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21489 can't run with 25 MHz crystal , but 4 MHz was OK?

Question asked by LouisChiang on Jul 19, 2013
Latest reply on Aug 5, 2013 by LouisChiang

Hi:

 

I had made a new ADSP-21489 board with 25MHz crystal on DSP pin 24 & 25, and I couldn't use HPUSB-ICE to access it through JTAG port. But when I changed the crystal to 4MHz, I can run the example code "LedBlink" in the target board with ICE. What's wrong with my DSP board?

 

I also found the SDRAM clock out (SDQM) was not good, it seems not as stable as the ADSP-21489 EZ Board's same pin output. I can't measure the real output frequency, but EZ board was very clear 200MHz.

 

By the way, I tried to run other example code in 4MHz, it will stop when running the PLL access code.

 

My DSP board only used SDRAM, and some ADC/DAC, no SRAM, no FLASH, no watchdog, no temperature device.

No used pins was left floating.

VDDINT = 3.29V

VDDEXT = 1.09V

RESET pin = 3.29V

 

Is there anything I should pay attention to?

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