Some of the difference are very well known like smaller bootloader size, faster flash programming by UNO, replacement of FT232RL with Atmega8u2, however I would like to explore more on the technical and implication part.
1) EEPROM write- This will be missed as I would in many cases write configuration data in eeprom like calibration file etc. Though eeprom can always be updated through user code.
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2) Adaboot no wait mode: This might have been added later in duemilanove, but it needs special mention.This is a check in bootloader to know the source of reset and react accordingly.Hence if uC enters bootloader due to watchdog reset or brown out reset it immediately leaves bootloader and jumps to main program.Hence other than hardware reset your uC will never enter bootloader.
3) Watchdog handling: The UNO bootloader has code to handle the watchdog timer if it is activated by setting WDTON in Fuse High Byte in your project. In older version the Arduino will stay in bootloader forever if WDT was enabled.
In addition to above some unnecessary zero initialisation commands are removed to save code space.
Hardware differences
1)On older boards, the FT232RL was also providing a free 3.3V output. In the UNO, a separate LP2985 LDO regulator produces 3.3V at 150mA DC from internal 5Volts.
2)The 16Mhz Crystal oscillator for Atmega328 is replaced with 16Mhz resonator (UNO Rev 3).
Board Reliability improvement upgrades
1)The UNO rev3 finally has diode to clamp reset pin voltage to 5Volts.
2)All UNO have varistor protection for USB D+ / D- signal lines. To prevent voltage spike destroying the Atmega16U2.
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Hi - your posted ends with ......cont which suggests that there is more content, but it is not a link. I'm not sure if there is more or not.
ReplyDeleteInteresting subjects, though! Thanks