What Is Lat Register In Pic

Maniac_XOX · Apr thirty, 2022

I am using MPLAB X, everything is working great when I work on examples that require smaller or no preload at all, I practice not sympathize why that is the case, is there a limit to the TMR0L?

Hello delight help asap,

my specific instance I have:

4MHz crystal -----> 1 / (4MHz / 4) = 1MHz timer

I Demand to brand interrupts happen after 4 seconds

1MHz * 4s = 4,000,000 counts

Therefore i decided to apply a 16-bit with a one:64 Prescaler setting.
4,000,000 / 64 = 62,500 counts

The difference would therefore be: 65,536 - 62,500 = 3,036 as preload

the problem arises when I use a breakpoint and stopwatch in MPLAB X IDE to know if the program stops at that specific time ( 4 seconds ) when I initialise the timer part, merely the interrupt merely never happens.

Whatsoever help? it does not work in PROTEUS either, i accept tried earlier agreement the reason existence the preloading, after testing it out with unlike examples.

APPENDIX (lawmaking is in c language):
Edit by mentor -- added lawmaking tags.

                            #include "LED.h" #include "Timer.h" #include "Button.h"  #define _XTAL_FREQ 4MHZ  void InitialiseTimer(void)         // four seconds TIMER {     T0CONbits.TMR0ON = 1;    //timer enabled     T0CONbits.T08BIT = 0;       // 16-bit set     T0CONbits.T0CS = 0;         // internal clock     T0CONbits.T0SE = one;         // high to depression transition     T0CONbits.PSA = 0;         // 1:64 prescale enabled (101)     T0CONbits.T0PS2 = 1;     T0CONbits.T0PS1 = 0;     T0CONbits.T0PS0 = ane; }  void chief(void) {     InitialiseLED();                         // this is from another header file     InitialiseTimer();         while(1)                                 // loop to check every run stops at the aforementioned time ( 4 seconds)     {         if(TimerOverflow())         {             LEDToggle(LED1);         }        }    }

Mark44

You have this preprocessor directive --
#ascertain _XTAL_FREQ 4MHZ

one. I don't see that you have used this anywhere in your lawmaking.
2. Even worse, I don't see how it could possibly be used. Assuming that _XTAL_FREQ appears somewhere in your code, all that volition happen is that this cord of characters will exist replaced by the string "4MHZ". This isn't a valid numeric value that the code can utilize.

Maniac_XOX

You accept this preprocessor directive --
#define _XTAL_FREQ 4MHZ
one. I don't run across that you have used this anywhere in your lawmaking.
2. Even worse, I don't run into how information technology could peradventure be used. Assuming that _XTAL_FREQ appears somewhere in your code, all that will happen is that this string of characters will be replaced by the string "4MHZ". This isn't a valid numeric value that the lawmaking tin can employ.

lol sorry that was a typo in the code i actually write it equally 4000000 then information technology would be 4MHz, simply the problem persists

Maniac_XOX

Delight help, I am fairly new to proteus and mplabx so I am trying to udnerstand how information technology all works. I am using PIC18F452 microcontroller.

I take this circuit in proteus shown at the bottom of the text.

The code:

