Ramp DAC on F28027

[Toby 0]

Hi Folks

 

The documentation for the comparator block on the F28027 (SPRUGE5) mentions the ability to have the reference DAC produce a ramp. It goes on to describe several registers that are used to set this up, DACCTL for example.

However I have not been able to find any other mention of this ability or these registers in any other (device-relevant) document or include file.

Is this feature actually implemented? Which peripheral header file should include the relevant register structure? or what register structure are they under?

Thanks

 

Note: I have posted a question to the same effect on the e2e forums but no-one answered... usually not a good sign!

[TI_Trey 38]

Toby,

 

I'm not an expert on the comparators, but I'll do my best to answer your question.

 

I too have been unable to find these registers in the normal header file structures, but I was able to find the DACVAL register in the comparator structures.  I believe what is going on here is that the ramp generator was a feature that was not documented for a long while.  Someone eventually got time to test and document this feature and it was probably added to the device after the device was released.  While it was added in the documentation, the necessary software updates probably got lost and hence you don't see the register in the header files.

 

That said, the ramp generator is included in the new comparator drivers which are currently in controlSUITE.  You'll see its defined in f2802x_common/include/comp.h, but there are no driver APIs to use it.  You ought to be able to easily write some drivers for yourself in comp.c that access these registers as you please.

 

I'll follow up on this and ensure this is true and if so file a bug to get this fixed.  Thanks for bringing this to my attention.

[TI_Trey 38]

I just confirmed with the guy who brought up the ramp generator, this feature is here and was documented after the part was released.  Everything above is true.

[Toby 0]

Hi Trey,

Thanks a mill for getting back so quick!

 

So essentially what I need to do is alter the COMP_REGS struct in my version of the DSP2802x_Comp.h, adding the child unions/structs where needed, to match the _COMP_Obj_ in the comp.h you mentioned?

 

Looking back through the DSP2802x_GlobalVariableDefs.c and DSP2802x_Headers_nonBIOS.cmd it seems the correct allocation and placement is already taken care of. But is there anywhere else I would need to make amendments that you might know?

I dont see any mention of comparators at all in PeripheralAddress_ASM.h, for example, so I guess nothing needs to change there?

 

Thanks again

[Toby 0]

Trey

so following on with what I outlined, and in case anyone else looking for the same thing stumbles across this post, I will document what I am doing here. Here is what I added to the DSP2802x_Comp.h file of the version 128 device support header includes:

 

addition of the below struct and union (before the declaration of the struct COMP_REGS):

struct DACCTL_BITS {                // bit       description
	Uint16   DACSOURCE:1;       // 0         DAC source control
	Uint16   RAMPSOURCE:4;      // 1:4       Ramp generator source sync select
	Uint16   rsvd1:9;           // 5:13      reserved
	Uint16   FREE:2;            // 14:15     Emulation mode behaviour
};

union DACCTL_REG {
	Uint16                         all;
	struct DACCTL_BITS             bit;
};

Then replaced the struct COMP_REGS with the following amended version:

struct COMP_REGS {
    union  COMPCTL_REG         COMPCTL;
    Uint16                     rsvd1;
    union  COMPSTS_REG         COMPSTS;
    Uint16                     rsvd2;
    union DACCTL_REG           DACCTL;
    Uint16                     rsvd3;
    union DACVAL_REG           DACVAL;
    Uint16                     rsvd4;
    Uint16                     RAMPMAXREF_ACTIVE;
    Uint16                     rsvd5;
    Uint16                     RAMPMAXREF_SHADOW;
    Uint16                     rsvd6;
    Uint16                     RAMPDECVAL_ACTIVE;
    Uint16                     rsvd7;
    Uint16                     RAMPDECVAL_SHADOW;
    Uint16                     rsvd8;
    Uint16                     RAMPSTS;
};

With this added, and a test reference to one of the bits in the new structs I rebuilt my project. I hasnt thrown any errors or warnings at me, however the C variable reference that I tested with "Comp1Regs.DACCTL.bit.DACSOURCE = 0;" the child member names text have not turned blue as they do with other struct and union member references. also if I "ctrl+click" on any of the member names, e.g. DACCTL,  the IDE says "Could not find symbol "DACCTL" in index...

Does this mean my changes have not actually had any effect? What else would I need to do?

Thanks

[TI_Trey 38]

Hi Trey,

Thanks a mill for getting back so quick!

