Microcontroller with excellent EMI/EMS and external RAM ?

[MicroCoder9]

how shielding to reduce noise for microcontroller

Hi all,

I need a microcontroller with following features for an industrial control project:

- Flash memory > 32 K bytes
- 2 UARTs
- 1 synchronous serial port such as SPI
- support for external RAM interface
- 5V supply voltage
- excellent EMI/EMS noise immunity

Please can anyone suggest a robust microcontroller with above features ?

Thanks,

MicroCoder9

 

[IanP]

avr external ram

Quite good option is the DS89C440 (450).
It has 8052 core and supports external RAM ..
Link with info:
**broken link removed**

 

[gorkin]

noise immunity for microcontroller

Why the necessity for external RAM? Atmel company have excelent microcontrollers (see more AVR series in atmel.com) with considerable RAM space for many applications.

Gorkin.

 

[MicroCoder9]

microcontroller ic for noisy and emi environment

Thanks IanP for providing link to Maxim's microcontroller info. It seems to be a good microcontroller.

I understand that it has an option of switching off ALE, when not needed, to reduce noise emissions.

However, I want to know, how good is it as far as noise immunity is concerned. Has anyone used it successfully in designs for highly noisy industrial environments?

Thanks gorkin for your suggestion about Atmel's AVR series. Some of my friends have used AT90S2313 and AT90S8515 from AVR series and found them to be inadequate (only marginally better than Atmel's 8051 based micros) for noisy industrial environments. Is the ATmega series any better in this regard?

I need to use 32K bytes (128K bytes with full options) RAM for my control application. I believe it will be cost effective to use a good micro + external RAM combination than a micro with very large in-built RAM.

 

[glenjoy]

microcontroller that can address external ram

Thanks IanP for providing link to Maxim's microcontroller info. It seems to be a good microcontroller.

I understand that it has an option of switching off ALE, when not needed, to reduce noise emissions.

However, I want to know, how good is it as far as noise immunity is concerned. Has anyone used it successfully in designs for highly noisy industrial environments?

Thanks gorkin for your suggestion about Atmel's AVR series. Some of my friends have used AT90S2313 and AT90S8515 from AVR series and found them to be inadequate (only marginally better than Atmel's 8051 based micros) for noisy industrial environments. Is the ATmega series any better in this regard?

I need to use 32K bytes (128K bytes with full options) RAM for my control application. I believe it will be cost effective to use a good micro + external RAM combination than a micro with very large in-built RAM.

I think the Ds89C450 is good for noisy environment, you can select a lower crystal frequency and a stable one then just use the internal frequency multiplier of the micro. Sometimes mostly electronics design involving noisy environments requires a good shielding.

 

[IanP]

atmega88 emi

In niosy environments one have to use special precautions to isolate a microcontroller from external noise. It is not the case of selecting a microcontroller to be noise immune; this is up to designer to ensure that a microcontroller has proper environment.

Some of these precautions will include dc-dc conversion on supply of the microcontroller, implementing optical isolation on digital inputs/outputs, using isolated opamps on A/D and D/A lines et cetera..

I suggested the DS89C... microcontroller not because it is totally noise immune, but because it fulfills your other hardware requirements.

The EMI/EMS issue is your responsibility .. : isolation, shielding, de-coupling etc..

 

[agha]

maxim microcontroller

Hi
I think motorola microcontroller such as HCS12 series can help you about it.

 

[Hero]

Re: Microcontroller with excellent EMI/EMS and external RAM

Hi,

I think that Atmel ATmega128 is excellent choice.

You can use 4K on-chip SRAM for STACK and fast communication buffers.

You can use different wait-states for different blocks in external RAM space. So you can trade-off between EMC requirments and system performances.

External SRAM bus interface is very simple without glue logic.

Also you can reduce power consuption and EM radiation using 3.3V instead 5.V. You can extend external SRAM 64K linit using PORTG pins for address decoding without glue logic.

Process power is up to 16MIPS at only 16MHz with power consuption less than 0.12W at 3.3V.

 

[artem]

It seems better to use inbuilt ram devices such as newer ARM based chips (ram upto 64 and more) which are as chip as their 8 bit counterparts .

I did not find significant difference between ATMEGA 128 and ARM with 32 kbit ram in price terms , but for the first one you have to pay for additiona ram chip , and of course this puts ARM in better position, even if we do not talk about other ARM over AVR advantages .