50+ MIPS flash MCU needed

LPC2101 ARM satisfies 50 MIPs and fast/cheap, but no internal osc.

Hi Antti,

Pin count ? Other resourced needed ? Level of maths required ? Any op-code speed mins ?

-jg

Assuming 'not much flash' also means 'not many pins' : The cheapest device, on cents/MIPS, by far, is the new SiLabs C8051FT6xx

- all variants have the CalOsc, and Silabs claim "pricing beginning at $0.45 in quantities of 10K", so that's under

2cents/MIP - this also runs at full speed, down to 1.8V, as I'm guessing Lower voltage matters more to you than 5V.

-jg

Freescale 56F8xxx "hybrid" DSP's might fit the bill. Some of them are pretty small and cheap, and they have good and fast internal oscillators.

Small ColdFire devices might be another choice, depending on what you mean by "cheap".

Not sure if by "internal oscillator" you mean a free running clock or a crystal oscillator on chip with external crystal. The Luminary Micro Stellaris parts contain an internal free running clock. This runs at 15 MHz, but you may be able to run this through the PLL to get the 50 MHz you need. Typically the internal clocks are not very accurate or temperature stable. So you may have to set it to something well below 50 MHz to make sure it is within the correct tolerance. I expect this is going to be an issue with nearly any 50+ MHz processor, but not so much with the slower, low end parts around

4-20 MHz.

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Take an ARM and execute out of SRAM.

Most ARMs have an oscillator on chip (but you maybe wanted an onchip R/C oscillator :-) If so, what is the problem in having an external resonator? You did not mention package size?

What is "not much flash"?

Internal studies shows that SAM7 has faster access to SRAM than LPC. Asked a question here if anyone else seen the same thing, but saw no reply.

--
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

You may want to take a look at TMS 28xx series, although it is 32 bit.

VLV

Hi,

first I would not know about a PIC approaching 50 MIPS.

What about the LPC2364, not really small but really good price and has internal oscillator. Gives you >60 MIPS internal Flash, 4 MHz oscillator + PLL.

Robert

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Most high speed micros are 32 bit, but they are dropping in price.

If by internal oscillator, you do not mean internal R/C oscillator, you can always run an ARM from internal SRAM to get max speed.

Internal tests shows that an SAM7 is superior to LPC parts when both are executing from SRAM at the same clock frequency. I asked a question some time ago, if anyone seen similar results but got no replies.

How much flash is needed?

--
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

I am not sure you can do that. Part of the PLL configuration is to switch to internal clock temporary. The internal clock is likely to be completely independent from the PLL (at 200 MHz). If he wants

50MHz, external crystal is unavoidable.

Typically the internal clocks are not very

I am pretty sure you can use the internal clock in conjunction with the PLL. The block diagram shows that pretty clearly. I have not tried this, but I don't see any caution against this in the manual and I don't see a spec limitation that would prevent it.

Ahhh, here it is from the LM3S601 manual, page 83.

Oscillator-Related Bits

5:4 OSCSRC R/W 0x0 Picks among the four input sources for the OSC. The values are: Value Input Source 00 Main oscillator (default) 01 Internal oscillator 10 Internal oscillator / 4 (this is necessary if used as input to PLL) 11 reserved

Notice the /4 setting on the internal osc is used when sourcing the PLL with this clock.

It is important to consider that the internal clock has a WIDE variation over temp, voltage and process... 7 to 22 MHz with 15 typical. Perhaps one of the LPC or SAM7 parts would have a tighter internal clock rate? Or you can adjust the PLL to optimize the running rate if you have an external reference of any kind, such as a baud rate input on a UART?

The limitation is that it is difficult to do so.

As you said, the internal clock could be 7 to 22 MHz. 1/4 freq. would be 2 to 5 MHz. You would have to constantly adjust the RCC for source freq. Otherwise, the PLL can get out of lock and your timings are screwed. Or worst, the micro can lock up with out of range clock source.

Yes, you would need to adjust the PLL settings to keep a constant frequency. But a drift in the internal oscillator would not cause a "lock up" or other failure in the PLL. At least there is nothing in the documentation that indicates this.

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Thanks Ulf, and all other who responded. gather some interesting but did not find the chip i was looking for :( it does exist - TQFP64 package. But doesnt seem to be any known candicate (checked almost all mcu's i can think of).

the task is "low cost CPLD emulation" - so needed is only one feature FAST bit bang I/O

Antti

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Hi Antti,

The fastest at handling boolean expressions has to be the 80C51, as it has native boolean opcodes - but it's a strange task ?

Why try and do low cost uC-CPLD emulation, when you can already buy low cost CPLDs, in ISP Flash ?

I'm trying to think what a uC could offer, that a genuine CPLD would lack ? Do you perhaps mean vector testing of CPLD ?

-jg

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Jim

TOTAL BOM cost has to be below 2.5 USD in qty 10K XC9536 is too small :( with some bigger CPLD+MCU the BOM cost raise too quickly :(

would need downgraded MAX2 smallest device under 3USD that could do the task

XC9572 alone too small when add MCU already sums up in cost

Antti

How much CPU resource do you need, and what does the CPLD need to do ?

We use CPLD+uC a lot, and there are often a number of ways to split the tasks, to keep the BOM down. (but I'm sure you'll know that aready..)

The Atmel CPLDs are good at packing logic, with care, you can get up to 3 node names per macrocell, and their new ATF150xBE series measure up well.

-jg