Low Power Cortex M?

Maybe you could give some indications what your power budget is for a single chip. At least allowed power/MIPS for the core. Possibly some indication of allowed power for all the extras.

Most (all?) Cortex-M3 are quite nice when it comes to power/MIPS since the manufacturer buys the processor core as a macro cell and the macro cell for a given technology should have a quite fixed power consumption.

ARM specifies figures down to 0.085 mW/MHz on the TSMC 0.13G process. I think the 0.18G process will consume 0.19mW/MHz. The ARM7TDMI on the 0.18G process is around 0.28mW/MHz.

Another thing is if you are going to use a common oscillator, or if each processor will have their own crystal. Processors will normally consume less power when receiving a nice square wave clock signal.

Unless you are forced to use Cortex-M3, you may also look at the ARM996HS which has asynchronous clocking and have a core specified to only 0.045 mW/MHz.

But in the end, the peripherials may be the big difference, since they can stand for a significant percentage of the total consumption and are what differs between the manufacturers.

I haven't had the time to read through all the information from the link Tamir posted, but did the guy you got in contact with inform you exactly what Energy Micro did better than other Cortex-M3 manufacturers?

Maybe you could give some indications what your power budget is for a single chip. At least allowed power/MIPS for the core. Possibly some indication of allowed power for all the extras.

Most (all?) Cortex-M3 are quite nice when it comes to power/MIPS since the manufacturer buys the processor core as a macro cell and the macro cell for a given technology should have a quite fixed power consumption.

ARM specifies figures down to 0.085 mW/MHz on the TSMC 0.13G process. I think the 0.18G process will consume 0.19mW/MHz. The ARM7TDMI on the 0.18G process is around 0.28mW/MHz.

Another thing is if you are going to use a common oscillator, or if each processor will have their own crystal. Processors will normally consume less power when receiving a nice square wave clock signal.

Unless you are forced to use Cortex-M3, you may also look at the ARM996HS which has asynchronous clocking and have a core specified to only 0.045 mW/MHz.

But in the end, the peripherials may be the big difference, since they can stand for a significant percentage of the total consumption and are what differs between the manufacturers.

I haven't had the time to read through all the information from the link Tamir posted, but did the guy you got in contact with inform you exactly what Energy Micro did better than other Cortex-M3 manufacturers?

Battery Size is TBD dependent upon the electronics, but so far the calculated budget allows for a 32 hours on a 2800mA/H LiIon: in what I think is 'worst case'. But of course simulation versus the real thing can be wrong.

Per is right about the external peripherals' power usage. Those have been addressed and mitigated.

A purpose behind knowing a low-power Cortex is an evaluation of the actual MIPS truly needed to accomplish the same goal as a 'fast' 8051.

Like cars, you'll find that they size the gas tank to ensure at least 300 miles between refueling to prevent the owner from thinking it is a gas hog, or get annoyed by constantly going to the gas station.

The same will happen on this project. I don't want the customer spending 'too much time' charging the unit.

Although I said before, that 24 hour mark is for the heavy user who uses it for 8+ hours at a time, while the typical user would use it for about an hour at a time.

Another aspect of the project is to convert the discrete CPUs (uCs) into an FPGA fabric. Thus the code-monkey-book shall be followed to make that "C" to VHDL transition... then I'll clock it down to reach for optimal battery life while still maintaining performance.

--Cpt. Vince Foster
2nd Cannon Place
Fort Marcy Park, VA

MCB1000 ?

No such thing listed at http://www.keil.com/boards/

"2800mA/H"

I expect you meant 2800mAh @ 3.6V since you need voltage*current*time to get energy, and that you are talking about a one-cell battery. Say 8W usable after losses from a DC/DC.

Counting 12 hours operation and a 90% power reduction for the idle hours, that would give about 0.6W when active and 0.06W in idle. Assuming 50% for the cores to process instructions, and 50% for internal modules (DMA, UART etc) and external logic, you would have 0.3W for instruction processing.

If the claim of 0.09mW/MHz is true for the 0.13G process, your 0.3W would then be enough for 300/0.09 [MHz] = 3.3 GHz or 33 processors running at 100MHz.

Processors using the 0.18G process would give you 300/0.19 [MHz] = 1.6 GHz.

I really must have computed something wrong, but the figures sounds quite large ;)

Just a footnote, but I normally add a *0.5 as safety margin when doing initial calculations, to cover ageing of batteries, unknown late-stage requirement changes etc and still have a bit of extra engineering margin. Better to be able to reduce the battery size after measuring on prototypes than to have to figure out how to fit a larger battery pack in a too small box after the tools for making the box have already been produced.

Absolutely!!!

Follows the general "make it work first; optimise later" approach.

Please check Cypress PSCO5 (available only on january)

With some effort you can increase the power of these ones:

www.ehow.com/how_4791464_tone-flabby-arms.html

Really - at last?!

See: www.8052.com/.../165761

Most (all?) Cortex-M3 are quite nice when it comes to power/MIPS since the manufacturer buys the processor core as a macro cell and the macro cell for a given technology should have a quite fixed power consumption.

Err ... I don't think this generalization holds.

We were looking at Cortex-M3s before Atmel started offering theirs, and there was a factor of _10_ between the Cortex M3 of one of their competitors, and an ARM7 from Atmel, at a similar MIPS/memory/peripheral point. (The power dissipation for the Cortex M3 was about 250 mW according to the datasheet, for the ARM7 30 mW.).

Some manufacturers are better at peripherals and processes than others. Don't assume that just because it's a Cortex M3 chip, it will be a power-saving wonder. Read the datasheet first.