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deign advice, soft mcu

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zuzu

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hello friends,

I just compute budget for a small project:

1. Cyclone III + power supply (quite the same price as fpga) + serial flash (replacement for very expensive altera serial flash by numonix) around 30$
I plan to use Nios/e (the free version)

2. MachXO (CPLD) or some 6K FPGA + power supply ~ 20...30$ (quite the same) but far less space to play (just 1200 LUTs). The good news is Lattice has a 8 bit MCU in 2...300 LUTs and seems to be nice.

3. Spartan 3 with PicoBlaze, quite in the same range.

4. Some CPLD only and external 8 bit MCU (Microchip, Atmel) with infinite much more support and experience at development tools (IDE, Compiler)


I'd appreciate few words about those software MCU's from practically experience. I need a small MCU (8 bit is enough) for 2 UART streams and one 4x20 char LCD, keys, etc, something that I normally fit in some PIC18, PIC24 or ATMega without any problems.

Thanks in advance,
 

alexan_e

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I don't understand, you say
I need a small MCU (8 bit is enough) for 2 UART streams and one 4x20 char LCD, keys, etc, something that I normally fit in some PIC18, PIC24 or ATMega without any problems.
If what you need is a microcontroller why would you consider to use FPGA just to implement an mcu core, it would only make your task more difficult.

Alex
 

zuzu

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Sorry, I didn't specified. I need a very high speed glue logic around. The mcu is only the accessory here :) Is supposed to initialize some other peripherals on board and provide a link for debug/logging purposes only. I can use any mcu with 2 uart and some I/O for driving a small lcd but I thought will be nice to implement inside if not so trouble and exorbitant IP costs.
 

alexan_e

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My personal option (as a hobbyist) would be to use number four, a CPLD to take care of the high speed logic and an mcu for the peripherals because it will give you more flexibility and would be much easier to use.
I have tried to use mcu cores in FPGA but i was barely able to execute a couple of simple examples, it seemed complicated so I have decided to use FPGA for things that an mcu couldn't do as fast as I wanted like interface with an ADC , ram interface etc and use an AVR for LCD , UART etc.
On the other hand if you want to have the experience and try with an mcu core or you think that you will need it in the future then you can try an fpga.

Alex
 

andre_teprom

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I´d used the PSoC fammily (CY8C43xxx) from Cypress.
That architecture implements an integrated mix of 51 core uC + FPGA at low scale.
It´s very intersting and easy to use.
Seems like matching the 4th option above.

+++
 

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