Hi Gene,
The crystal frequency is 25.000MHz on my ADSP-21262 board. I firstly made two
boards for test now. Both run fine without capacitors connected to the crystal.
I haven't tried other values yet. I think it has something to do with the
board, wire length and width, chip and crystal packages...etc. You may need to
try it out in your own condition.
In my situation, ICE TEST can still be successful even if VDSP fails to run,
reporting "Failed to halt processor...".
The power supply chip on my board is TI's LDO TPS70345. I am quite
disappointed at its noise, about 10-13mV on 1.2V core. But the DSP still seems
to work fine.
Hope it helps. Good luck!
Rongxi Lee
----- Original Message -----
From: "Gene-eng"
To:
Sent: Tuesday, May 09, 2006 1:44 AM
Subject: [adsp] Re: FW: Debug problem for ADSP-21262
> Rongxi,
>
> Please elaborate when you say "It failed to start if there were two 18pF
> capacitors connected between its crystal and ground." What crystal
> frequency and what capacitor values have you found to work without failure?
>
> We have been having problems with ADSP-21262's in production boards
> occasionally failing to boot (VDSP JTAG debugger can't even connect). We
> changed crystal capacitors to 18pf (as well as better 1.2V core supply
> improvements) and the failure rate is lower but still not 0%.
>
> Thanks,
> Gene
>
>> From: "phychem" p...@hit.edu.cn
>> Date: Sun May 7, 2006 6:22am(PDT)
>> Subject: Re: FW: Debug problem for ADSP-21262
>>
>> Hi!
>> Thank you Sergio and Todd. I tried overnight and solved the problem. I
>> removed the two 22pF capacitors from the DSP crystal and it works
>> fine...The same problem happened a few days ago when we were debugging a
>> board of ADuC7020.It failed to start if there were two 18pF capacitors
>> connected between its crystal and ground. It is quite strange rite?
>>
>> Regards,
>> Rongxi
>
