When I connect it to the pc he doesn't recognise him.
Now could it be that I need to regulate the supply voltage to 3.6 and not the data lines? Or could there be something else wrong ?
I wish to know some opinions before I start changing things on my test-board.
Greetz...awen - Apr 21, 2008 - 01:46 PM Post subject: RE: BootloadHID with ATmega8 schematic
Hi. I'm using the same bootloader for a long time, and there is no problem on the schematic.. Check twice you connection (pullup on D- dataline, polarity of zener diodes, and correct connection of D+ and D-).. then check fuse bits.. program the fuse bits as they are exampled in source code -- don't forget to program BootReset Vector fuse bit (as I forget some time ago, and had a lot of headache ) and of course Bootloader size and oscilator bits
good luck, it must be all right DenDraad - Apr 21, 2008 - 03:12 PM Post subject:
Thanks for your reply awen.
I will try it and post when I've tried it.
GreetzDenDraad - Apr 23, 2008 - 11:26 AM Post subject:
Hello,
I feel very stupid, I turned the polarities of the zener diodes.
Now there is connection between the pc and the device.
But it says that the device is not recognised.
And when I try to flash it with FW uploader, it says "The specified device was not found".
Could it be that I need to change my zeners because when I check the voltage it reads 4.00V maybe its just the meter thats a little of (I did use zeners from 3,6V).
Any ideas what could be wrong ?
Greetzawen - Apr 24, 2008 - 01:09 AM Post subject:
I'm not sure if you understand that firstly you must use "normal" programmer to program bootloader code, and after that you can simply upload flash with attached command line tool.
If you have your uP flashed and programmed fuses correctly, there can be another problem with zener diodes -- don't use power zener diodes because of parasitic capacitance and some similar things (I don't know exaclty). I'm using small 0.25 Watts 3.6V zener diodes with no problem.
I have no idea what else can be wrong. I hope it helps you. Drop a line if you figured it out ka7ehk - Apr 24, 2008 - 01:40 AM Post subject:
Have you loaded the loader into the AVR? You have to do that with some other programming method (ISP, jtag, etc).
Zeners are correct as drawn. Their only purpose is to protect the AVR against transients on the USB data lines. It will work without them.
JimDenDraad - Apr 28, 2008 - 11:45 AM Post subject:
thanks for the response
and yes,
I programmed the bootloader in the ATmega8 with
STK500. Set the fuses and so.
but still nothing... the zeners are correct and everything now. Could there be any other cause?
Really getting frustrated
Greetzawen - Apr 28, 2008 - 07:57 PM Post subject:
So, I look at default source code, and I found something
Bootloader condition (jumper) is set in code to PORTD bit 3, not PORTC.2 as in schematic. So try connect PORTD.3 to ground DenDraad - Apr 28, 2008 - 09:54 PM Post subject:
Hey awen (and all the rest),
Thanks, I did found the fault already by myself today.
And the bootloader now works perfect !
For what purposes do you use this ?
What do you do with your chip ?
(If you want to, post some pictures ?)
I'm just curious..
Greetzawen - Apr 29, 2008 - 01:04 AM Post subject:
Please write what fault was there, I'm curious too
I haven't any special purpose for bootloader. It's simply "handy" to have this in uP while the design is not 120% tested and developed (but design is already 'outside' the bread board), and if you know that new version of software will be made and your product is already sold to customers..DenDraad - Apr 29, 2008 - 01:52 PM Post subject:
Like you said, the jumper was wrong connected.
But I did found It before I did read your post .
But many thanks !!
I'm glad It works now because It's for school, for my end exam..
) and of course Bootloader size and oscilator bits 
