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which one is the best for me ?

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Junior Member level 2
Jan 14, 2006
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hello everyone
i just wanna started my project using microcontroller together with PIR sensor (motion) and some solid state relay ( it can trigger 220 V AC with 5 V DC) for controlling the lamp, turn on , turn off, and if possible a dimmer feature will be added , this my first time dealing with the microcontrollers, i wanna ask which micro will be the best for me ? 8051, or AVR ? which one has better PWM instruction ?

i don't know the AVR. but the 8051 has noe PWM instructions.
i know that the PIC has. try any PIC micro controllers. may the 16f84 usefull fo u.
the advantages op pic that it is easy to learn. and easy to get a programmer ( u can build it easy) also in curcuit debugger also easy to build.
good luck



PWM is not done through instructions, it is done through PWM timers. There are 8051 derivatives, AVRs and PICs that can do that. Your challenge is in the hardware interface. Get a microcontroller kit that you know one of your friends is familiar with. Your computational features can be done with any microcontroller running at 1 kHz.


bobsanjose said:
PWM is not done through instructions, it is done through PWM timers.
Well, not exactly. Actually, there are no uC instructions to handle PWM in software, but selecting a controller with a hardware PWM circuits may be an overkill for some applications. For the power control applications with a few PWM channels, it is very easy to make very accurate PWMs in software. For a 50 or 60 Hz mains this kind of software is not a challenge at all. uCs with many hardware PWMs are much more expensive than those without.
As I said, it all depends on the application and the programmer wheteher to take HW or SW approach.
Regards, yego


I started with different 8051 mainly from philips, atmel, cygnal finally ended up using AVR.

My main reason for using AVR has been its ISP (in-circuit programming capabilities) and the support available from ATMEL. I have been able to make 3 programmers (1 parallel and 2 serial) myself. The Assembler is available from ATMEL and is verys nice. Wheras cygnal also offers ISP for 8051 but I am not able to get any information about simple parallel port programmers. I have to use cygnal hardware.

Another thing good about AVR over 8051 is that configuration of I/O is much easier. For example if you configure the Port pin as RS232 (Rxd Txd) then hardware configuration is done automatically.

Further the last good thing about AVR is that you can get powerfull µC in DIL package which is easier to solder on universal PCB.


Added after 12 minutes:


Sorry I missed out the PWM part. I have used hardware PWM before using philips 8051 derivative.

Whether to use hardware or software PWM depends on resources available and your aim. If I am a student I would use software PWM to learn and demonstrate its implementation(provided I am not behind schedule). However If I am making a complex commercial product using interupts, RS232 etc I would rather use hardware PWM.


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