[SOLVED] PIC16F877A MCLR CIRCUIT PROBLEM ? capacitance ?

[asking]

Hi,

i have pull-up the MCLR pin with 10K Resistor but its not working. When i power up the circuit without pickit3 from 5V DC Source. Circuit is not starting. But when i connected the negative terminal to the MCLR pin and then take it. Circuit Starts jUST Like Car Self start i am really confused which type of circuit is required to clear the Capacitive effect on MCLR Pin. The RC Circuit given in Datasheet did not helped. i used R1 as 10K and R2 as 1K but what should be the C ? its not given in datasheet. I tried with random capacitor but did not helped. So Please help me.

Thanks.

 

[PA3040]

Can we see your source code ?

 

[asking]

Here's the source code

// PIC16F877A Configuration Bit Settings

#include <xc.h>
#include <htc.h>
#include "stdint.h"

// #pragma config statements should prece_pinde project file includes.
// Use project enums instead of #define for ON and OFF.

// CONFIG
#pragma config FOSC = HS        // Oscillator Selection bits (HS oscillator)
#pragma config WDTE = OFF       // Watchdog Timer Enable bit (WDT disabled)
#pragma config PWRTE = OFF      // Power-up Timer Enable bit (PWRT disabled)
#pragma config BOREN = ON      // Brown-out Reset Enable bit (BOR disabled)
#pragma config LVP = OFF        // Low-Voltage (Single-Supply) In-Circuit Serial Programming Enable bit (RB3 is digital I/O, HV on MCLR must be used for programming)
#pragma config CPD = OFF        // Data EEPROM Memory Code Protection bit (Data EEPROM code protection off)
#pragma config WRT = OFF        // Flash Program Memory Write Enable bits (Write protection off; all program memory may be written to by EECON control)
#pragma config CP = OFF         // Flash Program Memory Code Protection bit (Code protection off)


#define	_XTAL_FREQ	20000000




#include "stdint.h"
/* Memory Map */
#define CONFIG      0x00
#define EN_AA       0x01
#define EN_RXADDR   0x02
#define SETUP_AW    0x03
#define SETUP_RETR  0x04
#define RF_CH       0x05
#define RF_SETUP    0x06
#define STATUS      0x07
#define OBSERVE_TX  0x08
#define CD          0x09
#define RX_ADDR_P0  0x0A
#define RX_ADDR_P1  0x0B
#define RX_ADDR_P2  0x0C
#define RX_ADDR_P3  0x0D
#define RX_ADDR_P4  0x0E
#define RX_ADDR_P5  0x0F
#define TX_ADDR     0x10
#define RX_PW_P0    0x11
#define RX_PW_P1    0x12
#define RX_PW_P2    0x13
#define RX_PW_P3    0x14
#define RX_PW_P4    0x15
#define RX_PW_P5    0x16
#define FIFO_STATUS 0x17
#define DYNPD       0x1C

/* Bit Mnemonics */

/* configuratio nregister */
#define MASK_RX_DR  6
#define MASK_TX_DS  5
#define MASK_MAX_RT 4
#define EN_CRC      3
#define CRCO        2
#define PWR_UP      1
#define PRIM_RX     0

/* enable auto acknowledgment */
#define ENAA_P5     5
#define ENAA_P4     4
#define ENAA_P3     3
#define ENAA_P2     2
#define ENAA_P1     1
#define ENAA_P0     0

/* enable rx addresses */
#define ERX_P5      5
#define ERX_P4      4
#define ERX_P3      3
#define ERX_P2      2
#define ERX_P1      1
#define ERX_P0      0

/* setup of address width */
#define AW          0 /* 2 bits */

/* setup of auto re-transmission */
#define ARD         4 /* 4 bits */
#define ARC         0 /* 4 bits */

/* RF setup register */
#define PLL_LOCK    4
#define RF_DR_HIGH  3
#define RF_PWR      1 /* 2 bits */

/* general status register */
#define RX_DR       6
#define TX_DS       5
#define MAX_RT      4
#define RX_P_NO     1 /* 3 bits */
#define TX_FULL     0

/* transmit observe register */
#define PLOS_CNT    4 /* 4 bits */
#define ARC_CNT     0 /* 4 bits */

/* fifo status */
#define TX_REUSE    6
#define FIFO_FULL   5
#define TX_EMPTY    4
#define RX_FULL     1
#define RX_EMPTY    0

/* dynamic length */
#define DPL_P0      0
#define DPL_P1      1
#define DPL_P2      2
#define DPL_P3      3
#define DPL_P4      4
#define DPL_P5      5

