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Author Topic: Uploading sketch to homemade arduino  (Read 581 times)
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Hi,
I am trying to build my own Arduino.
I am following this tutorial:
http://tronixstuff.wordpress.com/2010/06/14/getting-started-with-arduino-chapter-ten/
http://tronixstuff.files.wordpress.com/2010/06/example10p1schematicsmall.jpg
http://tronixstuff.files.wordpress.com/2010/06/worksftdismall.jpg
There are only 2 notable differences:
1) I use 12 MHz resonator.
2)Instead of FTDI cable I use Sparkfun FTDI Basic Breakout - 5V.
http://pvelectronic.inshop.cz/inshop/scripts/shop.aspx?action=DoChangeLanguage&LangID=4

I am able to run my homemade Arduino if sketch is uploaded on my UNO,hovewer I am not able to upload any sketch to this chip using FTDI Breakout.
Is there any difference if I use FTDI Breakout  instead to FTDI cable?
Is there any tutorial available?
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Have you installed a bootloader on your homemade version?
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The cable and breakout are exactly the same, just look at their schematics.
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Have you installed a bootloader on your homemade version?


I tried to use:
1) Chip from my UNO board.
2) Chip supplied by vendor http://pvelectronic.inshop.cz/inshop/scripts/shop.aspx?action=DoChangeLanguage&LangID=4

Both of them worked,if sketch was uploaded in my UNO board and subsequently used in homemade version,but neither of them uploaded sketch thru FTDI
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The odds are stacked against you trying to use a 12 Mhz resonator. The serial communication driven by the bootloader is dependant on the clock frequency of the 328. To get it to work at 12 Mhz, you'd need to reprogram the bootloader.  The chip will happily run at 12 Mhz, but you can't expect timing critical operations like serial to work without recoding the bootloader. 
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In theory there is no difference between theory and practice, however in practice there are many...
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Thinking out loud,
you might do some serial communication if you configure different port speeds (PC/arduino) that have the ratio 12: 16 = 3:4
See the table below, two of them could be working as the ratio 3:4 give stanbdard speeds.
(however uploading sketches is done at 57600 so therefor it might not work ...)


3/4       baud    4/3
----------------------------------
225      300      400
900      1200     1600
1800     2400     3200
3600     4800     6400
7200     9600     12800
10800    14400    19200   -- these could be working!!
14400    19200    25600
21600    28800    38400 -- this could be working too
28800    38400    51200
43200    57600    76800
86400    115200   153600
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Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
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The odds are stacked against you trying to use a 12 Mhz resonator. The serial communication driven by the bootloader is dependant on the clock frequency of the 328. To get it to work at 12 Mhz, you'd need to reprogram the bootloader.  The chip will happily run at 12 Mhz, but you can't expect timing critical operations like serial to work without recoding the bootloader. 

Thanks for this idea-I replaced resonator with 16MHz and it works fine.:-)
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