Hi fellows,
currently I've figured out a really, really strange behavior.
I designed a custom ArduinoMega board.
Then I flashed the bootloader by ISP and connected this board to my computer with an ArduinoUno board without AtMega238 (just removed the controller to use the serial converter only).
So far everything works fine.
Programming worked like a charm.
But now one of the users has a microcontroller that was flashed empty.
Bootloader still works and after dumping the memory I've seen this:
:1000000071C0000081C000007FC000007DC0000002
:100010007BC0000079C0000077C0000075C0000000
:1000200073C0000071C000006FC000006DC0000010
:100030006BC0000069C0000067C0000065C0000020
:1000400063C0000061C000005FC000FFFFFFFFFF52
:10005000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFB0
:10006000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFA0
:10007000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF90
:10008000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF80
:10009000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF70
:1000A000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF60
:1000B000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF50
:1000C000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF40
:1000D000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF30
:1000E000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF20
:1000F000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF10
:10010000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
:10011000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEF
:10012000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFDF
:10013000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFCF
:10014000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFBF
:10015000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFAF
:10016000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF9F
:10017000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF8F
:10018000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF7F
:10019000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF6F
:1001A000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5F
:1001B000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF4F
:1001C000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF3F
:1001D000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF2F
:1001E000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF1F
:1001F000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF0F
:10020000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFE
...and so on...
So I wonder how this could happen.
If this happened a single time, I wouldn't wonder - just an user mistake, flashing an empty sketch.
But it happened twice, with two of my circuits.
And one of them absolutely didn't get in contact with an computer after being installed.
So what could cause this behavior?
I just have seen the hex-dump of one of the machines yet. But the second one didn't get in contact with any computer since it has been set-up properly.
Is there anything that can clear my sketch by hardware?
Or any known strange behavior of the arduinobootloader to clear a sketch without using a computer?