View Single Post
Old 11-16-2011, 09:05 PM   #629 (permalink)
Master EcoModder
Join Date: Apr 2009
Location: Charlton MA, USA
Posts: 463

EVVette - '71 Chevy Corvette Coupe
Thanks: 31
Thanked 183 Times in 94 Posts
Originally Posted by CollinK View Post
So... I'd like input on this:

I'm thinking of switching to dsPIC33 chips before I finalize a PCB design. This chip is newer than the dsPIC30 chips and programming wise uses the same instructions and everything. dsPIC30 chips are not recommended for new designs anymore. However, there are some points to consider:

1. Every dsPIC33 chip is 3.3v. There are no exceptions. So this would require a 3.3v regulator on top of the 5v regulator already in use. And I can't just get rid of the 5v regulator because other things need it. This is easy, though, I can just use a 3.3v regulator off of the 5V source.
2. dsPIC33 chips can only sink or source very low currents (4ma) as opposed to the 25ma possible with dsPIC30 chips. This means one would need a bunch of transistors. Granted, I probably should plan on that anyway.
3. dsPIC33 chips do not come in DIP40 packages (which is what the current layouts all use). You must do 28 pin if you hope for it to be through hole. Otherwise it jumps up to 44 pin QFN.
4. dsPIC33 chips have no EEPROM
5. They do, however, add other nice stuff like ECAN, programmable PLL, more interrupts, more timers, 12 bit ADC, DMA.

I'm really strongly looking at using 44 pin QFN for the dsPIC chip. It could be the only surface mount chip required. I don't think it will be too terrible to solder and boards could be sold with the dsPIC already soldered on for those who don't feel adventurous. I could use dip28 chips but I would almost certainly end up needing two of them.
I would have to vote to stay with the dsPIC 30 and stay away from the 33.

While I think the 33 would be more suited towards a comercial product, I think 3.3v logic is more often then not out of the expertise of the hobbiest.

I would not mind 3.3v logic, But my vote is if your going with 3.3V micro, change as much as you can to use 3.3v logic directly instead of shifting signals all over.

__________________ - 1971 Corvette Coupe Conversion to all Electric! - Machining, CNC, Robotics and Electronics.

You can download RTD Explorer for the Cougar controllers at
  Reply With Quote