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LMX2492: Flat ramp

Jason Tandy
Prodigy 80 points

Part Number: LMX2492
Other Parts Discussed in Thread: CODELOADER

Dear Ti,

I am setting up a two ramp example, sweeping up and down in frequency.

Using code loader:

The second ramp stays at the same frequency rather than sweeping back to the start frequency.

I hit return in one of the parameters, with out changing the value and then it starts to work as expected.

Dumping the registers in both cases shows no difference in values.

What is happening?

I get this on the eval board.

On my board, I have not been able to get the second ramp to sweep.

I would upload the images, but can't get it to work in this window.

Thanks, Jason.

Thanks, Jason.

  • 0
    TI__Expert 5370 points
    Dear Jason,

    I would start by upgrading your software to TiCS PRO available on ti.com. It might be the root cause of your issue.

    Regards, Simon.
  • 0 in reply to Simon Damphousse
    Prodigy 80 points

    Thanks Simon,

    I will try that at some point.

    But I am seeing this on my own board, which does not use TI software, so I don't think it is just that.  Any other thoughts

    Regards, Jason.

    7536.flat top.pdf

  • 0 in reply to Jason Tandy
    TI__Mastermind 28031 points

    Jason,

    If I understand correctly, you get stuck on the last ramp and it doesn't repeat, but then you press enter and then it works on CodeLoader.  If this is the case, sounds like an update issue with CodeLoader.  Pressing enter programs a register, so perhaps what you were seeing on the ramp GUI on CodeLoader is not the same as what is on the registers.  TICSPro is much more elegant and much faster, especially for this ramp GUI.

    It sounds like you are also having issues with your software.  Assuming that you have the RAMPx_NEXT set up, the other thing to consider is the RAMP_EN bit.  The action of programming the RAMP_EN bit to 1 or programming the PLL_N value starts the ramp.  So the way it should be done is set up the ramp as it should be with RAMP_EN=0.  Then when everything is right, then set RAMP_EN=1.  Is it possible that you are setting up the ramp while RAMP_EN=1?

    Regards,
    Dean

  • 0 in reply to Dean Banerjee
    Prodigy 80 points

    Hi Dean,

    I have tried setting RAMP_EN to zero and then putting is back to a one, but the flat top is still there when it starts up again.  I am only changing this one register.

    So from power on,

    - I load the register set (R141 to R0) and get the flat top

    - RAMP_EN to zero

    - RAMP_EN to one

    flat top is still there.

    RAMPx_NEXT is set to '1' for RAMP0 and set to '0' for RAMP1.8078.flat top.pdf

    Regards, Jason.

  • 0 in reply to Jason Tandy
    TI__Mastermind 28031 points
    Jason,

    If I call the upward ramp "RAMP0" and the downward ramp "RAMP1" then it seems that in the non-desired flat top case is that RAMP0 is running as intended, but instead of RAMP1 downward ramping, it is not going at all. It is as if RAMP1_INC=0. Then when RAMP1 is finished, we see an abrupt correction back to the starting point of RAMP0, as would be the case if RAMP0_RST=1.

    I suspect that in CodeLoader, perhaps RAMP1 is not getting updated with teh gui until you press return.

    Regards,
    Dean
  • 0 in reply to Dean Banerjee
    Prodigy 80 points

    Dear Dean,

    I have found that CodeLoader is sending '0' data for the ramp increment and then correcting itself with a later set of transfers.  That explains the EVAL board behaviour.

    I still can't get the second ramp to ramp down on my board (I need the ramp down to improve the undershoot).

    Please see attached the register set being uploaded and a screen shot of the resultant wave form.  I may have changed the down ramp width by a single command in the screen shot compared to the file register set.

    The loading is done from R141 to R0.

    Any thoughts on why my down ramp is not working?

    Thanks, Jason.

    Fullscreen 1800MHz_dual.txt Download 
    R141,0x008D00
R140,0x008C00
R139,0x008B00
R138,0x008A00
R137,0x008900
R136,0x008800
R135,0x008700
R134,0x008600
R133,0x008500
R132,0x008400
R131,0x008300
R130,0x008200
R129,0x008100
R128,0x008000
R127,0x007F00
R126,0x007E00
R125,0x007D00
R124,0x007C00
R123,0x007B00
R122,0x007A00
R121,0x007900
R120,0x007800
R119,0x007700
R118,0x007600
R117,0x007500
R116,0x007400
R115,0x007300
R114,0x007200
R113,0x007100
R112,0x007000
R111,0x006F00
R110,0x006E00
R109,0x006D00
R108,0x006C00
R107,0x006B00
R106,0x006A00
R105,0x006900
R104,0x006800
R103,0x006700
R102,0x006600
R101,0x006500
R100,0x006400
R99,0x006300
R98,0x006202
R97,0x0061FA
R96,0x00603F
R95,0x005FFD
R94,0x005EF3
R93,0x005DB6
R92,0x005C24
R91,0x005B04
R90,0x005Ae2
R89,0x005900
R88,0x005800
R87,0x005768
R86,0x0056DB
R85,0x005500
R84,0x005400
R83,0x005300
R82,0x0052FF
R81,0x0051FF
R80,0x0050FF
R79,0x004FFE
R78,0x004EFF
R77,0x004DFF
R76,0x004CFF
R75,0x004BFE
R74,0x004A00
R73,0x004900
R72,0x004800
R71,0x004700
R70,0x004600
R69,0x004500
R68,0x0044FF
R67,0x0043FF
R66,0x0042FF
R65,0x0041FF
R64,0x004000
R63,0x003FFF
R62,0x003EFF
R61,0x003DFF
R60,0x003CFF
R59,0x003B00
R58,0x003A00
R57,0x003900
R56,0x00380F
R55,0x00376F
R54,0x00366F
R53,0x00350F
R52,0x00348F
R51,0x00330F
R50,0x00320F
R49,0x0031AF
R48,0x00300F
R47,0x002F4F
R46,0x002E30
R45,0x002D00
R44,0x002C00
R43,0x002B00
R42,0x002A00
R41,0x002900
R40,0x002800
R39,0x002752
R38,0x002618
R37,0x002510
R36,0x002408
R35,0x002341
R34,0x002204
R33,0x002120
R32,0x002000
R31,0x001F2E
R30,0x001E04
R29,0x001D00
R28,0x001C0A
R27,0x001B08
R26,0x001A00
R25,0x001902
R24,0x001800
R23,0x001703
R22,0x0016E8
R21,0x001500
R20,0x001400
R19,0x001300
R18,0x00122C
R17,0x001100
R16,0x001024
R15,0x000F00
R14,0x000E00
R13,0x000D00
R12,0x000C00
R11,0x000B00
R10,0x000A00
R9,0x000900
R8,0x000800
R7,0x000700
R6,0x000600
R5,0x000500
R4,0x000400
R3,0x000300
R2,0x000201
R1,0x000100
R0,0x000018

