Overclcok AtmegaL

Hi,

I am going to overclock Atmega16L to 12MHz. I can do that when the JTAG
header is attached. However, when it is detached, the program seems to
be not working. I have tried to shut down the power of the emulator and
it still works when the JTAG header is attached. I do not understand
why this strange case happens. Could anyone talk to me why this
happens? As I need to use 3.3V, I need to use Atemga16L.

eeh wrote:

> I am going to overclock Atmega16L to 12MHz. I can do that when the JTAG

You are so 3L33T. RaDiCaL To THe MaX, DuDe.

> it still works when the JTAG header is attached. I do not understand

The JTAG might be holding down reset a bit longer than normal.

Remove JTAG, power up, use wire to reset device. Does it work?

larwe wrote:
> eeh wrote:
>
> > I am going to overclock Atmega16L to 12MHz. I can do that when the JTAG
>
> You are so 3L33T. RaDiCaL To THe MaX, DuDe.

Yeap, considering that they are plenty of Atmega16* at 16MHz,
and cheaper than 8MHz as well.

If you overclock a 16MHz part to 32MHz, that might be intereresting.

> The JTAG might be holding down reset a bit longer than normal.
>
> Remove JTAG, power up, use wire to reset device. Does it work?

I add RC at the reset pin which are 1M Ohm and 0.1uF respectively. But
it has no improvement and is stll not working.

And I hot plug the USB cable after reset.

Don't do it. Use a faster processor instead


"eeh" <eehobbyist@yahoo.com.hk> wrote in message 
news:1138558119.023935.294880@o13g2000cwo.googlegroups.com...
> Hi,
>
> I am going to overclock Atmega16L to 12MHz. I can do that when the JTAG
> header is attached. However, when it is detached, the program seems to
> be not working. I have tried to shut down the power of the emulator and
> it still works when the JTAG header is attached. I do not understand
> why this strange case happens. Could anyone talk to me why this
> happens? As I need to use 3.3V, I need to use Atemga16L.
> 

OK after adding 10uF decoupling cap at 3.3.V supply

i suggest you run a test over the complete temperature range.

It might run overclocked at 25 degrees ,but may fail in a hot summer.
Bad practice if you want a stable sytem.

Johan

"eeh" <eehobbyist@yahoo.com.hk> wrote in message
news:1138634286.076967.253360@g14g2000cwa.googlegroups.com...
> OK after adding 10uF decoupling cap at 3.3.V supply
>

What size cap did you have there before? And another question - what sort 
of power supply are you using - better stated maybe, how long are the 
wires that bring power to microcontroller?

Neccessary filtering for a power supply always seems questionable.

Hul

eeh <eehobbyist@yahoo.com.hk> wrote:
> OK after adding 10uF decoupling cap at 3.3.V supply

Hul Tytus wrote:
> What size cap did you have there before? And another question - what sort
> of power supply are you using - better stated maybe, how long are the
> wires that bring power to microcontroller?
>
> Neccessary filtering for a power supply always seems questionable.
>
> Hul

Before that I used only two 0.1uF at the regulator. The board is small
which is about 3 inches x 2 inches. The power supply is dc supply (5V)
and the voltage passes a HT7533 linear regulator.