V-USB and ATtiny861

[JulsPower]

Hi
I wish to try V-USB for the first time
is it possible to run on the internal ATtiny861 if its supplied at 3.0V?
the documentation isn't very clear on this, I know I can run a lower voltage
and I know it is possible to run it with the internal RC, but both together?

Thanks for the info
if not an external crystal is required right?

[andi]

Hi
I wish to try V-USB for the first time
is it possible to run on the internal ATtiny861 if its supplied at 3.0V?

Read the datasheet again, it is pretty clear about this.

You can run the 861A from the "High-Frequency PLL Clock", just like the 85.

However: vUSB needs at least 12MHz, but the datasheet for the 861A says maximum save operating frequency @3V is 11.66MHz, just a bit outside of the save operating area. Furthermore, only the 12.5 and 16.5MHz modes of vUSB allow the use of the RC oscilator, which then would require at least 3.333V.

Finaly, if by 3.0V you meant two batteries - you get 1.5V only with brand new ones. When fully discharged, they have 0.8-1V each, and the maximum save operating frequency for the 861A @1.8V is only 4MHz.

[WitchDoc]

I'm a little confused by this answer?

Read the datasheet again, it is pretty clear about this.

You can run the 861A from the "High-Frequency PLL Clock", just like the 85.

Ok, clear. So it probably is possible, the internal clock runs at 8Mhz, the PLL is used to generate 16.5 Mhz from that.

However: vUSB needs at least 12MHz, but the datasheet for the 861A says maximum save operating frequency @3V is 11.66MHz, just a bit outside of the save operating area. Furthermore, only the 12.5 and 16.5MHz modes of vUSB allow the use of the RC oscilator, which then would require at least 3.333V.

First; vUSB can run from the internal 8Mhz clock by using the PLL, just like the tiny85, you just wrote that! Where does this 12Mhz suddenly come from? Second; Where does the 3.333V requirement come from? Where does the datasheet say that you need 3.333V for the RC oscilator?

[quite="andi"]
Finaly, if by 3.0V you meant two batteries - you get 1.5V only with brand new ones. When fully discharged, they have 0.8-1V each, and the maximum save operating frequency for the 861A @1.8V is only 4MHz.[/quote]

Where does the TS mention batteries? If the thing is connected to the USB port what use are the batteries?

[WitchDoc]

I'm a little confused by this answer?

Read the datasheet again, it is pretty clear about this.

You can run the 861A from the "High-Frequency PLL Clock", just like the 85.

Ok, clear. So it probably is possible, the internal clock runs at 8Mhz, the PLL is used to generate 16.5 Mhz from that.

However: vUSB needs at least 12MHz, but the datasheet for the 861A says maximum save operating frequency @3V is 11.66MHz, just a bit outside of the save operating area. Furthermore, only the 12.5 and 16.5MHz modes of vUSB allow the use of the RC oscilator, which then would require at least 3.333V.

First; vUSB can run from the internal 8Mhz clock by using the PLL, just like the tiny85, you just wrote that! Where does this 12Mhz suddenly come from? Second; Where does the 3.333V requirement come from? Where does the datasheet say that you need 3.333V for the RC oscilator?

Finaly, if by 3.0V you meant two batteries - you get 1.5V only with brand new ones. When fully discharged, they have 0.8-1V each, and the maximum save operating frequency for the 861A @1.8V is only 4MHz.

Where does the TS mention batteries? If the thing is connected to the USB port what use are the batteries?