I am trying to get wireless communication implemented on a robotics project I am working on. I'm using a PIC18F4550, PIC18F2550, and two Nordic nRF24L01's. I'm having trouble on the transmission side; for some reason the IRQ pin does not toggle to indicate that a packet has been successfully sent.
I've included the code below, any help is much appreciated.
/*
Wireless communication using a PIC18F4550 (master) and nRF24L01 (slave) - Transmitter
*/
/*****************************************************
Includes
**************************************************** */
// Include files
#include <p18cxxx.h> // Finds correct header for any PIC18
#include <delays.h> // Enables you to add varying amount of NOPs (Delays)
#include <stdlib.h>
#include <spi.h> // Just in case we want to cheat with SPI
// Define names for LED pins
//#define LED1 PORTAbits.RA0 // blinky light (code is running)
#define LED1 LATAbits.LATA0 // blinky light (code is running)
// Define names for SPI connection pins
//#define CE PORTAbits.RA2 // Chip Enable (CE) -- Pin that activates RX or TX mode
#define CE LATAbits.LATA2 // Chip Enable (CE) -- Pin that activates RX or TX mode
#define IRQ PORTBbits.RB2 // Interrupt Request (IRQ) -- Pin that signals transmission
#define SDO TRISCbits.TRISC7 // Serial Data Out (SDO) -- Pin that data goes out from
#define SDI TRISBbits.TRISB0 // Serial Data In (SDI) -- Pin that data comes in to
#define SCK TRISBbits.TRISB1 // Serial Clock (SCK) -- Pin that sends clock signal to sync all SPI devices
// Define names for "Slave Select" pins
//#define SS PORTAbits.RA4 // Slave Select (SS) -- Pin that selects "slave" module to communicate with
#define SS LATAbits.LATA4 // Slave Select (SS) -- Pin that selects "slave" module to communicate with
#define select 0 // Device is "active low," define "select" as 0
#define deselect 1
// Define names for SPI configuration pins
#define SMP SSPSTATbits.SMP // Sample Bit (SMP) -- Pin that sets where to sample data
#define CKP SSPCON1bits.CKP // Clock Polarity (CKP) -- Pin that sets where SCK will idle
#define CKE SSPSTATbits.CKE // Clock Edge Select (CKE) -- Pin that sets which transition transmission takes place
#define SSPEN SSPCON1bits.SSPEN // Serial Prt Enbl (SSPEN) -- Pin that will enable serial port and configure SCK, SDO, SDI and SS as serial port pins
#define WCOL SSPCON1bits.WCOL // Write Collision (WCOL) -- Detect bit
//#define WCOL_LED PORTCbits.RC1 // Write Collision (WCOL) -- Pin for collision visual
#define WCOL_LED LATCbits.LATC1 // Write Collision (WCOL) -- Pin for collision visual
// Define commands for Nordic via SPI
#define R_REGISTER 0x00
#define W_REGISTER 0x20
#define R_RX_PAYLOAD 0x61
#define W_TX_PAYLOAD 0xA0
#define FLUSH_TX 0xE1
#define FLUSH_RX 0xE2
#define REUSE_TX_PL 0xE3
#define NOP 0xFF
// Define Nordic registers
#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
/*****************************************************
Function Prototypes & Variables
**************************************************** */
void initChip(void);
void init_spi_master(void);
void init_nordic(void);
void InterruptHandler_SPI(void);
void InterruptHandler_Nordic(void);
void delay(void);
void spi_write(int data);
void transmit_data(int data);
unsigned char spi_transmission_done;
unsigned char data_sent;
unsigned char data;
unsigned char dummy;
/*************************************************
RESET VECTORS: REMOVE IF NOT USING BOOTLOADER!!!
