There is no pre-existing definition in the Arduino IDE for a board with Optiboot at 8MHz, but it's easy to add one: Find the boards.txt file and duplicate the uno definition (the first block of text). Change the uno prefix in the duplicated text to something else, change upload.speed to 57600, change f_cpu to 8000000L, and change name to something else.
Likewise you can burn a bootloader binary made for an 8MHz board onto a chip running at 16MHz. To test it with the 16MHz crystal you just need to upload at twice the normal baud, and to do that you make a new entry in boards.txt as described above.
optiboot_8MHz.name=Optiboot @ 8MHzoptiboot_8MHz.upload.protocol=arduinooptiboot_8MHz.upload.maximum_size=32256optiboot_8MHz.upload.speed=57600optiboot_8MHz.bootloader.low_fuses=0xffoptiboot_8MHz.bootloader.high_fuses=0xdeoptiboot_8MHz.bootloader.extended_fuses=0x05optiboot_8MHz.bootloader.path=optibootoptiboot_8MHz.bootloader.file=optiboot_atmega328.hexoptiboot_8MHz.bootloader.unlock_bits=0x3Foptiboot_8MHz.bootloader.lock_bits=0x0Foptiboot_8MHz.build.mcu=atmega328poptiboot_8MHz.build.f_cpu=8000000Loptiboot_8MHz.build.core=arduinooptiboot_8MHz.build.variant=standardoptiboot_16-8MHz.name=Optiboot 16MHz >> 8MHzoptiboot_16-8MHz.upload.protocol=arduinooptiboot_16-8MHz.upload.maximum_size=32256optiboot_16-8MHz.upload.speed=115200optiboot_16-8MHz.bootloader.low_fuses=0xffoptiboot_16-8MHz.bootloader.high_fuses=0xdeoptiboot_16-8MHz.bootloader.extended_fuses=0x05optiboot_16-8MHz.bootloader.path=optibootoptiboot_16-8MHz.bootloader.file=optiboot_atmega328.hexoptiboot_16-8MHz.bootloader.unlock_bits=0x3Foptiboot_16-8MHz.bootloader.lock_bits=0x0Foptiboot_16-8MHz.build.mcu=atmega328poptiboot_16-8MHz.build.f_cpu=8000000Loptiboot_16-8MHz.build.core=arduinooptiboot_16-8MHz.build.variant=standard
1.) because I successfully flashed Optiboot (using the Otiloader sketch.. that auto detects chip signature) in a jig/circuit that was set-up with 16MHz external crystal,..... I can just take that chip out.. and pop it into the 'final' circuit that is set-up to use an 8MHz external resonator.. and have ZERO problems? side effects?......nothing??
2.) There is no 'pre-existing' entry in the boards menu in the Arduino IDE for ANYTHING Optiboot related? 16Mhz or 8Mhz??
now this seems like an answer to addresses my current situation/problem...(correct?)
Quoteoptiboot_16-8MHz.upload.speed=115200You cannot run 115k2 upload with 8MHz clock reliably. The max recommended is 57k6..
Quote from: xl97 on Apr 09, 2013, 08:08 pm1.) because I successfully flashed Optiboot (using the Otiloader sketch.. that auto detects chip signature) in a jig/circuit that was set-up with 16MHz external crystal,..... I can just take that chip out.. and pop it into the 'final' circuit that is set-up to use an 8MHz external resonator.. and have ZERO problems? side effects?......nothing??That's right. The only extra thing you'll have to do is add an extra entry in boards.txt. You have installed an Optiboot binary which is made for running at 16MHz. It will still run at 8MHz, but at half the speed. The only change you have to make is ensure that the communications coming from your PC are also running at half the normal speed.Quote2.) There is no 'pre-existing' entry in the boards menu in the Arduino IDE for ANYTHING Optiboot related? 16Mhz or 8Mhz??No, that's not right. The Uno, the Arduino Mini, and the Arduino Ethernet all use Optiboot at 16MHz.Quotenow this seems like an answer to addresses my current situation/problem...(correct?)I'm not quite sure that your current problem is. If you've got Optiboot running, isn't that enough?
Found the summary I was doing.You can see I was toying with a new board type:the existing 328 types with 20 IOthe existing 1284 types with 32 IOa new 1281 type with 54 IO, "milliduino"the existing 250 types with 86 IOI should make one up & try it ...
I have what I believe to be a FLASHED chip with Optiboot on it. Since it 'auto detects' the chip signature.. and there is no 8Mhz version.. (and you cant choose anyways.. Optiloader just 'goes'..and runs when a chip is detected)... this chip is set-up to use 16Mhz.which Im assuming will NOT work in the final/target board that is set up with an 8MHz external resonator..
1. if you flash an "optiboot for 8MHz and 57k6" and run the chip @16MHz the upload baudrate will be 115k2 - ok2. if you flash an "optiboot for 16MHz and 115k2" and run the chip @8MHz the upload baudrate will be 57k6 - ok
Quotethat being said.. 'is' moving toward +3.3v based boards the trend? (future?)..Yes.
that being said.. 'is' moving toward +3.3v based boards the trend? (future?)..
I flash Duemilanove with the Arduino as ISP sketch.. ...wire up board..make sure com port is right... choose - Arduino Pro/Pro-Mini @+3.3v & 8MHz entry from BOARDS menu..and then choose BURN BOOTLOADER..
"Flashing a chip" and "running a bootloader" are two different instances. You may flash a chip with "any recommended crystal value" connected to it, afaik (provided you are using a standard programming method).