Hi guys,

I am newbie (in my late thirties!!) with background in Mech Eng. I want more than one analog voltage outputs from embed. Follwing are two questions:

1. What is the maximum number of analog voltage outputs I can get from embed?

2. How to obtain more than one analog volatge output from the embed. I want DIFFERENT voltage signals at outputs.

I shall be very grateful for help.

Many thanks.

Jawaid

Hi Jawaid, and welcome.

As far as I know, the datasheet only describes a single analog out.

If that's not enough, you can use a PWM (there's several of these), with a filter. (more ripple, but useable).

Hope this clarify. :-)

/ Lerche

Welcome, Jawaid.

Another possibility would be to use a DAC (Digital to Analog Converter) with an I2C interface. That would allow you to control multiple output voltages using just two pins of the mbed. The MAX518BCPA+ comes in an easy-to-use Dual In-line package. It has two analog outputs, and you can connect up to four of them to a single mbed.

I don't think there is an mbed library for this device yet, but it would not take long to create one.

National also has a nice series of DAC's with an spi interface with rail-rail outputs. They have packages with 1, 2, 4 and 8 outputs per chip and resolutions of 8, 10 and 12 bits.

http://www.national.com/analog/adc/low_power_dac

The outputs also include a relatively high current output buffer.

Those look nice DACs, Mike, but it seems that none are available in DIP packaging, which I suspect a  new experimenter would need.

Oops - your right. I should pay more attention to that. I used those parts in a past project, but never on a breadboard only on prototype pcb's.

Breadboarding seems to be getting harder. Many new parts are not available in Dip packaging at all. To use new parts on a breadboard you can use adapter boards similar to these:

http://www.sparkfun.com/commerce/product_info.php?products_id=494

Or these:

http://www.nkcelectronics.com/adapter.html

It's one more strep, but it is nice to be able to use newer parts that are only available in surface mount. I try to keep a variety of these types of adapters on hand.

Yes, adapters like that are life-savers for breadboard addicts.

I soldered my first-ever SMT chip (a TMP175) onto a similar adapter last night. Slightly scary if you are 62, can't see without spectacles, and have 10 thumbs, but I did ok :)

Thanks for the links. The nkc electonics boards look great value, and they ship to the UK where I am based using inexpensive airmail.