Hello, all:

I'm starting work on a data logger project for my SBC2 and I'm looking for recommendations for a 6502-friendly A/D chip that's still available at a reasonable price.

I've been paging through my old hardware books and my storehouse of BYTE magazines but a lot of projects they contain use chips that are either no longer made or are hard to find.

So before I spend lots of time going through Maxim's or Analog Devices' Web sites, I'm appealing to the 6502.org community for suggestions and recommendations? Maybe a solution someone has used recently.

In general, I'm looking for an 8-input A/D that's capable of an 0-5v measurement range.

Any suggestions are appreciated. Thanks.

Rich

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Rich Cini
Build Master and maintainer of the Altair32 Emulation project
http://cini.classiccmp.org
http://altair32.classiccmp.org

ADC0804 by Texas Instruments is a good bet. It has either 6 or 8 analog channels and an 8 bit output. The arcade industry seemed to use it a LOT and its the most common AD that I know of.

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"My biggest dream in life? Building black plywood Habitrails"

Hi Rich,

You may want to consider something like the LTC1298 from Linear Technology:

http://www.linear.com/prod/datasheet.html?datasheet=293

This is a 12-bit ADC that has a software-selectable 2-channel mux. It uses a three-wire interface to your 65C22. It is readily available in 8-DIP from suppliers like Digi-Key (LTC1298CN8-ND). If you need more than two channels, you can use your ADC in conjunction with analog switch like the 4066.

Regards,
Mike

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- Mike Naberezny (mike@naberezny.com) http://6502.org

I've been using the Maxim MAX153, and before that, the ADC0820 which is almost the same thing but not quite as fast. These are half-flash converters. I believe you can buy small quantities of parts directly from Maxim now with a credit card on their website, www.maxim-ic.com , and I noticed the ADC0820 is available from Jameco for $3.19. One of the modes of these two ICs allows you to read it as if it were memory. If you're only going 1MHz you might be able to put the MAX153 directly on the bus and read it as if it were actual memory. The conversion is started by selecting the IC, and by the end of the read cycle, the data's ready. An LDA ADC0820 would do it. The programming doesn't get much easier than that! With its own built-in track-and-hold circuit, full accuracy is maintained to over 100kHz input frequency.

You can see my hook-up at http://www.6502.org/users/garth/project ... chematic=8 . I did use a 65c22 port for the 8 data bits, plus one bit of another for the enable. When the A/D is not selected, the port is unaffected by its presence and is available for other things. The picture of my notebook page is not the clearest, so E-mail me if there's something you can't read. The speed and simplicity make it practical for digital recording.

If you don't need the speed, the serial ones take less room and are easier to hook up. There are some 8-pin A/D's like the ADC0831 and ADC0832 (2-channel) which have been around for a long time and are probably available from several manufacturers. The same-family '0834 and '0838 are 4- and 8-channel and come in 14- and 20-pin DIPs. The '0832, '0834, and '0838 can also be configured for differential inputs.