Which microcontroller is best for simple 120-220V control?

I am starting an embedded control project.  This is so simple that
probably any microcontroller will do, but I will first ask the experts
which would really be the best.

Here is the basic spec:

Interface:
  A few switches
  Drive a relay to control one 120-220VAC 500W device

Microcontroller:
  Real time timer
  Battery backup or nonvolatile memory
        for power failure
  Small, cheap

Development Environment:
  C compiler
  Simple development kit
  I am an electrical engineer with C++ experience

Please let me know your recommendation of microcontroller.

I would suggest an AVR Family Member since it's

- cheap
- there are devices in PDIP housings, ideal for prototype
- there is a freeware c compiler (afair also a c++ environment - but do 
you realy need c++ on a microcontroller ?) and some commercial c, pascal 
  or basic compiler
- the devices have some cmos ram, eeprom, flash eprom; some have a 
secondary x-tal for clock applications.

have a look on the atmel avr application notes.

hth.

hans

     At this point in time, I would look hard at the Texas Instruments
MSP430 for new designs where compatibility with previous software is
not an issue.  These chips run on extremely low power.  While the
advantage of this may appear to only be in battery operated products,
it has a number of advantages for other purposes as well.  For
example, you could retain memory for a long time with a low leakage
capacitor.  Also, low power means low interference so high precision
analog peripherals are available on-chip (16 bit A/D is available).
Also, low power means low heat generation so on-chip temperature
sensors are available.  

On 20 Oct 2005 00:09:38 -0700, google@voom.net wrote:

>I am starting an embedded control project.  This is so simple that
>probably any microcontroller will do, but I will first ask the experts
>which would really be the best.

>     At this point in time, I would look hard at the Texas Instruments
> MSP430 for new designs where compatibility with previous software is
> not an issue.  These chips run on extremely low power.  While the
> advantage of this may appear to only be in battery operated products,
> it has a number of advantages for other purposes as well.  For

I second that. Beautiful architecture.

Perhaps they could power it directly by mains, using a capacitor... without 
transformer...

(yes, this is dangerous to work with during development!)

Hello Gary,

>      At this point in time, I would look hard at the Texas Instruments
> MSP430 for new designs where compatibility with previous software is
> not an issue.  These chips run on extremely low power.  While the
> advantage of this may appear to only be in battery operated products,
> it has a number of advantages for other purposes as well.  For
> example, you could retain memory for a long time with a low leakage
> capacitor.  Also, low power means low interference so high precision
> analog peripherals are available on-chip (16 bit A/D is available).
> Also, low power means low heat generation so on-chip temperature
> sensors are available.  
> 

My favorite as well. However, despite a new round of releases they seem 
to be on the pricey side and that has so far barred them from any of my 
designs. I am still holding out for that bare-bones low pin count MSP430 
in the 30c category.

Regards, Joerg

http://www.analogconsultants.com

On Thu, 20 Oct 2005 14:25:54 +0200, Hans M&#4294967295;ller <heintest@web.de>
wrote:

>I would suggest an AVR Family Member since it's
>
>- cheap
>- there are devices in PDIP housings, ideal for prototype
>- there is a freeware c compiler (afair also a c++ environment - but do 
>you realy need c++ on a microcontroller ?) and some commercial c, pascal 
>  or basic compiler
>- the devices have some cmos ram, eeprom, flash eprom; some have a 
>secondary x-tal for clock applications.
>
>have a look on the atmel avr application notes.
>
>hth.
>
>hans

The other good thing about the AVR is that AVR studio simulator / ISP
programmer /  JTAG debugger are available as a free download from
Atmel.  Imagecraft make a very cost effective compiler that is very
good combination with AVR achitecture.

You may need to watch choose low power variants and consider using low
frequency operation for the type of power source you suggested.

regards,
Johnny.

I agree. The MSP430 is nice... but my only reservation for a battery backed 
unit is that there is no brownout feature on the MSP430. As a result of the 
changeover and subsequent draining of the backup battery you may, (and I 
know first hand knowledge of this), suffer from a micro lockup. Your main 
power comes back online, only for your processor lock.  Add an external 
reset/brownout circuit and you'll be on to a winner.! :-)

Jim
www.picmodules.com

"Hans M&#4294967295;ller" <heintest@web.de> skrev i meddelandet
news:43578cd3$0$12662$9b4e6d93@newsread4.arcor-online.net...
>I would suggest an AVR Family Member since it's
>
> - cheap
> - there are devices in PDIP housings, ideal for prototype
> - there is a freeware c compiler (afair also a c++ environment - but do
> you realy need c++ on a microcontroller ?) and some commercial c, pascal
> or basic compiler
> - the devices have some cmos ram, eeprom, flash eprom; some have a
> secondary x-tal for clock applications.
>
> have a look on the atmel avr application notes.
>
> hth.
>
> hans

Won't disagree with the AVR recommendation ;-)

Probably you should be able to do a nice job with the ATmega48/88/168.

Tools for the AVR:
STK500 development board (< $100). With this you can program your part.
AVR Studio now supports GNU C compilers (WinAVR)
    Downloadable from www.avrfreaks.net
Otherwise there are free versions (code limited) from
IAR : IAR will support Embedded C++
Imagecraft
etc.
A JTAGICE Mk II will allow you to program and debug.




-- 
Best Regards,
Ulf Samuelsson
This is intended to be my personal opinion which may,
or may bot be shared by my employer Atmel Nordic AB

"Jim" <tech@picmodules.com> schrieb im Newsbeitrag
news:nw96f.1280$Jl3.495@newsfe4-gui.ntli.net...
>
> I agree. The MSP430 is nice... but my only reservation for a battery
backed
> unit is that there is no brownout feature on the MSP430. As a result of
the
> changeover and subsequent draining of the backup battery you may, (and I
> know first hand knowledge of this), suffer from a micro lockup. Your main
> power comes back online, only for your processor lock.  Add an external
> reset/brownout circuit and you'll be on to a winner.! :-)
>
> Jim
> www.picmodules.com
>
>

All MSP430 devices but the older '11x1 and '149 have the brownout feature.

See e.g.
http://focus.ti.com/lit/ds/symlink/msp430f1232.pdf

http://focus.ti.com/lit/ds/symlink/msp430f2131.pdf

http://focus.ti.com/lit/ds/symlink/msp430f169.pdf


MIKE

> All MSP430 devices but the older '11x1 and '149 have the brownout feature.
>

Oooops !

I used the 149. I should have said that in my post

Sorry for the mis-information.
:-)

Jim
www.picmodules.com