PLL disabled in T2081 custom board

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PLL disabled in T2081 custom board

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Contributor III

I have a custom board with sys_clk = 66.66 MHz, ddr_clk=66.6MHz.

And Hard coded RCW is used for board bring up as we dont have programmed flash yet.

Through scope we have seen that the T2081 has come out of Reset power on sequence.

1. But i still get in PLL status registers "PLL disabled"

2. No output at "clk_out" even  when configured proper clock domain control status register is programmed?

3. I am able to alter the register contents, toggled GPIO, able to program CPC RAM, Transmitted data on UART then why it shows PLL disabled?

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NXP TechSupport
NXP TechSupport

1) Which exactly RCW is used?

2) Have you provided SerDes reference clocks? What are their frequencies?

3) What are values of the registers showing the "PLL disabled"?

4) What you have done to output the CLK_OUT?

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Contributor III

1. POR Hard coded RCW used "0x1001 1101" used with sys_clk= ddr_clk=66.67 MHz option as per reference manual 

2. SERDES reference clock we are not using, disabled it. 

3.Clocking_PLLCnGSR  register shows PLL disabled

4. Programmed 15th bit of "Clocking_CLKPCSR"to have output at clk_out

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NXP TechSupport
NXP TechSupport

Please program a valid RCW corresponding to your configuration into a flash and test.

The issue can be connected with the hard-coded RCW settings where several SerDes PLLs are enabled - i.e. valid SerDes reference clocks must be applied.

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Contributor III

Thanks Fedor,

Plese look into the snap of the clock status register.

Clocking_PLLCnGSR =0x80000000. Showing PLL disabled.

1. Does Clocking_PLLCnGSR show status of  SERDES PLLs? (Clocking_PLLCnGSR shows the PLL status of PLL1 and PLL2 of CGA only i thought as per clocking diagram in page 222 of T2080 reference manual )

2. Where are SERDES PLLs located? Is it inside SERDES module inside T2080?

3. I am giving Hard Coded RCW.  Can i disable the SERDES PLL through JTAG configuration file (to overwrite hard coded RCW )

 

4. If SERDES PLLs are powered down, wil it still check for proper SERDES REFerence input clocks?

Capture_clk_status.PNG

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NXP TechSupport
NXP TechSupport

Please program a valid RCW corresponding to your configuration into a flash and test.

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