DIY Mega Board Issue - uploade hex file

Projects General Guidance
1

hello, Arduino

i need your help, i have 2 question to solve,

one question is, when we check Mega's schematic,
we can check Atmega8U2 chip that for support usb uploading.
so then if i make my diy board and using "SPI" port to write down do i need this chip?
-> i have dc-dc converter to supply ext 5V for atmega 2560

and the other question is
my DIY board need bootloader to operating "ino" file
so, it can be possible to upload both files at once to empty chip?
both files means -> one is mega's bootloader.hex and the other file is fw.hex that come form export by arduino IDE

becaous of this two question, i can not finish my schematic job
please help,

thatnks for looking,
best regards

2

No, you don't need the TTL-to-USB converter if you only want to upload via ICSP (SPI port). You however need it if you want to communicate with a PC over USB (upload over USB or serial prints in your code), but that does not necessarily have to be on the board (there are external adapters that you can use).

When you use 'export binary', it will generate two hex files, one with and one without bootloader; there seems to be a little disclaimer here that it might not always generate a correct one with the bootloader; see "Export compiled Binary" do not compile a long code's the with_bootloader hex file. Why?.

That needs an explanation; you only need a bootloader if you want to upload via the USB (serial port).

I've moved your topic to a more suitable location on the forum as I did not see you make a suggestion for the Arduino project :wink:

3

Thanks for help, sterretje
it's really big help, now i understand

when i made prototype model i tried export binary and upload to the other board and checked it's worked
Result is good : )

but at that time, the other board also arduino MEGA board means bot DIY board, its own MEGA board

that's why i had some unsolved question
"try to make it small DIY version, but how can possible to upload"
but it's almost solved

I dot' have any plan to communicate with pc via usb
so, i don't need ttl chip

and

then i don't need to upload bootloader also i just need exported hex file from IDE

could check it for me,
am i understand your help clearly and my decision is good?

thatnks for looking,
best regards

4

Correct

Correct

Correct

5

I do what you’re doing every day with a MEGA-1284 board.
I compile normally, save the hex.

I do support the boot loader and serial I/o but it’s off board.

Later, I use avrdude to flash new, empty boards, and away they go.
If I do need the serial upload, I add optiboot to the image and that gets flashed along with the hex when needed.

One pass / easy every time.
If I’m pushing out a few boards, use a JTAG ICE (ISP programmer) faster, and boot loader not necessary.

6

Nice and clear
Thanks sterretje

7

also can possible download hex file use another tools,
thanks for help lastchancename : )

8

If you’re using an ISP programmer like ICE, and fuses aren’t locked, yes you can read the memories - as well as writing them.

9

@sterretje and @lastchancename

here's my new update now i'm finish to make my own pcb board and waiting "USB ASP"
to try upload hex file to my board

i will update after check working
Thanks for help

best regards

10

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