Dear RandyP:
Thank you very much for your help, and you are very right. :) Now I am very sure that my problem is resulted from the reset of DSP IC.
My DSP IC is TMS320C6713BZDP-225. Its top mask is the following.
TMS320C6713BZDP
C20-25P01R8
0675456 E1
its core power is 1.2V, and I give it the right voltage. I am in China, the location of the 'instruction on the web" is a chinese forum.
http://bbs.ednchina.com/FORUM_POST_29_86609_0.HTM?jumpto=view_welcomead_forum_1390266273804
The above is the link.
Now, I think my reset circuit is defective. It generates reset signal only from a button. Reset pin remains high level when board powers on, and reset signal must be send manually.
The above is my reset circuit, I took the picture by my cellphone, I am sorry for the inconvenience.
The above two are the connection of configuration pins, Can you help me check them? Thank you!
My reset circuit can not work when board powers on. The output of clkout2 is unstable after power on and before reset.the yellow one is the signal on reset pin, and green one is the output of clkout2.
the output of clkout2 is unstable.
After IC is reset by button, clkout2 remains low level. PLL of DSP may not work, so the whole IC has no clock internally. I think that befor reset the dsp IC is in uncertainty. Therefore output of PLL is unstable.
I tested my board again, and found an interesting thing. The reset signal generated by button can not work, but when I used a metal wire to touch the reset pin after button reset, to my surprise, my dsp IC were reset and worked fine. JTAG could be used too.
I measured the reset pin while metal wire touched the pin, and found that it produced a oscillating signal. It can reset dsp IC effectively. Then, I connected reset pin to the output of a signal generator, which produced a 3.3V pulse. I thought it should be a prefect reset signal, but it can not work too.
In the test, I found that touching nearby ground also can reset the IC effectively.
the yellow one shows the signal on reset pin when I touch nearby ground, and green one is the output of clkout2. Before touching PLL has no output, and after that PLL works. Therefore, dsp IC works.
This is the enlargement of signal actions when I touch nearby ground.
the yellow one shows the signal on reset pin when I touch reset pin, and green one is the output of clkout2. The reset signal resulted is good, and PLL works.
In above picture, I touched the reset pin. The reset signal resulted was very bad, but it could reset dsp IC too. Then PLL worked, and the whole dsp IC worked. Can you explain it to me? Thank you!
It is said that reset signal generated from button always has some glitches, but In above pictures reset signal resulted from touching has glitches too. however it works. can you tell me which conditions the reset signal needs to meet? or when I touched the reset pin which conditions were meet?
I think I need a need a new reset circuit to reset IC when power on. I should use a reset IC from TI, and there should be lots of mature solutions for dsp reset. Can you give me an advice?
Thank you very much!
Sincerely
Gong yuwei