Control AT89C2051 A Serial to Parallel Converter

The converter runs at 9600 baud, 89C2051 and outputs each byte received on a centronics style parallel port, together with a nominal 50 microsecond strobe. The converter buffers up the bytes received if busy is active, and is bidirectional – when the sample switch is pushed, the converter samples the parallel port and transmits the value back out the serial port. All the parameters are adjustable in the code. This is the figure for the connection circuit;

The example program should be assembled with the shareware assembler TASM. This assember is actually a very good assembler for 8051, (and other 8 bit micros) with 32 bit arithmetic, and a linux version available. TASM is produced by Squak valley software. The serial-to-parallel example program was intended to run on an AT89C2051 using the prototype board that was originally supplied as part of the evaluation kit in our programmer. But the circuit is pretty darn simple, and a competent electronics person could build one up themselves, by hand, if they need to. The code should run on any 8051 target with modification to the port locations – the equates for the pin & port locations are near the start of the code.

Note the pin functions are not shown on the circuit, as the circuit was intended to be a general purpose evaluation board, not just a serial to parallel converter.

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Control Color BAR Generator Circuit Using AT90SXX

This is a design circuit for color BAR generator circuit. The circuit (see Color bar Schematic.jpg)it is constituted by AT90s2313 running at 17.734475 MHz (over clocked) and one, 5 bits DA converter (R2R-ladder) with 10 resistors. This is the figure of the circuit;

Program the MCU with colour_bar_gen.hex that its included in colour_bar_gen.zip file, connect it on composite video connector (or scart adapter) of your TV, power-on the circuit and you will see on TV, 6 vertical bars, 4 in color, 1 white and 1 black.

Partlist
1 x AT90s2313
1 x 17.734475Mhz crystal
2 x 22 pF condensator
6 x 1 kOhm resistor
4 x 500 Ohm resistor

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Control 2 Channel RF Remote Control Transmitter Using AT90S2323

This is the transmitter circuit that is controlled by microcontroller AT90S2323. This circuit is work based on TLP434 RF transmitter module at 418MHz. This circuit is design using low power supply that is for more battery economy and safe transmition of the data. Here’s figure of the transmitter circuit.

If you press the S2 key, the logic of this pin goes to '0' (0V) and AVR awake frome the sleep mode (because PB1 is INT0) and check if pressed the S1 key. If not, the AVR take as pressed key the S2. If yes the AVR take as pressed key the S1. If you press the S1 key the logic of this pin and PB1 (through 1N4148) goes to '0' (0V). In this case the AVR take as pressed key the S1. After, calculate the checksum and transmit 4 times the same 4 byte sequence to make sure that receiver takes the data and goes to sleep mode until next interrupt on PB1. When the INT0 pin (PB1) of AVR goes to 0V, the transmitter TLP434A is working. If you stop press the switch S1 or S2, the TLP is stop working. The safe transmition of the data based to transmition of 4 bytes with serial form at 2400 bps (bits per seconds). 1st and 2nd byte are for recognition of valid remote control from receiver (like ID bytes), 3rd byte is command byte. The relays status dependet by the value of this byte. Finally, the 4th byte is the checksum of the earlier 3 bytes.

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Control 2 Channel RF Remote Control Receiver Using AT902313

If the article before is about transmitter, so this is the receiver for the RF remote control. This circuit is using RF receiver module RLP434A at 418MHz. This circuit is control using microcontroller. The 2 relays with can handle any electric (or electronic) device up to 10 Amps (the contacts of my relays are 10Amp at 250Volts). Here’s the figure of the circuit.

The RLP434A is an RF receiver module with receipt frequency at 418MHz with ASK modulation. There are 2 outputs from this module, the digital, with levels from 0v to VCC (5 volts in our case) and the analog output. Analog output is not used. The transmitter send 4 bytes with 2400bps 4 times and the receiver RLP-434A, collect them and move them to AT90S2313 to RxD pin, PD0. AT90S2313 use a hardware UART adjusted at 2400bps and the hardware the UART is more stable, with smaller code, than software UART that I use in the transmitter. If some serial data arrive at the middle-time of some other routine other than receive routine, for sure we will loose this bits of data. The hardware UART does not have this problem because have buffer for this (UDR register).

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Control Audiometer Circuit Using Microcontroller AT89S51

This is a design for audiometer circuit. This audiometer is an instrument used for the diagnosis threshold of human hearing to give some particular audio frequency and also a certain level of intensity. Raised from the signal generator sinus and selected using a multiplexer 4051. Amplitude or intensity of sound can be arranged through the DAC. Use as bait with the audio signal. Voltage to references from the DAC, so the output can be set with accuracy Vref/255. This is the figure of the connection of the circuit.