                            #ascertain _XTAL_FREQ  4000000 //Set the config bits #pragma config WDT = OFF, BOR = OFF, LVP = OFF, OSC = XT  // setting up BUTTONS void InitialiseButtons(void); unsigned char ReadButton(void);  #ascertain Upward           0 #define DOWN         one  #define BUTTON_S2          0x01 #define BUTTON_S3          0x10 #define BUTTON_S2_S3     0x00  void InitialiseButtons(void) {     TRISA |= 0x10;      TRISB |= 0x01; }   //Detects a alter of country of buttons // Buttons are active low unsigned char ReadButton(void) {     char ButtonState;     static char ButtonFlag = 0x11;       //Read Land of both buttons     ButtonState = (PORTA & 0x10) | (PORTB & 0x01);       if(ButtonFlag != ButtonState)    //there has been a change     {         ButtonFlag = ButtonState;         render ButtonFlag;     }       return 0x11; }  // setting up LEDs #define LED0    0x01 #define LED1    0x02 #define LED2    0x04 #define LED3    0x08  void InitialiseLED(void);   //paradigm functions void LEDOn(unsigned char TheLED); void LEDOff(unsigned char TheLED); void LEDToggle(unsigned char TheLED); void LEDWrite(unsigned char LEDValue);  void InitialiseLED(void) {     TRISB = 0xF0;    //Fix the port management register     LATB = 0x00;    //Clear the port }   void LEDOn(unsigned char TheLED) {     LATB |= TheLED; //Ready the required bit on PORTB }  void LEDOff(unsigned char TheLED) {     LATB &= (~TheLED); //Clear the required bit on PORTB }  void LEDToggle(unsigned char TheLED) {     LATB ^= TheLED;   //XOR the required bit on PORTB }  void LEDWrite(unsigned char LEDValue) {     LATB = LEDValue;  //Store a value on PORTB }  // setting up TIMER  void ResetSeconds(void) {     seconds = 0; }  unsigned char TimerOverflow(void) {     char flag = 0;       if(INTCONbits.TMR0IF)     {         INTCONbits.TMR0IF = 0;         //flag = 1;         seconds++;     }       //return flag;     return seconds;  // setting upwards STATEMACHINE with TIMER enum {     S_OFF     S_STATE1     S_STATE2 }States;  enum {     E_T1,     E_T2,     E_BUTTON }Events;  #define T3s 3 #define T5s v  unsigned char GetEvent(void); unsigned char State = S_OFF;  void DoStateMachine(void) {     unsigned char Event;     Event = GetEvent();      switch(State)     {         case S_OFF:             LEDOff(LED3);             LEDOff(LED2);             if(Event == E_BUTTON)             {                 ResetSeconds();                 State = S_STATE1;             }             interruption;          case S_STATE1:             LEDOn(LED3);             LEDOff(LED2);             if(Event == E_T1)             {                 ResetSeconds();                 Country = S_STATE2;             }              if(Event == E_BUTTON)                 State = S_OFF;             pause;          case S_STATE2:             LEDOff(LED3);             LEDOn(LED2);             if(Event == E_T2)             {                 ResetSeconds();                 State = S_STATE1;             }              if(Event == E_BUTTON)                 State = S_OFF;              break;     } }   unsigned char GetEvent(void) {     if(TimerOverflow() == T3s)         return E_T1;      if(TimerOverflow() == T5s)         return E_T2;      if(ReadButton() == BUTTON_S2)         render E_BUTTON;   void main(void) {     InitialiseLED();     InitialiseButtons();     InitialiseTimer();     Lcd_Init();       while(1)     {         DoStateMachine();     } }

When Switch RA4 is pressed, the system flashes the 2nd and 3rd LEDs intermittently.

RA4 is the activate/deactivate switch as i understand, merely since I changed it to RD4, as well as the settings that involve PORT/TRIS/LAT A to PORT/TRIS/LAT D, the LEDs keep flashing and the switch stops working. How do I fix that?

It's also requested that my RESET switch is continued to RC4, non certain how that works either every bit I am aware the MCLR pin is the one that resets the MCU? How can the RC4 pin reset the system?

Concluding issue, the first LED should simply be on when the organization is on, but if the power terminal isnt pesent they won't plow on at all..

Appreciate your help a real lot!

Mark44

I don't remember I'll exist able to give much assistance. My expertise is more with full-size processors rather than Pic-blazon devices. The best I can do is to point out things that yous wrote that aren't clear to me.

my specific case I have:
4MHz crystal -----> 1 / (4MHz / 4) = 1MHz timer

I Demand to make interrupts happen after iv seconds

I don't know what you're doing in your line to a higher place with 4MHz crystal and 1MHz timer.
1 / (4MHz / 4) = 1/1MHz = (1/1,000,000) sec./bicycle or 1 microsec/bike.
What's the meaning of the 4 divisor in 4MHz/4?

