Differential A/D converter

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Is there a list of AVRs that have a differential A/D? I currently have a sensor using the ATTINY24, but the I2C interface is giving me grief. I was wanting to try a part with the higher end TWI than the USI. I'm concerned that the lack of slew rate limiting on outputs and input filters is causing my master to go into slave mode. (Master I2C is on ARM device)

Thanks,

Mike.

official AVR Consultant
www.veruslogic.com

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Many new devices in the AVR mega range have differential inputs, but limited to two or four pins (ADC0+ADC1, ADC2+ADC3, IIRC), and also limited gains (x1, x10 and x200, IIRC). I suggest reading some datasheet like ATmega164P or similar.

Xmega offer greater results in this area, but they are a totally different world. Probably they still remain in a totally different world or even universe.

Guillem.
"Common sense is the least common of the senses" Anonymous.

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Your question is on a differential A/D converter, but your problem is with the TWI interface.....

You rwould have to check the datasheets of a number of ATMEl devices to see if it has or hasn't got a differentiel A/D converter. A large number of them has, so there is choise enough.

If I remeber correctly all the Mega parts have a full blown TWI interface. The tiny's all have USI. The arm is thus basically running in multi master mode and thus there are multiple masters on the bus that cause this to happen. That is also what is specified in hte I2C specification. That in multi master mode the master is also capable of at least detecting that the bus is bussy and thus atleast needs to be listening to the BUS. If the ARM is the only master then you shoudl change the code to reflect this and thus master is only master and all other devices act only as a slave and thus only talk when they are asked to.

regards

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The ARM part is coded for only a master, as are the tiny's coded only as slaves. However, the ARM controller automatically switches to slave when it sees a start condition. It doesn't have a mode bit to force to master or slave mode. I'm capturing that event, and it occurs in 10 minutes or 10 hours. It seems to be transient related.

I was wanting to try out the TWI operation as compared to the USI. But my sensor requires a differential A/D input. Not all low cost megas have a differential A/D. The Atmel web site simply indicates A/D and does not differentiate between single ended and differential.

official AVR Consultant
www.veruslogic.com

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the mega48/88/168 do nnot have differential AD

the mega16 has ( probably the mega8 & mega32 will then also have it.

unfortnately the tiny48 only has TWI and not differential ADC that would be a nice one.

so you could check out the mega16 or even better would be to get a grip on the transient. This becaues it might not only give you a problem with the ARM, but also might cause the other periphirals to give strange behaviour.

regards