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LMX2492 ,How to set " MUXOUT=Output R divide/2"

user4336308
Prodigy 70 points
Other Parts Discussed in Thread: LMX2492, CODELOADER

I am just now starting to use LMX2492.

I use CPU=MicroChip 12F1822 to control it.

Now I can control "PowerOn (R2=0x01)".

So next step is  to test  "PLL_R".

Test condition is next.

OSCin=100MHz 0dBm , PLL_R=5, MUXout=Output R divide/2 ,PLL_R_DIFF=0, OSC_2x=0

 ====> check  Muxout= 10MHz  using oscilloscope.

Program step is next.   (Another Rxx  are  "POR"  value.)

1. set " PowerOn"  R2=0x01      I think Rxx ="POR" value here.

2. set  "MUXout"    R39=0x82    MUXout_MUX(4:0)=R divide/2=16  , MUXout_PIN(2:0)=2

3. set  "PLL-R"      R25=0x05     PLL_R(7:0)=5 

Result      I can't  get  10MHz ,  no-pulse(DC level)

Where is wrong ?

  • 0
    TI__Guru** 107780 points

    Hi there,

    with your configuration, I can make my board output 10MHz clock at MUXout pin. I use codeloader to control the board. my program sequence is as follow:

    1. power up the device

    2. program R2 --> R39 --> R25

    Maybe you need to check the uwire waveform to see if you have program the device correctly.

  • 0 in reply to Noel Fung
    Prodigy 70 points

    Hi

    Mant thanks  for your quick reply.

    This is the waveform of  DATA/CLOCK/LE  for  R39 and R25.

  • 0 in reply to user4336308
    Prodigy 70 points
    Hi

    I noticed my mistake R25 in the waveform.
    PLL_R = 50 (MUX_out=1MHz) -------->5(MUX_out=10MHz)
    R25 = 0x001932 -----------> 0x001905
  • 0 in reply to user4336308
    TI__Mastermind 28001 points
    Aosan,
    Depending on the power on defaults just leaves one more degree of unknown. For instance, the POWERDOWN register POR default in the datasheet is stated as 0x00. State 0 for POWERDOWN is for the device to be poweed down. So this could likely be the isue.
    REgards,Dean
  • 0 in reply to Dean Banerjee
    Prodigy 70 points
    Hi Dean
    Many thanks for your quick reply.
    My current program is R2-->R39-->R25 .
    But additional Delay is needed ? R2---->Delay---->R39---->R25.

    Anyway, I will study "codeloader" style.
    I already downloaded it, and testing it .

    If select_device=LMX2492 , "codeloader" stopped program.
    Another device is no problem.
    Could you solve this ?
  • 0 in reply to user4336308
    TI__Mastermind 28001 points
    Aosan,
    This must be some windows bug as I don't see it happen to me. Anyways, the LMX2492 has a flex gui, which is probably the issue. Try ths... Before you load the LMX2492, load a different part and go to options-> enable flex scripts and ensure that it is disabled. Hopefully this works.
    If this doesn't work, you can go to the install directory and open the LM2492.ini file and search for [FLEXES] and change the count from 0 to 1. Note that if you installed CodeLoader in the Program files directlry, windows will fight you with the "Virtual Store" and allow you to change it, but it actualy uses another file in some other secret directlry.
    Regards,Dean
  • 0 in reply to Dean Banerjee
    Prodigy 70 points
    Hi Dean
    I checked my CodeLoader FLEX condition.
    1. enable flex scripts = disable
    2. FLEXES count = 1

    My PC is OS=win7 pro 32bit, this PC /OS can't accept LMX2492.
    So I tested another old PC with OS=XP and accepted LMX2492.
    Now I am starting to control LMX2492 using CodeLoader.
    Regards
  • 0 in reply to user4336308
    Prodigy 70 points

    Hi  Dean, Noel

    Now  I can control  LMX2492  using CodeLoader  under  OS=XP.

    Next is  the control  wave (R2--->Delay--->R39---->R25).

    But  still I can't  get  10MHz  from  MUXout.

    Regards

  • 0 in reply to user4336308
    TI__Guru** 107780 points

    hi Aosan,

    it seems that you use the BurstMode but in "Loop" mode. Click the Loop button once to change it to Single, then the three registers will only be written once.

  • 0 in reply to Noel Fung
    Prodigy 70 points
    Hi Noel , Dean

    Good news !!
    Now I got MUXout=10MHz.
    It was hardware matter , not software.
    22pin=Vcp was open , this is the reason.
    Many thanks for your good support.
    Regards