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Need help choosing microcontroller
- 10-12-2003
- William Wuister
October 12, 2003, 3:29 pm

I need to find a microprocessor with the following requirements. I
currently use a PIC 16F876. I need to add a lot of software to the
product and don't have enough room in the pic.
- at least 3 10-bit (or greater) a/d converters
- 16 programmable digital i/o pins
- 32-bit
- execute from RAM
- free C cross compiler
- address 1 meg of memory (ROM and RAM)
- pulse width output
- programmable interrupt pins
- timer interrupts
- serial port registers and interrupts
- fast: need to compute realtime physics using floating point math.
thanks,
William

Re: Need help choosing microcontroller

Except for the A/D converters, the thing could be an Atmel AT91, e.g.
AT91R40008. It's based on the ARM7TDMI 32-bit core and contains plenty for
your other requirements.
IMHO, external A/D's are much easier to handle because of less digital
noise. I'd use any of the SPI converters with the AT91. It's not difficult
to bit-bang them on the AT91 I/O ports.
The GNU toolchain (gcc, as, ld, objcopy, gdb ...) supports the chip.
HTH
Tauno Voipio
tauno voipio @ iki fi

Re: Need help choosing microcontroller

The philips LPC2106 has 64kB RAM and 128kB FLASH onchip, but no ADC, has
I2C and SPI though so you could use an external ADC. ARM core, so gnu
compiler available.
The AT91M55800 has internal ADC but needs external memory (128MB max),
also ARM core. I think atmel may have closer matching parts, have a look.
--
Stef
Blessed are they who Go Around in Circles, for they Shall be Known as Wheels.
Stef
Blessed are they who Go Around in Circles, for they Shall be Known as Wheels.

Re: Need help choosing microcontroller

Small comparision
AT91M55800: Internal ADC, 8 kB SRAM, 33 MHz
AT91M40008: External ADC, 256kB of SRAM, 66 MHz. (60 MIPS when internal
operation)
AT9RM9200: External ADC, 16 kB SRAM, 16k+16k cache, Burst Flash, SDRAM,
180 MHz is even better.
--
Best Regards
Ulf at atmel dot com
Best Regards
Ulf at atmel dot com
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Re: Need help choosing microcontroller
questions about this.
Does it have a hardware floating point coprocessor? I didn't see that
it did, but I haven't yet found full documentation on the processor.
Where can I find a full instruction set description?

Re: Need help choosing microcontroller

No. It's a pretty pure RISC without even a divide instruction.

There are documents on the ARM site.
Also, the ARM7TDMI manual is on the Atmel site documentation part.
For complete information, get also the AT91R40008 and AT91X40X data sheets
from the same Atmel location.
HTH
Tauno Voipio
tauno voipio @ iki fi
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