Objective Development Forums

Hi,

I have a strange problem with my test assembly (on stripboard).

Parts I have used:
1x ATTiny 24A
1x 16 MHz crystal
2x 22pF caps (already tried with 33pF)
3x 100nF
2x zener diode BZX 55B 3V6
1x 1,5K resistor
2x 68R resistor
1x 10K resistor
USB connector and some LED's

When I plug in the device, I will hear the "connect" sound from Windows7 ... after one or two seconds again and again and again...
(The device-manager refreshes every time (cause connect loop), so I can't see if the device was recognized)

My fuses seems to be ok: only SPIEN and EESAVE are unset. (high crystal, slow startup, no clkdiv...)

As code I have used the hid-mouse example project (Jup, I did the modifications on usbconfig.h / F_CPU)
and compiled it with Atmel Studio 6.

I have soldered D+ to PA2 and PB2(INT0)
and D- to PA1.

The usbasp schematic was my template for this ciriut: http://www.fischl.de/usbasp/

Has anybody an idea what is going wrong here?

Well I dont have exp. with the ATTiny 24A but your part list looks good. Are you using a descriptor you know works.

ulao wrote:Well I dont have exp. with the ATTiny 24A but your part list looks good. Are you using a descriptor you know works.

Yes. I have two usbasp's and tested the firmware with one of them -> works great.

Now I have found out that this only happens, when I use a hub. (scared of a damaged notebook usb port^^)
If I plug it in directly then nothing happens. -really nothing....
If I unplug the µC then Win7 announce an unrecognized device.

I had a very similar issue. In my case though the ZDiodes where just normal diodes ( mistake from my board maker ). The other thought that comes to mind is some chips will not work on 1 watt diodes and need to be 1/2 watt. Though it looks like the BZX55B3V6 is ok.