CPU not MPU/MCU

[Oznog]

What kind of Mhz/Mips do they offer?

I think PIC18F are like 1Mhz = 1/4 MIP

No, PIC18F are 10MIPs, and that's 8-bit RISC. No point in speaking ill of it, 18F can do quite excellent things when they fit the job. Better choice than a more powerful processor for a million things.

PIC33F is 40MIPs and 16-bit, with a DSP core.

 

[Nigel Goodwin]

No, PIC18F are 10MIPs

I think you've missed his point

That's exactly what he said - 1/4MIPs per 1MHz clock frequency.

 

[AtomSoft]

yeah I LOVE PICS dont worry i wasnt trying to speak it down...

1/4 mip per mhz

40 Mhz PIC = 10MIPS

 

[Oznog]

yeah I LOVE PICS dont worry i wasnt trying to speak it down...

1/4 mip per mhz

40 Mhz PIC = 10MIPS

Ah. Yes, "sort of" true. Actually the later models of PICs all have PLLs, so internal frequency is separate from the xtal freq. So the "mhz" part isn't even important. I could take a 1MHz xtal and use the PLL multiplier to get 40MHz internal freq and 10MIPs. Since you never actually see the 40MHz part anywhere on input or output, it's kind of irrelevant.

 

[AtomSoft]

Ah. Yes, "sort of" true. Actually the later models of PICs all have PLLs, so internal frequency is separate from the xtal freq. So the "mhz" part isn't even important. I could take a 1MHz xtal and use the PLL multiplier to get 40MHz internal freq and 10MIPs. Since you never actually see the 40MHz part anywhere on input or output, it's kind of irrelevant.

Is that true? I thought a PLL was something that multiplied the MHZ by 4 hence a 1MHZ would be 4MHZ? Am i wrong?

 

[DirtyLude]

A PLL does multiply the clock of the external crystal (not just by 4), but the idea that it means something is not correct. The core frequency is what is counted, not that of the external oscillator, which is irrelevant. All of these chips discussed here that work at higher frequency are rated at their internal frequency not that of the crystal. My 50Mhz Luminary chips are using 6Mhz crystals. So, if the chip is rated for 1/4 DMIP/Mhz, the Mhz it's referring to is the actual core clock speed.

I noticed the PIC32's are rated at 1.56 DMIPS/Mhz.

 

[AtomSoft]

oh ok cool... but i am sure that the PLL would be jumpy using a 1mhz to make a 40mhz correct?

 

[Pommie]

If you look at the 18F4550s oscillator section you will see that the input to the PLL is 4MHz and the output is 96MHz.

Mike.

 

[AtomSoft]

Thats cool! i guess i skipped a bunch of info seeing i barely use it heh...

 

[Oznog]

oh ok cool... but i am sure that the PLL would be jumpy using a 1mhz to make a 40mhz correct?

Not at all. The accuracy of the crystal and meeting the freq requirements on the input pin is all that matters. If it's 1% too fast, the end freq is 1% too fast after multiplication. There are no "jumps".

A lot of more advanced chips have flexible PLLs that don't just multiply by 4x. They can mult and divide by a wide variety of controllable ratios. They're widely used and work perfectly. This can get the full 10MIPs off the internal oscillator too (~7MHz usually, IIRC). The xtal can cost more than the PIC in small applications, so this is a dandy feature.

 

[spindrah]

its pretty hard to run out of speed with a DsPic33 running at 40MIPS

 

[AtomSoft]

heh i guess i need to relearn some things on that.

 

[gabeNC]

So what's your application Jason? Are you trying to 30fps on that LCD?

 

[AtomSoft]

heh na.. I plan on ordering a nice 3.5" TFT LCD (320X240) it has 60 pins but thats not the issue. Its 8 Bit *RGB Parallel meaning

8 pins for each R G B

So im sure i can switch that with a pic using Latched shift registers pretty fast heh but i want speed and the ability to do more than 1 thing at a time... which is what i assume threads are... I know that XMOS has enough power so ill be looking into it. The max i would want to do is about 15 frames a second.

 

[3v0]

Look at the UBW 32 from sparkfun $36. It is just a PIC32MX460F512L mounted on a small target board. You can get just the chip for about $8 if you can mount it on a breakout or make a PCB. It looks like it is a .5mm pitch part.

78 usable I/O pins

1.56 DMIPS/MHz (Dhrystone 2.1) Performance
at 0 Wait State Flash Access

So you are looking at 120 DMIPS !

But the XMOS is more sexy.

 

[AtomSoft]

400 mips xmos vErY SeCy

 

[be80be]

ATOM have a look at this Pilot’s Logbook

 

[AtomSoft]

OMG i just ordered that same RF module lol

 

[AtomSoft]

heh dont like Mikro really they overcharge but i do love there products heh...

Where can i get a joystick like that?

 

[be80be]

I've never bought a board from them but I like microC