Procedure for programming the audiometer circuit is initial view will display the form fields Name and Date patients now on the Character LCD screen, which can be entered via the keyboard. After the data in the content of the system will wait for the emphasis the Enter key when keyboard enter key is pressed the system will start working on procedures audiometer. Through the multiplexer 4051 then selected the most low frequency, 125 Hz and data on the issue with the DAC will be issued with the signal frequency and amplitude particular. Interruption through the system timer 0, mode with 16 bit then remove the signals that can be set to increase amplitude for every 10 seconds: 0:05 x 200 = 10 seconds if the patient does not press the button, when 10 patients amplitude still does not listen to the sound of the automatic frequency raised to a higher level and again at the lowest amplitude. By using an external system interruptions 0, then we can do so that interruptions can be patient when the system starts listening to a sound. When patients hear then press the button so that there will be a process data storage dB and Frequency at the time. When the process is completed the system will re-open the data-data that have been stored for the data storage process is done.

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Control Temperature Indicator Circuit

This circuit uses a Dallas DS1621 temperature sensor which indicates the temperature of the device. The temperature sensor has a thermal alarm output, which becomes high when the temperature of the device exceeds a user defined value. This is the figure of the circuit.


When the temperature drops below a user defined value, the alarm output becomes low. In this way any amount of hysteresis can be programmed. The values are stored in a special register of the device that is nonvolatile. The signal of the alarm output is amplified by a BC557 PNP transistor, that is drives a relay that can switch a heater element or a blower on or off. The temperature settings and readings are communicated to/from the device over a simple 2-wire serial interface. An ATMEL 90S2313 microcontroller controls the serial communication to/from the DS1621.The microcontroller also controls three LED, only one of the LED's is on when the temperature is within a certain range. The range of the temperature in which the LED's are on can be set by the user in the program code. The circuit needs to be powered by a 5V power supply, which can be obtained from a wall-wart.

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Control A Digital Thermometer Using AT89C2051

The system presented in this application note implements a simple digital thermometer that includes a built-in LCD and RS-485 communicate ion Port. It is designed around Atmel’s AT89C2051 processor, a digital thermometer/thermostat from Dallas Semiconductor, a small 8 X 2 LED backlit LCD, and an RS485 line interface. The system, shown in Figure, can be used as the basis for developing custom solutions for networked and stand alone data collection and control equipment. It can be centrally powered due to its low current requirement and its small size allows it to be placed almost anywhere.


Temperature acquisition is handled using the digital thermometer/thermostat IC from Dallas Semiconductor. The digital contains all temperature measurement and signal conditioning circuitry on-chip and presents the processor with a 3-wire digital interface composed of a bi-directional data line DQ, a reset input \RST, and a clock input CLK. The temperature reading is provided in a 9 bit, two’s complement format. The measurement range spans from -55°C to +125°C in .5°C increments. Data transfers into and out of the DS1620 are initiated by driving \RST high. Once the DS1620’s reset is released, a series of clock pulses is emitted by the processor to actually transfer the data. For transmission to the DS1620, data must be valid during the rising edge of the clock pulse. Data bits received by the processor are output on the falling edge of the clock and remain valid through the rising edge. Taking the clock high results in DQ assuming a high impedance state. The sequence can be immediately terminated by pulling \RST low which forces DQ into a high impedance state and concludes the transfer. Temperature data is transmitted over the 3-wire bus in lsb first format. A total of nine bits are transmitted where the most significant bit is the sign bit. If all nine bits are not of interest, the transfer can be terminated at any time by asserting \RST.

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Control temperature indicator with ATMEL 89C51

Description of feature devices;

• Measures temperatures from -55 degrees C to +125°C
• Three LED's to indicate in what range the temperature
• User definable thermostat with high and low settings
• Output via a relay to control a heater element or a blower fan (or something else)
• Power supply......................4.5 to 5.5 VDC
• Power consumption ...........15mA

This schematic device uses a Dallas DS1621 temperature sensor which indicates the temperature of the device. The temperature sensor has a thermal alarm output, which becomes high when the temperature of the device exceeds a user defined value. When the temperature drops below a user defined value, the alarm output becomes low. In this way any amount of hysteresis can be programmed. The values are stored in a special register of the device that is nonvolatile. The signal of the alarm output is amplified by a BC557 PNP transistor, that it drives a relay that can switch a heater element or a blower on or off. The temperature settings and readings are communicated to/from the device over a simple 2-wire serial interface. An ATMEL 90S2313 microcontroller controls the serial communication to/from the DS1621.The microcontroller also controls three LED, only one of the LED's is on when the temperature is within a certain range. The range of the temperature in which the LED's are on can be set by the user in the program code. The circuit needs to be powered by a 5V power supply, which can be obtained from a wall-wart.

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