  • 0 in reply to Jason Tandy
    Prodigy 80 points

    Today I have repeated the flat top issue with the TICS Pro software on the EVAL board and currently am unable to clear it.

    Please see below images and the register set used.

    There must be something I am missing?


    Fullscreen EVAL flat top HexRegisterValues.txt Download 
    R141	0x008D00
R140	0x008C00
R139	0x008B00
R138	0x008A00
R137	0x008900
R136	0x008800
R135	0x008700
R134	0x008600
R133	0x008527
R132	0x008410
R131	0x008300
R130	0x008200
R129	0x008100
R128	0x008000
R127	0x007F00
R126	0x007E27
R125	0x007D10
R124	0x007C00
R123	0x007B00
R122	0x007A00
R121	0x007900
R120	0x007800
R119	0x007727
R118	0x007610
R117	0x007500
R116	0x007400
R115	0x007300
R114	0x007200
R113	0x007100
R112	0x007027
R111	0x006F10
R110	0x006E00
R109	0x006D00
R108	0x006C00
R107	0x006B00
R106	0x006A00
R105	0x006927
R104	0x006810
R103	0x00673F
R102	0x0066FF
R101	0x0065EC
R100	0x006457
R99	0x006340
R98	0x006227
R97	0x006110
R96	0x006000
R95	0x005F00
R94	0x005E06
R93	0x005D8E
R92	0x005C24
R91	0x005B27
R90	0x005A10
R89	0x005900
R88	0x005800
R87	0x00570D
R86	0x00561B
R85	0x005500
R84	0x005400
R83	0x005300
R82	0x005218
R81	0x005100
R80	0x005000
R79	0x004F00
R78	0x004E7A
R77	0x004D00
R76	0x004C00
R75	0x004B00
R74	0x004A00
R73	0x004900
R72	0x004800
R71	0x004700
R70	0x004600
R69	0x004500
R68	0x00447E
R67	0x004300
R66	0x004200
R65	0x004100
R64	0x004000
R63	0x003F03
R62	0x003E00
R61	0x003D00
R60	0x003C00
R59	0x003B00
R58	0x003A01
R57	0x003900
R45	0x002D00
R44	0x002C00
R43	0x002B00
R42	0x002A00
R41	0x002900
R40	0x002800
R39	0x002752
R38	0x002618
R37	0x002510
R36	0x002408
R35	0x002341
R34	0x002204
R33	0x002120
R32	0x002000
R31	0x001F32
R30	0x001E0A
R29	0x001D00
R28	0x001C1F
R27	0x001B08
R26	0x001A00
R25	0x001901
R24	0x001800
R23	0x001703
R22	0x0016E8
R21	0x001500
R20	0x001400
R19	0x001300
R18	0x00122C
R17	0x001100
R16	0x001060
R15	0x000F00
R14	0x000E00
R13	0x000D00
R12	0x000C00
R11	0x000B00
R10	0x000A00
R9	0x000900
R8	0x000800
R7	0x000700
R6	0x000600
R5	0x000500
R4	0x000400
R3	0x000300
R2	0x000201
R1	0x000100
R0	0x000018

  • 0 in reply to Jason Tandy
    Prodigy 80 points
    Looks like the RAMP_LIMIT_LOW and RAMP_LIMIT_HIGH registers are getting bad values. More to come ...
  • 0 in reply to Jason Tandy
    TI__Mastermind 28031 points

    Jason,

    OK,  I'll wait for your response. 

    Regards,

    Dean

  • 0 in reply to Dean Banerjee
    Prodigy 80 points

    I have got the circuit performing as I expect.

    I used the CodeLoader program to generate a default file with settings that worked on the EVAL board and used this to set up my board.  Somewhere along the line the RAMP_LIMIT_LOW and _HIGH  registers were changed from there power on reset values.  This could stop the negative ramp I was after from working.  Changing the registers back to their power on value makes the ramp work.  These registers would appear to be changed when loading default configurations in CodeLoader and TICS Pro, leading to my confusion.  I believe that somehow CodeLoader changes these registers, so sometimes the negative ramp worked and sometimes it didn't.  I guess the TICS Pro Default Configuration file can have a similar effect.

    Regards, Jason.