RC5 Decoder with µC

by Martin Clausen (mc AT rotgradpsi DOT de)

The SAA3049A from Philips Semiconductor has been discontinued. Therefor arises the need for a equivalent replacement. This page describes a solution using a 8051 MCU.

Table of contents:

Features
Comparison SAA3049A - MCU solution
Parts
Download of Program and Circuit
Similar Projects

Features

Low cost RC5 Decoder employing AT89C1051 or AT89C2051
Low part count
Two modes selectable via pin:
- Low: output of address and data
- High: comparison of given address and output of data
Low voltage operation down to 2.7 volts
Ack signal
Program is freeware for non-commercial use.

Comparison SAA3049A - MCU solution

Parameter	SAA3049A	MCU solution
Vcc	2.5V - 5.5V	2.7V - 6.0V
Icc max. @ 3V	0.7mA	2mA
Xtal	4MHz	12MHz
Iol sink pin	-12mA	-20mA
Iol sink chip	-100mA	-80mA
pullup resistor	external	weak internal, except P1.0 & P1.1 some application may require an additional stronger external pullup
reset circuit	resistor, cap, diode	cap
pinout	SAA3049A	AT89C1051
mode selection	via ack pin circuit	dedicated mode pin Low: output of address and data High: comparison of given address and output of data
address input	non inverted	inverted (closed switch to GND = 1)
IR-code	REC80 or RC5	RC5 only, no code selection pin

Parts

Semiconductors:
1 AT89C1051 or AT89C2051 or any other 8051; see also programming tips

Capacitors:
1 1µF / 25V axial
2 33pF cer
1 100nF cer

Resistors:
2 10k, if pullups for P1.0 and P1.1 are needed

Mechanic:
1 12MHz crystal
1 socket 20 pin

Download of Program and Circuit

rc5decoder.hex MCU program V0; see also programming tips
rc5decoder.gif circuit V1.00
no, I do not give the source code away, email me if you have a problem
ask me for a chip, if you do not have a programmer

Similar Projects

Description	Author
RC5 decoder and transmitter with AT89C2051, including source code, I have received a report, claiming that it has problems with certain signals	Wagner Lipnharski
Universal Infrared Remote Control with AT89C2051, including source code	Lawrence Mazza
RC5 decoder, PIC, in Dutch	Tom Michiels

The part description in schematics is read as follows:
part type + value in exponential form + package description + subpart number in package
for example: C1040805,1 means Capacitor, 100nF, package SMD 0805, first subpart in package

Disclaimer: No warranty at all!
Copyright by Martin Clausen, Germany.
Contact the author: mc AT rotgradpsi DOT de
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