxes:
Acid Flux (or commonly known fluxes: Zinc chloride, hydrochloric, ammoniac);
Organic Flux;
Rosin Flux.
Each flux has their own specifics and may be used for different soldering technologies.
Acid Flux
Acid Flux is most active of the group. It is effective on almos all metals excluding aluminum and magnesium. But Acid(chloride) flux has several significant d Read more:Reliable
AVR based TDA7313 Audio processor control 2007-08-08 16:10:10 Introduction
TDA7313 audio processor
have been used for more than ten years in the industry because of its simplicity, functionality and good parameters like low distortion, low noise. Chip is based on BIPOLAR/CMOS technology and can be used in various applications including car radios, Hi-FI, simple mixers.
TDA7313 chip has 3 external stereo inputs, that allows to multiplex three incoming sound sources, volume control with steps of 0.25dB, Treble and BASS control, Laudness function, Each of four outputs have distinct control that allows to balance outputs. Chip can be controlled via I2C (TWI) interface.
Description
The idea of this project was to construct independent audio processor which can be embedded in any audio system with ability to control settings with simple button interface with menu preview in LCD.
The intent was to cover all audio-processor functionality within LCD menu.
Circuit and PCB
Circuit diagram is pretty the same as in datasheet plus Atmega8 control circu Read more:Audio
Oscilloscope probes for accurate signal measurements 2007-08-15 14:07:02 Oscilloscope Probes
Measuring signal
s with oscilloscopes may be challenging task especially high frequency ones. Without proper oscilloscope probes correct measurement of high speed time domain signals wouldn’t be possible. For high speed measurement you should consider signal parameters like amplitude, source impedance, rise time and bandwidth.
There is a wide variety of probes available – passive, active, current-measurement, optical, high voltage and differential. But let’s narrow discussion to probes that are used to measure signals with wide bandwidth and short rise times. There are also many variations on what probe is proper. As probes are potential load to measured circuit, it is important to know its sensitivity to resistive, capacitive or inductive loading. Incorrectly chosen probe (like high capacitance) can distort fast rising signal. Some circuits may not tolerate probes at all (high speed amplifiers).
(more…)
DIY USB to RS232 adapter 2007-08-27 03:53:32 Sometimes you just need to connect some device to COM port, but computer don’t have one especially laptop. There are two ways – go and buy USB – COM adapter or build one. So if you decided to build USB to COM(RS232) adapter, there is one of solutions.
This adapter is very easy to build as there is single chip USB to UART bridge (CP2102) used. This chip from Silicon Labs support USB2.0 full speed, has internal Resistors required for USB interface, integrated clock, internal 1024 -byte EEPROM for vendor ID, Product ID serial number, power descriptor and other information. SP2102 USART part support almost all standard features of RS232 communication including handshaking, Databits (5, 6, 7 and 8); 1 or 2 stop bits; odd, even, mark, space and no parities; baud rate from 300bps to 1Mbits.
(more…)
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