/* Instruction Mnemonics */
#define R_REGISTER    0x00 /* last 4 bits will indicate reg. address */
#define W_REGISTER    0x20 /* last 4 bits will indicate reg. address */
#define REGISTER_MASK 0x1F
#define R_RX_PAYLOAD  0x61
#define W_TX_PAYLOAD  0xA0
#define FLUSH_TX      0xE1
#define FLUSH_RX      0xE2
#define REUSE_TX_PL   0xE3
#define ACTIVATE      0x50
#define R_RX_PL_WID   0x60
#define NOP1          0xFF

#define nrf24_CONFIG ((1<<EN_CRC)|(0<<CRCO)) // (1 << MASK_RX_DR)|

/// hardware spi pin defined
#define LED_PIN      PORTCbits.RC0 // led test
#define CSN_PIN      PORTCbits.RC2//          //set port as output
#define ce_pin       PORTCbits.RC1         //set port as output
//#define SCK_Pin      PORTBbits.RB1        //set port as output
//#define Mosi_Pin     PORTBbits.RB2         //set port as output
//#define Miso_Pin     PORTBbits.RB3        //set port as input
#define HIGH         1
#define LOW          0
#define payload 1;




void SPI_init()
{
    SSPEN = 0;
    TRISC = 0;     //SCK
    CKE = 1;
    SSPCON = 0x01;  //CKP = 0, SCK = 1MHz
    SMP = 1;
    SSPEN = 1;
}


unsigned char SPI_transfer(unsigned char data)
{
    SSPBUF = data;       // Put command into SPI buffer
    while (!BF);         // Wait for the transfer to finish
    return SSPBUF;       // Save the read value
}




void nrf24_ce_pin_digitalwrite(uint8_t state)
{
if (state)
{
ce_pin = 1;
}
else
{
ce_pin = 0;
}
}


void nrf24_csn_digitalwrite(uint8_t state)
{
if (state)
{
CSN_PIN = 1;
}
else
{
CSN_PIN = 0;
}
}



/*
void nrf24_sck_digitalwrite(uint8_t state)
{
if (state)
{
SCK_Pin = 1;
}
else
{
SCK_Pin = 0;
}
}


void nrf24_mosi_digitalwrite( uint8_t state)
{
if (state)
{
Mosi_Pin = 1;
}
else
{
Mosi_Pin = 0;
}
}


*/


/* software spi routine 
uint8_t SPI_transfer(uint8_t tx)
{
     uint8_t i = 0;
     uint8_t rs = 0;

    nrf24_sck_digitalwrite(LOW);

    for(i=0;i<8;i++)
    {

        if(tx & 0x80) // msbit first spi standard
            nrf24_mosi_digitalwrite(HIGH);
        else
            nrf24_mosi_digitalwrite(LOW);
        nrf24_sck_digitalwrite(HIGH);
        tx = tx << 1;
        if(Miso_Pin == 1)
        {
            rs |= 0x01;
        }
        nrf24_sck_digitalwrite(LOW);
  		nrf24_mosi_digitalwrite(LOW);
    }
    return rs;
    
}
*/


/* send and rece_pinive multiple bytes over SPI */ // checked with mirf
void nrf24_transferSync(uint8_t  *dataout,uint8_t *datain,uint8_t len)
{
    uint8_t i;

    for(i=0;i<len;i++){
       datain[i] = SPI_transfer(dataout[i]);
    }
}


//send multiple bytes over SPI // checked with mirf
void nrf24_transmitSync(uint8_t *dataout,uint8_t len)
{
    uint8_t i;

    for(i=0;i<len;i++){
      SPI_transfer(dataout[i]);
    }
}

void nrf24_configRegister(uint8_t reg, uint8_t value)
{
    nrf24_csn_digitalwrite(LOW);
    SPI_transfer(W_REGISTER | (REGISTER_MASK & reg));
    SPI_transfer(value);
    nrf24_csn_digitalwrite(HIGH);
}

void nrf24_powerUpTx() // checked with mirf
{
   // PTX = 1;
	
    nrf24_configRegister(CONFIG,nrf24_CONFIG|((1<<PWR_UP)|(0<<PRIM_RX)));

}

void nrf24_init()
{
	TRISB = 0b00000000;
	TRISA = 0b00000000;
	TRISC = 0b00010000;
	ADCON1 = 0X00;
 //   nrf24_ce_pin_digitalwrite(LOW);
 //   nrf24_csn_digitalwrite(HIGH);
}


void nrf24_send(uint8_t* value)   // check with mirf
{
    /* Go to Standby-I first */
   // nrf24_ce_pin_digitalwrite(LOW);

    /* Set to transmitter mode , Power up if needed */
    nrf24_powerUpTx();
	nrf24_csn_digitalwrite(LOW);
	SPI_transfer(FLUSH_TX);
	nrf24_csn_digitalwrite(HIGH);
   

    /* Pull down chip select */
    nrf24_csn_digitalwrite(LOW);

    /* Write cmd to write payload */
    SPI_transfer(W_TX_PAYLOAD);

