nrf2401 with PIC 18LF242

[xmtmega]

Hi guys,

Can you please help me with a few problems below:

1. I am using mplab to program the microcontroller 18LF242 with a 3V button battery. Is it alright as I found out that sometimes the PIC doesnt run and the Vdd is actually between 2.6 - 2.9V ?

2. I dont receive any signals from the transmitter… ? I am not sure if is because of the programming codes? Below are the receiver and transmitter codes:

#include <p18f242.h>

#include <delays.h>

#define DATA PORTCbits.RC2

#define CLK1 PORTCbits.RC1

#define CS PORTBbits.RB1

#define CE PORTBbits.RB5

#define act_addr 0b10101010 //Addr

#define data_w 16

#define addr_w 8

#define crc 0b01 // CRC enable

#define mode 0b01001111 // Rx2En = 0, Shockburst Mode, 250kbps,16 MHz module crystal, 0db Power

#define rf_ch 0x00 // 2400 MHz frequency channel

#pragma config OSC = HS

#pragma config WDT = OFF

#pragma config LVP = OFF

void main()

{

TRISCbits.TRISC3 = 0; // ON PWR_UP

PORTCbits.RC3 = 1;

Init_RF();

while(1){

initInterrupt();

Rx_En();

}

}

void Init_RF (void)

{

char addr_w_crc = ( addr_w << 2 )| crc;

char config[15] = {0,data_w, 0, 0, 0, 0, 0, 0, 0, 0, 0, act_addr, addr_w_crc, mode, 1};

int i, j;

TRISCbits.TRISC2 = 0;

TRISCbits.TRISC1 = 0;

TRISBbits.TRISB1 = 0;

TRISBbits.TRISB5 = 0;

Delay10KTCYx(2); // 5 msec (tpd2sby)

CE = 0; // Set configuration mode

CS = 1; // Select configuration register

Delay10TCYx(4); // 10 usec (tcs2data)

for ( i = 0; i < 15; i++)

{

for ( j = 7; j >= 0; j–) // send the configuration

{

DATA = config >> j;

• CLK(); // Clock in the data*

• }*

• }*

• CS = 0;*
  }
  void Rx_En(void)
  {

• int i;*

• char Rx_2400MHz = (rf_ch << 1) | 1; // configuration word*

• TRISCbits.TRISC2 = 0; // Set Outputs*

• TRISCbits.TRISC1 = 0;*

• TRISBbits.TRISB1 = 0;*

• TRISBbits.TRISB5 = 0;*

• CE = 0; // Set configuration mode*

• CS = 1; // Select configuration register*

• Delay10TCYx(4); // 10 usec (tcs2data)*

• for ( i = 7; i >= 0; i–)*

• {*

• DATA = Rx_2400MHz >> i; // Shift out Rx address*

• CLK(); // Clock in the data*

• }*

• CS = 0; // shift the configuration word*

• TRISCbits.TRISC2 = 1; // Set Data as Input*

• Delay100TCYx(10); // 250 usec (tsettling)*

• initInterrupt(); // Allow DR1 to interrupt MCU*
  CE = 1; // Turn on ACTIVE RX Mode

• Delay10TCYx(4); // 10 usec (tce2data)*
  }
  void Receive (void)
  {

• int i;*

• payload = 0;*

• //CE = 0;*

• for ( i = 15; i >= 0; i–)*

• {*

• CLK1 = 1; // Clock in the data*

• Delay10TCYx(10); // 500 nsec (tsetup)*

• Delay10TCYx(10); // 500 nsec (tsetup)*

• payload |= DATA << i; // Shift in payload*

• CLK1 = 0;*

• Delay10TCYx(10); // 500 nsec (tsetup)*

• Delay10TCYx(10); // 500 nsec (tsetup)*

• }*
  }
  //Initialisation of Interrupt subroutines
  void initInterrupt (void) {

