ICSP with ATTINY45 and V-USB

[tkerby]

Hi
I've tried a few of the standard circuits for v-usb and attiny45 and am having difficulty using avrdude and a usbtinyisp programmer while the chip is in circuit. If I remove the chip and use the pogo pin harness I made direct to the pins then it works perfectly.

I've tried 5v power and no zeners on the data lines (e.g. capslocker project) and also using the two diodes or an led dropper on the usb power. Both options the device was not powered from usb and the programming lines connected directly to chip pins

Any ideas

[mschoeldgen]

As the ATTiny 25/45/85 have so few I/O lines it is unavoidable that the USB port sits on at least one of the programming lines ( you probably noticed that V-USB doesn't work if you use PB1 instead of PB0 and that you HAVE to use PB2 for D+). My project uses the tiny85 and i have to unplug USB for programming. The chip is powered by the 2 series diodes through 5 volts, but for programming i provided another 2 pin - header for an external supply - there's probably no way to power the chip by USB and program it simultaneously.
Also note that the 16.5 Mhz internal clock is on the edge for programming - you should supply 3.6 to 5 Volt to the chip while programming.


'Ow, btw is there a dedicated bug report form / forum ? Its no biggie but the Tiny's 25/45/85 really do not work with V-USB if using other ports than PB0 and PB2 , must be some minor thing.

[christian]

'Ow, btw is there a dedicated bug report form / forum ? Its no biggie but the Tiny's 25/45/85 really do not work with V-USB if using other ports than PB0 and PB2 , must be some minor thing.

There is NO such known bug. However, if you use an interrupt different from INT0, you need some extra config.