Setting Register Value in C Code

[jay_dee]

Hi,
in the past I have manually set register bits by bit shifting in a C code component.
for example,
PIR1 = PIR1 & ~(1<<2); // Clear CCP1IF
PIE1 = PIE1 | 0x04; // Set CCP1IE

When robbing, bodging and checking against with C code examples from Microchip application notes, I see they use an easier to read method.
PIR1bits.CCP1IF = 0; // Clear CCP1 interrupt flag
PIE1bits.CCP1IE = 1; // Enable the CCP1 int

Can this method be used without issue in Flowcode C code components?
Obviously your register names have to be correct to avoid throwing a compile error!

[jay_dee]

In another project I also See, they use something similar in IF statements.
if (SSPSTATbits.D_nA) // If D_nA = 1 then TRUE
if (!SSPSTATbits.R_nW) //If R_nW = 0 then TRUE

Can something similar be used in a Normal FC IF Statement? Would it need just need FCV_ adding to it?
FlowCode IF componet = "FCV_SSPSTATbits.D_nA" // If D_nA = 1 then TRUE

or is there a similar method that works?
thanks, J.

[Steve-Matrix]

When robbing, bodging and checking against with C code examples from Microchip application notes, I see they use an easier to read method.
PIR1bits.CCP1IF = 0; // Clear CCP1 interrupt flag
PIE1bits.CCP1IE = 1; // Enable the CCP1 int

Can this method be used without issue in Flowcode C code components?

Yes, that should work fine. It will obviously not simulate though.

In another project I also See, they use something similar in IF statements.
if (SSPSTATbits.D_nA) // If D_nA = 1 then TRUE
if (!SSPSTATbits.R_nW) //If R_nW = 0 then TRUE

Can something similar be used in a Normal FC IF Statement? Would it need just need FCV_ adding to it?

No, not directly. You could first read the bit into a Flowcode variable in a C code icon and then use a decision icon on that variable:

FCV_MYVAR = SSPSTATbits.D_nA;

...then "if MyVar" in the decision.

Or you could customise the code of the decision icon and use C there directly.

[jay_dee]

Hi Steve,
If I have a FC LOCAL variable, inside a user macro. How would I reference this in C ?
Assuming "MyMacro" and Local Variable ".MyVar"

would something like FCV_MYVAR = SSPSTATbits.D_nA;
become
FCV_MYMACRO.MYVAR = SSPSTATbits.D_nA;
?? thanks, John.

[Steve-Matrix]

The short answer is FCL_MYVAR. The suffix for globals is "FCV_" and the suffix for locals is "FCL_".

In the C-code icons (which includes any other icons that have been customised), you can drag variables from the lists on the right onto the C code. When dropped, they will be added to the C code text with the appropriate C reference.

[jay_dee]

Hi,
this method of setting values in registers work well for me.
REGISTERNAMEbits.BITNAME
for example,
BRGCON2bits.SAM = 1; // Set the SAM bit to 1 in Register BRGCON2

However if a bit field is longer than one bit, how do I refer to the BitFields name?
Do I just refer to the lowest value bit, bit0? even though the bit field may be 2, 3, 6... bits in length?
i.e
REGISTERNAMEbits.BITNAME0
for example,
BRGCON1bits.BRP0 = 2 // Set the BRP bits to 2 in Register BRGCON1

Is this approach valid, it compiles but I'm debugging my own CAN INIT and just want to make sure this shortcut notation is not part of the problem.
Thanks, J.

[mnfisher]

The 'bits' refers to a bitfield

So for example OSCCONbits.ICRF = 0b101 would set three bits (ICRF<0..2> - on a sample PIC18F) would be my understanding - whereas OSCCONbits.ICRF0 would refer to a single bit.

Martin

[jay_dee]

Intersting and make sense but
if I use the Bitfield name the compiler throws an error. But 'BRGCON1bits.BRP0 = 1' will pass

3698: BRGCON1bits.BRP = 1;
^ (255) not a member of the struct/union ""
^ (182) illegal conversion between types
int -> volatile union S783

[mnfisher]

Odd - I've just tested with a PIC18F46K80 as the target and:

OSCCONbits.INTRF = 0b101;
BRGCON1bits.BRP = 0b10001;

Compiles okay - maybe been missed from the include for the MCU you are using?

The alternative is something like (assuming BRP is bits 0..4)

BRGCON1 = (BRGCON1 & 0b11100000) | DESIRED_BRP_VALUE; // Clear BRP then OR in new bits

Martin