**************************************************/
extern void _startup (void);
#pragma code _RESET_INTERRUPT_VECTOR = 0x000800
void _reset (void)
{
_asm goto _startup _endasm
}
#pragma code
/*************************************************
Interrupt Service Routines
**************************************************/
#pragma code _HIGH_INTERRUPT_VECTOR = 0x000808
void _high_ISR (void)
{
InterruptHandler_SPI();
InterruptHandler_Nordic();
}
#pragma code
#pragma code _LOW_INTERRUPT_VECTOR = 0x000818
void _low_ISR (void)
{
InterruptHandler_Nordic();
}
#pragma code
void delay() {
int counter = 0;
for (counter = 0; counter<30000; counter++) {
;
}
}
/*********************************************************
Interrupt Handlers
**********************************************************/
#pragma interrupt InterruptHandler_SPI
void InterruptHandler_SPI(void) {
if(PIR1bits.SSPIF == 1) // SPI Interrupt
{
PIR1bits.SSPIF = 0; // clear interrupt
spi_transmission_done = 1;
}
}
#pragma interrupt InterruptHandler_Nordic
void InterruptHandler_Nordic(void) {
if(INTCON3bits.INT2IF == 1) // Nordic Interrupt
{
INTCON3bits.INT2IF = 0; // clear interrupt
// spi_write(W_REGISTER+STATUS); // Write to the STATUS register
// spi_write(0b01111110); // Reset
// spi_write(FLUSH_TX); // Flush the FIFO
data_sent = 1;
}
}
/*************************************************
Initialize the PIC
**************************************************/
void initChip(){
PORTA = 0x00; // reset all PORT registers
PORTB = 0x00;
PORTC = 0x00;
PORTD = 0x00;
PORTE = 0x00;
TRISA = 0x00; // set all PORTA to be OUTPUT
TRISB = 0b00000101; // set RB0 and RB2 as INPUT
// and the rest of PORTB as OUTPUT
TRISC = 0x00; // set all PORTC to be OUTPUT
TRISD = 0x00; // set all PORTD to be OUTPUT
TRISE = 0x00; // set up PORTE to be OUTPUT
ADCON1 = 0b00001111; // set up PORTA to be digital I/Os
spi_transmission_done = 0; // initilize variables
data_sent = 0;
dummy = 0b00000000;
data = 0b11111111;
}
/*************************************************
Initialize the SPI Master
**************************************************/
void init_spi_master() {
SDI = 1; // Serial Data In - enable master mode
SCK = 0; // Serial Clock - clear TRISB1 for master
SDO = 0; // Serial Data Out - clear TRISC7
SS = deselect;
SMP = 0; // Sample bit - sample in middle
CKP = 0; // Clock Polarity - low when idle **MUST BE SAME ON MASTER AND SLAVE**
CKE = 0; // Clock Edge Select - transmit on transition from idle clock state to active
SSPCON1bits.SSPM3 = 0; // Set the clock rate in master mode
SSPCON1bits.SSPM2 = 0; // to be FOSC/16 (Frequency of Oscillation)
SSPCON1bits.SSPM1 = 0;
SSPCON1bits.SSPM0 = 1;
SSPEN = 0; // Wait to enable serial port and configure SCK, SDO, SDI and SS as serial port pins
PIE1bits.SSPIE = 1; // enable SPI interrupt
}
/*************************************************
Initialize the Nordic
**************************************************/
void init_nordic() {
RCONbits.IPEN = 1; // enable priorities levels on interrupts
INTCON3bits.INT2IE = 1; // enable the INT2 (IRQ) external interrupt
INTCON3bits.INT2IP = 1; // IRQ is high priority
INTCON2bits.INTEDG2 = 0; // IRQ is triggered on falling edge
spi_write(W_REGISTER+CONFIG); // Write to the CONFIG register
spi_write(0b01001110); // [7] Reserved
// [6] RX_DR Interrupt 1 - mask
// [5] TX_DS Interrupt 0 - unmask
// [4] MAX_RT Interrupt
// [3] Enable CRC
// [2] 2 byte CRC
// [1] PWR_UP
// [0] TX
spi_write(W_REGISTER+SETUP_AW); // Write to the SETUP_AW register
spi_write(0b00000011); // Set the width to 5 bytes
spi_write(FLUSH_TX); // Flush the FIFO
CE = 0; // hold CE low to transmit
}
/*************************************************
Functions for Writing Data
**************************************************/
void spi_write(int data) {
SSPEN = 1; // Enable serial port and configure SCK, SDO, SDI and SS as serial port pins
if(WCOL == 0) { // collision testing
SS = select;
SSPBUF = data;
SS = deselect;
}
else { // there is a collision
WCOL = 0;
WCOL_LED = !WCOL_LED; //visual to see a collision
}
delay(); // band-aid that fixes collisions during multiple writes
}
void transmit_data(int data) {
data_sent = 0;
spi_write(W_TX_PAYLOAD); // send command for transmission
spi_write(data); // load data
CE = 1; // toggle CE for >10ns to send packet
delay();
CE = 0;
}
/******************************************************************************/
/* Main Program */
/******************************************************************************/
void main() {
initChip();
init_spi_master();
init_nordic();
INTCONbits.GIEH = 1; // enables all high priority interrupts
INTCONbits.GIEL = 1; // enables all low priority interrupts
transmit_data(data); // send some data
while (1) {
LED1 = !LED1; // toggle LED - program is running
dummy = SSPBUF; // in case there is something in there, get rid of it
if(IRQ == 0){
PORTD = 0b11111111;
}
if(spi_transmission_done == 1){
dummy = SSPBUF;
spi_transmission_done = 0;
}
if(data_sent == 1){
PORTD = 0b11111111;
transmit_data(data); // send some more data
}
delay(); // LED blinks
data++;
}
}
