[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [avr-gcc-list] avrdude, ATMega128
From: |
Anton Erasmus |
Subject: |
Re: [avr-gcc-list] avrdude, ATMega128 |
Date: |
Sun, 05 Jun 2005 19:21:25 +0200 |
On 5 Jun 2005 at 14:45, Torsten Mohr wrote:
> Hi,
>
> > > The supply voltages look ok.
> > > PEN is connected to GND.
> >
> > This should be VCC. Not even JTAG programming works if this is GND.
>
> i just soldered some additional capacitors to the pcb i made. Just
> when i did this, the wire that held PEN to GND fell off.
>
> Now the program works and i see 2.5 V with the DMM on Port B (as
> expected) and i see the expected pattern on port D.
>
> Also, i soldered the additional capacitors off again and now it also
> works, i can erase and reprogram the device.
>
> I see two possibilities now:
>
> 1. PEN has to be left open (i understand the data sheet differently)
>
> 2. when i soldered the SMD capacitors i had bad contact on some pads
> and
> i fixed that when i soldered the additional capacitors.
>
>
> Any way, i wonder now why i can erase and reprogram the device even
> with PEN left open. According to the data sheet there is an internal
> pull-up and PEN needs to be pulled low during reset. On the PCB, PEN
> is now open and by that pulled high during reset. I measure 5V at
> PEN.
>
The way I interpret the stuff regarding PEN in the manual is that it's status is
latched at a reset. If high then one can program the device. If held low at
reset,
then it cannot be reprogrammed until it has been reset again.
Regards
Anton Erasmus--
A J Erasmus