Microcontroller Family Selection Guide

On Tue, 06 Nov 2007 10:33:59 -0800, I said, "Pick a card, any card" and Eric instead replied:

Go here:

Create an account and set up your page. From the Babel-like comments in the responses here, your best option is a matrix with comments allowed.

-- Ray

At risk of piling on, I think you have an error in your description of the Arm Cortex M3. You say "all instructions are 16 bit instructions", which I don't think is correct. I believe they are all Thumb instructions including both the original Thumb and the Thumb2 instructions, but some of the Thumb2 instructions are 32 bit. I believe this is organized with a 16 bit "prefix" and a 16 bit instruction similar to some of the x86 instructions.

Please correct me if *I* am wrong... :^)

That's correct (you for instance in Section 1.2 of DDI0338G).

Laurent

I remember your post. Thanks! It was around the time I decided to revisit some 32-bit fp-div code I'd written in 2004 and around the time that Wilco pressed me on some issues I'd not handled well enough.

The final version I have has been posted up to the yahoo msp430 forum in the files section and achieves 255 cycles (with call/return included) for an FP 32-bit division on the MSP430. (+/-1 cycle.) About 2.4X.

It is free for anyone's use and if interested, you can siphon it also at:

There is a somewhat slower, but also smaller version at:

I'm just reminding folks to keep in mind that not every library routine used by every compiler vendor across families of cpus are comparably optimal -- some library routines are much worse than others and at least a part of whether or not they are better will depend a little on just how valuable and competitive the marketplace is.

So keep it in mind when examining cycle counts. The MSP430 may seem like a 620 cycle fp divide situation or it might look like 255 cycles, depending. But it is the same cpu, either way, despite the 2.4X apparent difference.

Jon

Are they going to have any DIP PIC32's? Microchip is normally very friendly to DIP packages so I hope so. Of course we'd have to clock it down to use it in a proto board.

I didn't know about the spider thing. I only looked at the RS08 in the early days after it was announced.

Are you saying CodeWarrior's C compiler for RS08 and HC08 is free and has no size restrictions? I didn't know that and it would be very important if this is the case.

Now why don't they make a reasonably strong hc08 in a DIP? They lost a lot of students and hobbiests in the early days of migrating from hc05 to hc08 because of this lack

certainly a good thing, especially if the C compiler is free without strings.

But it needs a good cross-section of on-chip peripherals in order to be good for students. If it's too weak there won't be many good lessons there. That's why most Dev boards have strong processors in a given family.

I understand the convenice and low price of the USB dongles but I'm a little concerned about this trend. I think it's important for students to mess with chips, wires, and proto boards. But the USB dongles that have docking boards can fill that gap.

A little early for me to jump on these, but I really loved the PIC24, aside from it's somewhat high current demand.

They just scared me about being in and out of bankruptcy over the years.

This is a difficult chip to teach with because of the learning curve. Maybe it's the wave of the future? I'll wait longer before deciding on that.

Eric

Unlikely, with the pin counts of the first releases. (maybe later)

If you want a Plug-able high end core, the best is probably the Z16F, as that does have a PLCC package option. [has 32.32->64 opcodes]

My understanding is the RS08 compiler is free for all RS08 (since it's a

16K Max core, with only 1K shipping), the HC08 compiler IIRC is free to 16K? and the Coldfire V1 is free to 128K?

DIP is trailing edge technology. Silabs have one DIP20 offering, and I see Philips and Atmel have PLCC32 packages as their 'plugable' offering of what are otherwise all TSOP or QFP 'volume' devices.

Then there are always 'carrier modules'...

Depends on the depth of the course. The RS08 could reach down into high schools, and introductory courses. If the tools are easy, it can also be used to show students what's involved in using more than one core - since it is quite likely students will work on cores NOT the same as they are first taught, showing them the jump is a good thing :)

Freescale do seem to be slow releasing the 'next' RS08 members. The Vreg and Osc details are impressive, so more variants would make users happier.

Yes, building something that works, is cornerstone to embedded design

Exactly. 0.1" headers can serve that task. Also the Silabs USB splits on a PCB edge connector, so add one of those and you have the same USB debug.

True, but their documentation is quite good, as are the tools. Their cores are also designed from the ground-up as Microcontrollers, so avoid some of the knee/bottlenecks in other cores.

It is certainly different, but that makes it interesting :)

-jg

I updated my paper with some of the corrections you folks pointed out. I appreciate your help. I did not info on new families aside from my "first thoughts" on the PIC32.

As time allows I want to do another paper on development tools for newbies. The main problems newbies have is to determine what type of board(s) to buy, what type of software to install, and how to program and debug the devices. The answers to these questions vary a lot by family so that paper could line up with this one to some extent.

I'm not going to start a Wiki myself but anyone can use my material if they want to make one, and I'll try to help by adding new content also.

Eric Microcontroller Family Selection Guide:

You may want to add that the AVR can, if running from the internal R/C oscillator start from power down is less than 1 us. Significantly better than the 7 us, quoted for the MSP430.

Also, the AVR can normally be run at a lower voltage than the MSP430 which affects the power consumption. The AVR can be programmed with Vcc downto 1,8V, some downto 1.62 even if that is not reflected in the official datasheet.

Think you need to dig into the Brown-Out stuff as well. Some of the MSP parts are quite weak here.

>

--
Best Regards,
Ulf Samuelsson
This is intended to be my personal opinion which may,
or may not be shared by my employer Atmel Nordic AB

meddelandetnews: snipped-for-privacy@v65g2000hsc.googlegroups.com...> > >> I wrote up some of my thoughts about various microcontroller families.

The newest msp430's are better in a number of categories over their predecessors, but I'm guessing the Picopower devices may indeed be better in certain situations. I went to the Picopower seminar and I want to start working with these soon.

I'll be working on the tools paper next. Does Atmel or any other company mentioned in my paper have special discounts for colleges or students? Educators usually have tight budgets. I work with professors sometimes so I know that price often drives their board and tool choices.

Eric

You want to have your professors look at

--
Best Regards,
Ulf Samuelsson
This is intended to be my personal opinion which may,
or may not be shared by my employer Atmel Nordic AB

...

Thus validating Eric's claim:

If I was trying to implement a Harvard architecture, and managed to build something that was von Neumann, I must have messed up bad, no?

mlp