Looking for that perfect microcontroller

Thread Starter

sjkim0329

Joined Oct 19, 2008
12
Hi, guys

I'm just getting to learn about microcontrollers recently.
I ran into a couple problems choosing a controller.
I'm asking for your help and suggestions from your knowledge and experience.

Two cases,
I need to read two analog sensors at 100Hz, average about 5 samples, output serial status message.

I need to read in 8 sensors at 16 bit resolution at 1kHz, Measure state at 100Hz with a Kalman filter, control 3 actuators with a PWM, update state info over CAN.

I had Luminary Micro LM3S8961 in mind for 2nd case, but what do you guys think?

Thanks for your time,
 

Thread Starter

sjkim0329

Joined Oct 19, 2008
12
Yes, I did try to find something at PIC. Other than going through all the data sheet and try to find out which controller works the best, is there any other way to find one?
Because there are a lot of controllers out there.
Thanks.
 

hgmjr

Joined Jan 28, 2005
9,029
Don't know about the PIC but the AVR only has a 12-bit A-to-D converter. Is it possible for you to get away with 12 bits of resolution?

hgmjr
 

Thread Starter

sjkim0329

Joined Oct 19, 2008
12
I could try. So AVR can be done with 12 bit of revolution?
if it has to be 16 bit. Do you think PIC would have it tho?
 

hgmjr

Joined Jan 28, 2005
9,029
I took a second look at the AVR device list and while there is an AVR with a 12-bit A-to-D, the device is not in a through-hole package. The through-hole device only has a 10-bit A-to-D.

hgmjr
 

Thread Starter

sjkim0329

Joined Oct 19, 2008
12
I wanted to make sure. I'm looking for 2 different controllers.
Not both cases have to be working for one.
I think you might have misunderstood it.
 

hgmjr

Joined Jan 28, 2005
9,029
I was thinking that the second case was the more stringent of the two cases. My thought was that the solution for the second case would be a shoe-in for the first case.

hgmjr
 

nanovate

Joined May 7, 2007
665
The Luminary Micro stuff is only 10-bits.

PIC18 might be an option but it is only 10MIPS and you need to implement a Kalman filter
PIC24 is another option -- 40MIPS and 12-bit 500kSPS 10-ch
student compilers (certain optimzations reduced)

AVR XMEGA
dual 2MSPS 12-bit ADC (16-ch)
32MIPS
DMA
unlimited free compiler

Silabs
25 MIPS C0805F064 has dual 1MSPS 16-bit ADC
DMA
limited free compiler
 

AlexR

Joined Jan 16, 2008
735
Both AVR and PIC limit their DtoA to 10 or 12 bits (depending on the part). If you really need 16 bits you have to go to an external AtoD chip but that leads to the question do you really need 16 bit, that's 65 thousand voltage steps! Is you reference voltage stable enough to get meaningful results from a 16 bit conversion or is this a case of the more bits the better the specs look.
 
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