# All AVR part can be programmed using ISP, you may find a small ISP
serial board at www.vmdesign.com. This is an important thing when doing
prototype, program and reprogram just by plugging a connector ...

# All AVR have integrated EEPROM that allow to save some parameters, depending
the application this can be or not an advantage, but save space and code when
needed an EEPROM.

# AVR have 16 register connected to the ALU, that allow really faster
processing than PIC, so they are TRUE RISC !. Doing just a register
manipulation will take exactly twice the code place with PIC than needed
in an AVR.

# AVR have a FLAT addressing scheme, allowing direct RAM manipulation
even on I/O and register that are only artificially separated. 3 direct
pointer allow indirect manipulation with auto-increement.
No bank switching is needed here. 40 Pin AVR can be extended with external
SRAM if necessary.

# Interrupt response time: Only one register need to be save, the other can
be just moved into low area. This allow really quick INT response.

# A Very important point is the STACK: most of PIC have a stack limited
to PC saving and 8 level, many user forget that !
AVR have a real stack, allowing pushing and poping parameters. This make it
high level language friendly, C, PASCAL ... and really simplify programmer
life.
In addition multi-tasking can be done here using the stack instead of
heavy PC register manipulation ...

# About wake up capability: This is true when using a crystal, the condition
need to be matched during the oscillator wake-up, that means at least
during 10 to 18 ms depending the crystal. But this can be dramatically
reduced to a few microsesond if using a ceramic resonator, when crystal
precision is not needed.
In addition this wake up condition is true for POWER-DOWN mode that is
different from SLEEP mode.
Nether forget wake-up will take at least the same time, whatever the micro-
controller used.

# AVR does not have brown-out circuitery, so you may need to use an external
RESET brown-out circuit: DS1811, MIC705, MAX...

# Price in small quantity (<500) are higher than PIC, this is also a
problem with AVR, I believe this is due to FLASH and EEPROM presence that
make the price difference.

# Some good compiler and tools are available: C ImageCraft, Embbeded PASCAL,
AVR Basic, AVR-RTOS, UMPS ...

Regards,
        Philippe.

  +--------------------------------------------------------+
  | Virtual Micro Design                                   |
  | UMPS: Universal assembler/disassembler/simulator       |
  |        for AVR, PIC, HC05, HC11, 8051, ST6, HOLTEK ... |
  |                                                        |
  | E-Mail: info@vmdesign.com                              |
  | URL:    http://www.vmdesign.com                        |
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