Does anybody make a micro with 3 DACs

I've not seen any DACs on logic devices that are worth a damn. For some reason they can make ADCs but not DACs. Sixteen bits really is pushing it.

connect 3 or more sample/hold amplifiers to one dac.

I know that the 68HC11F (old part) had C/2C ladders instead of R/2R -- I wonder if that's the case for all of them, and the resistors just can't be done?

Seems like you could make a dynamic DAC, put a C/2C ladder into a sample & hold, and keep updating it -- but I dunno.

Sjouke Burry schrieb:

Hello,

this would waste PCB space in comparison with the alternative of using a quad DAC in a small package.

Bye

Analog Devices ADUC7000 series have 12 bit DACS, up to at least 4 in a chip.

Unfortunately, it looks like it is bigger than the micro plus DAC chip method but it certainly does have the number of DACs. I may still go with it because it has enough performance that I may be able to bring other functions on board.

Thanks

The ADUC7021 is pretty small - 6mm LFCSP. There seems to be a 5mm BGA package too but that seems like a lot of work.

It has some other useful analog functions too: a good 12 bit 1Msps ADC, comparator, reference, temp sensor. And a simple PLA!

Unless you use a Cyrpess PSoC as the micro and employ its S/C filter blocks in a somewhat unorthodox manner. I have never done it but in case someone is interested this seems to explain it:

Unfortunately, unless I misread it, the 7021 only pins out 2 DACs

I don't think you'll get an honest 12bits and certainly not 16, out of a PSoC. Cool part, though.

Have you looked at the Atmel XMega series ?

Yes, sorry, you're right. Try the 7023 then.

Cheaper too, being a "new product", with more pinned-out peripherals.

Thanks for making me look!

Do they make any with more than one DAC?

If I was going to go with a different CPU core, I'd most likely go with the ARM. It seems to be the one that has become the most popular.

Right now I am using a micro with two DACs from Scilabs. It is very fast and has the advantages of the 8051 instruction set. 100MIPs of flinging bytes around can get things done in a hurry.

The ATxmega64A1, 128A1, 192A1, 256A1 and 384A1 all have 4 channel 12 bit DACs.

Yes you are quite right. Somehow from the web site I got the impression that it was one DAC per micro.

I am now about to read up on the Atmel and the AD parts.

Read carefully about the AD part. Especially about the PLA capabilities. I was caught there. Don't remember exactly what it was but I think I couldn't use it to directly trigger some AD or DA operation as could have been expected. (was doing a multibit SD ADC)

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I want to pump the ADC at lets say CLOCK/2060 I think I can do this.

It looks like the ADC and DAC interrupt (the same one) will need to be coded in assembly. Basically, I need to read the ADC and write the DACs in a tight section of code that sort of looks like this:

AdcValue =3D ADC0

DAC0 =3D DcValue + Scale0 * InterpolateTable(Table1,Index1)

Temp1 =3D InterplateTable(Table2,Index2) Temp2 =3D InterplateTable(Table3,Index2)

DAC1 =3D DC + Temp1 * Scale1 + Temp2 * Scale2 DAC1 =3D DC + Temp1 * Scale3 + Temp2 * Scale4

Index1 =3D Index1 + Step1 Index2 =3D Index2 + Step2

UpdateScales(AdcValue)

The DACs always are based on the previous ADC values. The math to work out the scale factors will be spread over many ADC read steps. UpdateScales may be in C but even it looks like it may have to be in assembly to get it done fast enough. I will be counting machine cycles.