• INTCONbits.INT0IE = 1; //enable INT1*

• RCONbits.IPEN = 1; //enable priority interrupts*

• INTCONbits.GIEH = 1; //enable all high priority interrupts*
  }
  void HI_isr_handler (void);
  #pragma code high_vector_section = 0x08
  void high_vector (void){

• _asm*

• GOTO HI_isr_handler*

• _endasm*
  }
  #pragma code
  #pragma interrupt HI_isr_handler
  void HI_isr_handler (void){

• if (INTCONbits.INT0IF ==1) {*
  Receive();

• INTCONbits.INT0IF = 0;*
  }
  }
  void Off_interrupt (void){

• INTCONbits.INT0IE = 0; //enable INT1*

• RCONbits.IPEN = 0; //enable priority interrupts*

• INTCONbits.GIEH = 0; //enable all high priority interrupts return;*

• INTCONbits.INT0IF = 0;*
  }
  void CLK(void)
  {

• Delay1TCY(); // 500 nsec (tsetup)*

• Delay1TCY(); // 500 nsec (tsetup)*

• CLK1 = 1; // clock in the value*

• Delay1TCY(); // 500 nsec (tsetup)*

• Delay1TCY(); // 500 nsec (tsetup)*

• CLK1 = 0;*
  }
  ///////////Transmiter part//////////////////////
  void main()
  {
  Init_RF();
  while(1){
  TRISCbits.TRISC3 = 0; // ON PWR_UP
  PORTCbits.RC3 = 1;
  Delay1KTCYx(12);
  Transmit(170);
  Delay10KTCYx(100); // 250 msec
  }
  } // End void main()
  void Transmit (int tx_payload)
  {

• int i;*

• Tx_En();*

• for ( i = 7; i >= 0; i–)*

• {*

• DATA = act_addr >> i; // Shift out Rx address*

• CLK(); // Clock in the data*

• }*

• for ( i = 15; i >= 0; i–)*

• {*

• DATA = tx_payload >> i; // Shift out payload CLK(); // Clock in the data*

• }*

• CE = 0;*
  }
  void Tx_En(void)
  {

• int i;*

• char Tx_2400MHz = (rf_ch << 1);*

• TRISCbits.TRISC2 = 0; //Set as outputs*

• TRISCbits.TRISC1 = 0;*

• TRISBbits.TRISB1 = 0;*

• TRISBbits.TRISB5 = 0;*

• CE = 0;*

• CS = 1;*

• Delay10TCYx(4); // 10 usec (tcs2data)*

• for ( i = 7; i >= 0; i–)*

• {*

• DATA = Tx_2400MHz >> i; // Shift out Rx address*

• CLK(); // Clock in the data*

• }*

• CS = 0; // shift the configuration word*

• Off_interrupt();// Disallow RD1 to interrupt MCU*

• Delay100TCYx(10); // 250 usec (tsettling)*

• CE = 1;*

• Delay10TCYx(4); // 10 usec (tce2data)*
  }

[jasonharper]

At 2.6V, a 18LF242 is only rated to run at a maximum of 13.8 MHz (see figure 22-2 in the datasheet). Based on comments in your code, you seem to be trying to run it at 16 MHz. If that 2.6V was measured with a multimeter, then I imagine that the lowest voltage seen by the PIC (at moments of maximum current consumption) is actually somewhat lower than that, making your hardware even further out of spec.

[xmtmega]

Thanks ! It works fine now, it was such a careless mistake.

But, I still having trouble to get any signal from the receiver… Since I disable the CRC, there is no random data which is expected to be there.

Is that because of any mistakes from the code ?

Appreciate for your help.

[brennen]

If you try to send a data packet do you get the TX_DS interrupt on the transmitter? If not, you’re not going to be receiving anything at the receiver. Check out my site (listed in my signature below), as I have working code for the 18F252, and you could easily use it as a framework to get your chip running by changing a few of the #defines (the code was created for Microchip’s C18 compiler). Otherwise you could just peruse the files to see how it’s done and find what’s going on in your code.