Rs232 Interface | Electronic Project Circuits

Posts Tagged ‘rs232 interface’

Central Heating Programmer with serial PC interface

This programmer has been designed for use with a domestic heating boiler. It provides outputs via two relays to control the supply of Hot Water and Heating. There are 10 program entries available and each one can control the heating and water independently. The programmer allows manual advance of the heating and water and disabling of program control, useful if you’re going away for a few days and want to leave the heating and water off. As well as providing normal front panel switch control of the heating and water, the programmer also features a serial terminal interface that allows it to be operated remotely from a PC running a Terminal Emulator.

Read Source: http://picprojects.org.uk/projects/chc/chprgrammer.htm

Be the first to comment - What do you think? Posted by admin - June 7, 2009 at 11:15 am

Categories: Microcontroller Tags: programmer circuit, rs232 interface, serial PC interface

PIC to RS232 Interface

The circuit shown will convert logic level voltages to and from RS232 serial voltages levels. For basic serial comms between a Microchip PIC and a PC or other device you generally only need to connect the Gnd, Txd and Rxd lines. This little circuit will work with a supply voltage of 3.3v to 5v making it ideal for interfacing with a PIC
Read More Source: http://picprojects.org.uk/projects/simpleSIO/ssio.htm
Thank you.

Be the first to comment - What do you think? Posted by admin - May 29, 2009 at 7:10 am

Categories: Microcontroller Tags: pic interface, rs232 interface

PC serial port buffer

This is a simple serial port buffer circuit I designed for a friend to speed up his SLIP connection in campus computer network “TRINET” of Helsinki University of Technology. The problem in the network was that the RS232 commections from rooms to terminal server were long and made of bad quality wiring.

The circuit is a simple buffer which adds more driving capacity to PC serial port for the signal to go succesfully from PC computer to terminal server (other direction had no problems). The computer is connected to connector CON1 and the buffered output is available ar CON2. With this circuit the speed of RS232 connection to termial server could be succesfully raised for 9600 bps to 38400 bps.

The circuit is basically a two transistor buffer consistong of transistors Q1 and Q2 which can drive up to 1A current pulses, but the maximum putput current of the circuit is limited by resistor R2. Value R2 was experimentally selected by testing resistor values in range of 22 ohm to 270 ohm and value 140 ohm gave best results (it provides quite good impedance matching to cable used). It is a good idea to use at least 1W resistor in place of R2 to make sure that it does not overheat in output short circuit situation (RS232 devices must withstand that to meet the standard). [...]

Read More Source: http://www.tkk.fi/Misc/Electronics/circuits/rsbuffer.html