Electronic – PIC warning 364 related to initialization of const

embeddedhi-tech-compilermicrocontrollermplabpic

There are no answers to this on the internet that I could find, and I've looked twice over the last 4 months.

In MPLab v8.88 using the Hi-Tech ANSI C Compiler, I have this line of code:

const   uint8 SUM_THRESHOLD_MIN = 15;   /* comment edited out   */

and I get the warning:

Warning [364] C:\*directory edited out* \ *filename_edited_out*.c; 273.35 attempt to modify object qualifed const

(excuse the edits, but I felt I should edit out personal yet superfluous details).

It is not my code, and I'd just use a #define, but others want to use a const (for those that don't know: using a const guarantees a proper typecast of a value, and can save you from some weird issues related to typecasting and data types; it's not my favorite way of doing it, but it's not a bad idea either).

There are several const initializations happening in the same block of code, and they all give me this warning. They are in a .c file, in a void function. I have other files with void functions where I initialize const uint8's and there are no warnings in those files. I searched globally, and found no other instance of the variable except where it gets used in the void function (so there aren't any issues with redefining or anything like that). To be clear, these const's are not part of any structure or anything strange, they are just declared in the void function in the .c file.

I have uint8 properly typedef'd, and not #define'd (see comments).

Can someone help me get rid of this warning?

EDIT:
If I paste one of the const uint8's into another .c file directly after a const uint16 that doesn't throw the error, like this:

const uint16 rate_bias_time_constant[NUM_RATE_CHANNELS][RATE_BIAS_STEP_MAX] = 
    {30,120,480,960,  300,120,180,240,  300,120,180,240 }; // comment edited out
const   uint8 SUM_THRESHOLD_MIN = 15;   /* comment edited out   */

I get warning 364 in this file for this const uint8 but not for the const uint16. If I change SUM_THRESHOLD_MIN from a uint8 to a uint16, I still get the warning. For completeness, if I change it from all uppercase to all lower case, I still get the warning.
If I change the line to, e.g.:

const uint8 SUM_THRESHOLD_MIN[2] = {15,2};  /* comment edited out   */

There is no warning.

Best Answer

I got it, and thanks so much for everyone's help!

The declarations that are not throwing warnings are either arrays, or they are declared static const uint8/16's. For some reason, the Hi-Tech C compiler is fine with const int/char's, const uint8/16's that are arrays, but not const uint8/16's unless declared as static const uint8/16.

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Programming dsPIC30F4011/13 on board dsPICDEM 2 with MPLAB ICD 2

You have to set the configuration bits. Near the end of the device's header file (line 5880 for dsPIC30F4013) is a listing of all the device's configuration bits that need to be set or cleared to ensure proper operation of the device, as well as code comments for how to do it.

For example:

_FOSC( XT & CSW_FSCM_OFF )  // Configure for external XT crystal oscillator, turn off clock switching and monitoring

The oscillator and watchdog timer configurations are very important.

EDIT: In your edited post you tried using the phase-locked loop option for the oscillator. You have to add the following code in your main routine in order to use an external oscillator + PLL:

/*
 *  Set up the PLL for full 60 MIPS operation (dsPIC33EP512MU810)
 *
 *  Fcy = Fin*K/2 --> 60MHz = 8MHz*K/2 --> K = 15
 *  K = M/(N2*N1) --> 15 = M/(N2*N1)   --> N2 = 2, N1 = 2, M = 60
 *  Fcy = 8MHz*15/2 = 60MHz
 *
 *  p. 164-171 datasheet
 */
void configPLL()
{
    PLLFBDbits.PLLDIV = 58; // M = 60
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Electronic – How to write and upload a LED blink program on a PIC (pic16f59)

The error message you get indicates a communication failure between the PicKit and the chip. It has nothing to do with the contents of your program. It would help if you showed the schematic of exactly what is around the PIC and how the PicKit is connected. Possible issues are:

Something is loading the PGC or PGD pin, which prevents the programmer from communicating.
Something is not allowing MCRL to be raised to the programming voltage. I didn't look up the programming spec for this chip, but Vpp can be as high as 13 V for some PICs.
No bypass cap accross Vdd and Vss.
Not all power and ground pins hooked up if this chip has multiple. Again, I didn't look up your specific PIC.
Too long a cable between the PicKit and the chip, which allows for crosstalk between PGC and PGD.

See my In-circuit Serial Programming paper for more detail and general demystification of the programming process.

On a separate topic, there are two flaws in your program. First you need to set RB1 as output since it wakes up as input. Second, you need to turn it off in the loop too if you want the LED to blink. Right now your program sets RB1 high and leaves it that way. If your chip has analog inputs, then you also have to make sure that RB1 is either not one of them or to explicitly switch it to a digital pin.

Best Answer

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Programming dsPIC30F4011/13 on board dsPICDEM 2 with MPLAB ICD 2

Electronic – How to write and upload a LED blink program on a PIC (pic16f59)

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