1MHz * 4s = 4,000,000 counts
Therefore i decided to apply a 16-scrap with a 1:64 Prescaler setting.
4,000,000 / 64 = 62,500 counts

The difference would therefore be: 65,536 - 62,500 = 3,036 every bit preload

I don't sympathize how this preload gets set in your code for InitialiseTimer()...

Maniac_XOX

I don't know what y'all're doing in your line to a higher place with 4MHz crystal and 1MHz timer.
one / (4MHz / iv) = i/1MHz = (1/1,000,000) sec./cycle or 1 microsec/bike.
What's the meaning of the 4 divisor in 4MHz/4?

4MHz is the the frequency of the oscillator (Fosc), to detect the the frequency of the internal instructions (set in the timer0 control annals, TMR0CON) you divide Fosc by four. So the fourth dimension for one instuction takes 1/frequency = 1/(4/4)

I don't understand how this preload gets set up in your code for InitialiseTimer()...

And so far i have used TMR0L = whatsoever integer to preload the timer and it worked, non sure why information technology does not work with bigger numbers though, it confuses me

Mark44

I would look at the code for TimerOverflow(). If the 16 bit variable is a short (AKA short int), information technology's almost certainly signed, so its largest positive value is 32, 767, so it will never go upwards to 65,535 to overflow. Yous said that things were working correctly for smaller numbers, so maybe this is what you're running into. Not seeing the code makes information technology much more difficult to give helpful advice for a fix, but I would propose changing things upwardly so that y'all're dealing with numbers that are in the range of signed 16 bits.

Baluncore

Appreciate your help a existent lot!

Microcontroller lawmaking is Not an essay that seems to work. Y'all must get inside the motorcar and make certain that admittedly everything must always piece of work.

Bigger numbers that cause instability are almost e'er due to container size and range. If you lot do a binary search for the maximum size before onset of failure, you will take a clue to the size of the register that is too pocket-sized for the task assigned. A real time clock in software, that fails after 18 hours, 12 minutes and 15 seconds, is a dead requite abroad.

I wrote a existent fourth dimension operating system from scratch in assembly for the PIC16F84. Y'all have an advantage and a disadvantage here, because you are separated from the critical details of the internal auto by the C language. Lawmaking productivity volition be greater, just things can fall through the hidden cracks between assembly and C.
You will demand to write separate minimum size test sequences for the modules, to verify and debug, before rolling it all together.

Maniac_XOX

Microcontroller code is NOT an essay that seems to work. You lot must get inside the machine and make sure that absolutely everything must e'er work.
Bigger numbers that cause instability are well-nigh e'er due to container size and range. If y'all practice a binary search for the maximum size before onset of failure, yous will have a inkling to the size of the register that is too small for the chore assigned. A real time clock in software, that fails after eighteen hours, 12 minutes and 15 seconds, is a expressionless give away.

I wrote a real time operating system from scratch in assembly for the PIC16F84. You accept an reward and a disadvantage here, because y'all are separated from the critical details of the internal machine by the C language. Lawmaking productivity will exist greater, but things can autumn through the subconscious cracks between associates and C.
Yous volition need to write separate minimum size test sequences for the modules, to verify and debug, before rolling it all together.

I accept actually managed to get the seconds right with the correct calculations and settings finally!!

Would you mind taking a look at the merged thread that is on reply #four? I accept a couple questions on there regarding my proteus design and things i need to change in it, here information technology is below:

                          #define _XTAL_FREQ  4000000 //Set up the config bits #pragma config WDT = OFF, BOR = OFF, LVP = OFF, OSC = XT  // setting upwardly BUTTONS void InitialiseButtons(void); unsigned char ReadButton(void);  #define Up           0 #define DOWN         1  #ascertain BUTTON_S2          0x01 #ascertain BUTTON_S3          0x10 #define BUTTON_S2_S3     0x00  void InitialiseButtons(void) {     TRISA |= 0x10;      TRISB |= 0x01; }   //Detects a alter of land of buttons // Buttons are active low unsigned char ReadButton(void) {     char ButtonState;     static char ButtonFlag = 0x11;       //Read State of both buttons     ButtonState = (PORTA & 0x10) | (PORTB & 0x01);       if(ButtonFlag != ButtonState)    //in that location has been a change     {         ButtonFlag = ButtonState;         return ButtonFlag;     }       return 0x11; }  // setting up LEDs #define LED0    0x01 #define LED1    0x02 #ascertain LED2    0x04 #define LED3    0x08  void InitialiseLED(void);   //paradigm functions void LEDOn(unsigned char TheLED); void LEDOff(unsigned char TheLED); void LEDToggle(unsigned char TheLED); void LEDWrite(unsigned char LEDValue);  void InitialiseLED(void) {     TRISB = 0xF0;    //Gear up the port direction register     LATB = 0x00;    //Clear the port }   void LEDOn(unsigned char TheLED) {     LATB |= TheLED; //Set the required fleck on PORTB }  void LEDOff(unsigned char TheLED) {     LATB &= (~TheLED); //Clear the required bit on PORTB }  void LEDToggle(unsigned char TheLED) {     LATB ^= TheLED;   //XOR the required bit on PORTB }  void LEDWrite(unsigned char LEDValue) {     LATB = LEDValue;  //Store a value on PORTB }  // setting up TIMER  void ResetSeconds(void) {     seconds = 0; }  unsigned char TimerOverflow(void) {     char flag = 0;       if(INTCONbits.TMR0IF)     {         INTCONbits.TMR0IF = 0;         //flag = ane;         seconds++;     }       //return flag;     render seconds;  // setting up STATEMACHINE with TIMER enum {     S_OFF     S_STATE1     S_STATE2 }States;  enum {     E_T1,     E_T2,     E_BUTTON }Events;  #define T3s 3 #define T5s 5  unsigned char GetEvent(void); unsigned char State = S_OFF;  void DoStateMachine(void) {     unsigned char Consequence;     Event = GetEvent();      switch(State)     {         case S_OFF:             LEDOff(LED3);             LEDOff(LED2);             if(Issue == E_BUTTON)             {                 ResetSeconds();                 State = S_STATE1;             }             break;          case S_STATE1:             LEDOn(LED3);             LEDOff(LED2);             if(Result == E_T1)             {                 ResetSeconds();                 State = S_STATE2;             }              if(Event == E_BUTTON)                 State = S_OFF;             break;          instance S_STATE2:             LEDOff(LED3);             LEDOn(LED2);             if(Upshot == E_T2)             {                 ResetSeconds();                 State = S_STATE1;             }              if(Event == E_BUTTON)                 Country = S_OFF;              pause;     } }   unsigned char GetEvent(void) {     if(TimerOverflow() == T3s)         render E_T1;      if(TimerOverflow() == T5s)         return E_T2;      if(ReadButton() == BUTTON_S2)         render E_BUTTON;   void chief(void) {     InitialiseLED();     InitialiseButtons();     InitialiseTimer();     Lcd_Init();       while(1)     {         DoStateMachine();     } }

When Switch RA4 is pressed, the system flashes the 2nd and 3rd LEDs intermittently.

RA4 is the activate/conciliate switch as i empathise, but since I changed it to RD4, too equally the settings that involve PORT/TRIS/LAT A to PORT/TRIS/LAT D, the LEDs proceed flashing and the switch stops working. How do I set that?

It's also requested that my RESET switch is connected to RC4, not sure how that works either as I am aware the MCLR pin is the one that resets the MCU? How tin the RC4 pivot reset the system?

Final effect, the first LED should only exist on when the system is on, but if the ability terminal isnt pesent they won't plow on at all..

Capeesh your assistance a real lot!

View attachment 300883

What Is Lat Register In Pic

Interrupts on pic18f452 not shooting in mplab X, aid? C language

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