 

So essentially what I need to do is alter the COMP_REGS struct in my version of the DSP2802x_Comp.h, adding the child unions/structs where needed, to match the _COMP_Obj_ in the comp.h you mentioned?

 

Looking back through the DSP2802x_GlobalVariableDefs.c and DSP2802x_Headers_nonBIOS.cmd it seems the correct allocation and placement is already taken care of. But is there anywhere else I would need to make amendments that you might know?

I dont see any mention of comparators at all in PeripheralAddress_ASM.h, for example, so I guess nothing needs to change there?

 

Thanks again

 

No Problem, always happy to help out.  Sorry no one got to your e2e post sooner.  I'll give Devin a poke in the ribs

Your work statement is correct, but I'm not aware of any PeripheralAddress_ASM.h...where did you find this? 

 

 

Trey

so following on with what I outlined, and in case anyone else looking for the same thing stumbles across this post, I will document what I am doing here. Here is what I added to the DSP2802x_Comp.h file of the version 128 device support header includes:

 

addition of the below struct and union (before the declaration of the struct COMP_REGS):

struct DACCTL_BITS {                // bit       description
	Uint16   DACSOURCE:1;       // 0         DAC source control
	Uint16   RAMPSOURCE:4;      // 1:4       Ramp generator source sync select
	Uint16   rsvd1:9;           // 5:13      reserved
	Uint16   FREE:2;            // 14:15     Emulation mode behaviour
};

union DACCTL_REG {
	Uint16                         all;
	struct DACCTL_BITS             bit;
};

Then replaced the struct COMP_REGS with the following amended version:

struct COMP_REGS {
    union  COMPCTL_REG         COMPCTL;
    Uint16                     rsvd1;
    union  COMPSTS_REG         COMPSTS;
    Uint16                     rsvd2;
    union DACCTL_REG           DACCTL;
    Uint16                     rsvd3;
    union DACVAL_REG           DACVAL;
    Uint16                     rsvd4;
    Uint16                     RAMPMAXREF_ACTIVE;
    Uint16                     rsvd5;
    Uint16                     RAMPMAXREF_SHADOW;
    Uint16                     rsvd6;
    Uint16                     RAMPDECVAL_ACTIVE;
    Uint16                     rsvd7;
    Uint16                     RAMPDECVAL_SHADOW;
    Uint16                     rsvd8;
    Uint16                     RAMPSTS;
};

With this added, and a test reference to one of the bits in the new structs I rebuilt my project. I hasnt thrown any errors or warnings at me, however the C variable reference that I tested with "Comp1Regs.DACCTL.bit.DACSOURCE = 0;" the child member names text have not turned blue as they do with other struct and union member references. also if I "ctrl+click" on any of the member names, e.g. DACCTL,  the IDE says "Could not find symbol "DACCTL" in index...

Does this mean my changes have not actually had any effect? What else would I need to do?

Thanks

 

This is probably just the indexer in CCS being silly.  It basically goes and parses everything in a project so that it can highlight and provide assistance on known symbols.  In my experience this piece of software has problems, so I take it with a grain of salt.  Try compiling, if you don't get compile errors you're good.  Remember you may need to EALLOW to write some of these registers.

[Toby 0]

Your work statement is correct, but I'm not aware of any PeripheralAddress_ASM.h...where did you find this? 

I found this in "development_kits/~SupportFiles/F2802x_headers/" along with the PeripheralHeaderIncludes.h file.

 

I compiled, loaded and ran the program without errors - though have not yet actually tested functionality

I tried restarting CCS (and my machine) to see if this would induce the indexer to re-index the _Comp header file, but no change, never mind.

Thanks for the EALLOW mention, hadn't thought about that!

Cheers

 

P.S. I'll cross-post my solution to the e2e for anyone looking for a solution there also

 

P.P.S. Have somewhat confirmed my changes by comparing the F2803x _Comp.h (as Devin suggested) in which the ramp registers ARE defined, and also has no mention in the relevant PeripheralAddress_ASM.h so I guess I dont need to add anything there.

 

Also fixed the indexer issue by 1) exporting my preferences 2) restarted CCS with the -clean arg, then closed CCS again 3) Cleaned my workspace 4) Re-opened CCS and imported my preferences and project (had to re-setup my perspectives also). 5) Bingo!

Instructions for the steps can be found on the TI wiki here. Step 2 is probably redundant but I tried it just to be sure!

 

Also, on comparison to F2803x header I changed my DAC_CTL bit 14:15 from FREE to FREE_SOFT