    /* Write payload */
    nrf24_transmitSync(value,1);

    /* Pull up chip select */
    nrf24_csn_digitalwrite(HIGH);

    /* Start the transmission */
    nrf24_ce_pin_digitalwrite(HIGH);
}



/*
void sendarray (uint8_t arg[], uint8_t length) {
  for (uint8_t n=0; n<length; ++n)
    nrf24_send(arg[n]);
}

*/




void main()
{
TRISB = 0b00000000;
TRISA = 0b00000000;
TRISC = 0b00010000;
SPI_init();
uint8_t data_array = 111;
//int *array_ptr = &data_array[0];
nrf24_configRegister(EN_AA,(0<<ENAA_P0)|(0<<ENAA_P1));
nrf24_init();
nrf24_powerUpTx();
__delay_ms(5);
//LED_PIN = HIGH;




while(1)
{

nrf24_send(&data_array);
__delay_us(20);
nrf24_ce_pin_digitalwrite(LOW);
  
    
      //  Read wl_module status 
      //  nrf24_csn_digitalwrite(LOW);                          // Pull down chip select
   //     status = SPI_transfer(NOP1);					// Read status register
     //   nrf24_csn_digitalwrite(HIGH);                              // Pull up chip select
		
	/*	
		if (status & (1<<TX_DS))							// IRQ: Package has been sent
		{
			
			//nrf24_configRegister(STATUS, (1<<TX_DS));	//Clear Interrupt Bit
			//PTX=0;
		}


	


*/

        uint8_t status;  
        nrf24_csn_digitalwrite(LOW);                          // Pull down chip select
        status = SPI_transfer(0xff);					// Read status register
        nrf24_csn_digitalwrite(HIGH);                              // Pull up chip select

if (status & (1<<TX_DS))							// IRQ: Package has been sent
		{
		LED_PIN = HIGH;
	nrf24_configRegister(STATUS, (1<<TX_DS));	//Clear Interrupt Bit if this line enabled led will not turn on as it clears TX_DS permanently. // if enable led should see blinking too fast
nrf24_csn_digitalwrite(LOW);                               // Pull down chip select
SPI_transfer(FLUSH_TX);						// Flush TX-FIFO
nrf24_csn_digitalwrite(HIGH); 
		}
else
{
LED_PIN = LOW;
}

	if (status & (1<<MAX_RT))							// IRQ: Package has not been sent, send again
		{
		
			nrf24_configRegister(STATUS, (1<<MAX_RT));	// Clear Interrupt Bit
			nrf24_ce_pin_digitalwrite(HIGH);								// Start transmission							
			nrf24_ce_pin_digitalwrite(LOW);
		}
 
  
		if (status & (1<<TX_FULL))							//TX_FIFO Full <-- this is not an IRQ
		{
			__delay_us(50); // resend package
            nrf24_ce_pin_digitalwrite(HIGH);  			// Pull up chip select
		
		}








__delay_ms(20); // wait some time

nrf24_ce_pin_digitalwrite(LOW);

}


}

 

[paulfjujo]

hello


what is the value of C1..?

if electrochemical type, maybe the leakage current can cause problem..
try with C1 100nF mylar type

[COLOR=#333333]#pragma config PWRTE = OFF [/COLOR]

you can also try to put ON PWRTE
it's allow some time to start the oscillator when power ON occurs.

 

[PA3040]

Method you are using configuration may be wrong

 

[asking]

Then what is the solution for my problem ? i did not understand what you mean to say ?

- - - Updated - - -

Ok my problem solved. R1 = 1K and R2 = 10K and C = 100n (104 Capacitor Code) Thanks for your support guyz

 

[PA3040]

Sorry your program is working for me

 

[wp100]

Then what is the solution for my problem ? i did not understand what you mean to say ?

- - - Updated - - -

Ok my problem solved. R1 = 1K and R2 = 10K and C = 100n (104 Capacitor Code) Thanks for your support guyz

Hi,

First off you resistor values are the wrong way round for that circuit R1 is 10k R2 is 1k.
Second there is no need for R2 as this is only needed where Mlclre pin has the option to be used as an input as well; the 877a does not.

Third, and I only have a pk2, so someone correct me if I am wrong, but the Pk3 user guide clearly states that you must not use a capacitor on Mclre, when in programming or debug mode.
All thats needed is a simple 10k pull up to Enable the Mlcre pin when in Run mode.

As Pauljugo said earlier make your PWRTE=ON, and also turn BOREN=OFF as Boren can cause more problems than its worth.

 

[andre_luis]

Ok my problem solved. R1 = 1K and R2 = 10K and C = 100n

Although you stated that problem is currently solved, I would suggest on further designs you consider improve circuit, just placing an anti-parallel diode for ensure instantaneous discharge of capacitor after power down, as shown bellow:

+++

 

[asking]

Great one will keep into consideration....