Investigation into PSU noise. Corsair CX600.

[cyberfish]

I generally work with $1-$4.50 MCUs, partly for that reason.

The higher end stuff isn't really that much more expensive, but they are harder to work with if you don't design your own PCBs, because they are all surface mount.

My personal favourite is the STM32 series. 32-bit ARM Cortex-M4F core at 168MHz, and a crapload of peripherals (something like 17 timers, and 3x2.4Msps ADCs that can be interleaved as 1x7.2Msps ADC with some limitations, and up to 1MBytes RAM).

For around $10-$15: http://www.digikey.com/product-sear...s/embedded-microcontrollers/2556109?k=stm32f4

For mass produced products the few bucks would matter, but for personal or low volume projects I've switched more or less exclusively to 32-bit MCUs.

If you don't need some things like big memory and USB HighSpeed support, I think you'd be able to find Cortex-M3 chips for ~$5.

For some of my projects that need a USB interface, the USB support in STM32 makes it worth it by itself, because if I used an AVR/PIC, I would need an FTDI chip for USB interfacing, and that would be the few bucks difference already.

 

[Bobnova]

I'll have to look into those, I have been designing my own boards so that's not an issue.

There are a number of AVRs with built in USB, some of 'em have even been set up to use the Arduino IDE.
They don't have anywhere near that processing power though.

 

[cyberfish]

Ah I didn't know there are AVR USBs. For the longest time that was the biggest difference between PICs and AVRs. AVRS are fast and simple and lack peripherals, and PICs are the opposite.

Oh and by the way, ADCs getting confused with high speed signals could be due to aliasing, if the input signal has frequencies above the Nyquist frequency (sampling rate / 2). So input signals need to be low pass filtered to the Nyquist frequency electrically before being fed to the ADC.

 

[cyberfish]

Got a brand new CX600 from cross-shipping, and it's exactly the same.

I won't RMA it again since I know it won't help. I'll shelf it until next next weekend, when I'm back in Canada with my trusty scope to do more investigation.