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PLL not locked, but clock outputs seem OK

Hi,

PLL is not locked on my FMC150 board, neither the PLL status bit in the register nor the pin.

I am using the firmware extracted from the BSP package. The PLL is not locked. But the CLK-to-FPGA clock is measuring 245MHz. It looks like the DAC clock is around 491MHz by scoping on R70/R71 resistor’s pad. And ADC clock is around 166MHz by checking CLK_AB on FPGA. I think they are the expected numbers.

  I have got the following readings from internal registers of CDCE device:
[0]                          0x683C025 0 (Hex)               
[1]                          0x6800027 1 (Hex)               
[2]                          0x8382000 2 (Hex)               
[3]                          0x6800000 3 (Hex)               
[4]                          0xE980000 4 (Hex)               
[5]                          0x6800000 5 (Hex)               
[6]                          0x6800000 6 (Hex)               
[7]                          0x8340000 7 (Hex)               
[8]                          0x6800009 8 (Hex)               
[9]                          0x680500C 9 (Hex)               
[10]                        0x08FC270 A (Hex)               
[11]                        0x8000040 B (Hex)
[12]                        0x60009B0 C (Hex)
Status4 INDET_AUX It indicates that a clock is present at AUX-input (Y9) , when set to 1 RAM(Read Only)
Status5 INDET_VCXO It indicates that a clock is present at VCXO-input , when set to 1 RAM(Read Only)
Status6 PLL_LOCK It indicates that the PLL is locked when set to 1 RAM(Read Only)
 
Then I calculated the dividers using the equation…
 
Fvcxo/Fref = P*N/(R*M)
 
Here with Fvcxo =  491.52MHz, Fref = 100MHz, P = 8, N = (575+1), R = 1, M = (624 + 1), both sides are not equal. N should be (3839+1) to make them equal. So I changed the initial coefficients for the firmware to configure the FMC150 board on reset. And then the register value at 0xA is  0x3BFC270A. But the PLL is still not locked.
 
Can anyone explain this?
 
Thanks

Thank you for your reply. But it seems the firmware does send it out an initialisation sequence at power-up reset...
Can you also point out where I can get the "Getting Started Guide"?
Dear Sir,


The firmware will not be operational before you actually run the software application, as per 4FM Getting Started Guide; The software configures the chip set in a way it can be used.


Best Regards,
Arnaud