main.cpp

00001 #include "mbed.h"
00002 #include "nrf24l01.h"
00003 
00004 Serial pc(USBTX, USBRX); // tx, rx
00005 
00006 DigitalOut led1(LED1);
00007 DigitalOut led2(LED2);
00008 DigitalOut led3(LED3);
00009 DigitalOut led4(LED4);
00010 DigitalIn     mode(p20);
00011 
00012 DigitalOut     nRF_CSN(p8);
00013 DigitalOut     nRF_CE(p11);
00014 DigitalIn     nRF_IRQ(p12);
00015 SPI                    nRF_spi(p5, p6, p7);
00016 
00017 int main() {
00018     uint8_t dump[35];
00019     unsigned char scratch[5];
00020     pc.baud(115200);
00021     pc.printf("mbed: nRF24L01 tranceiver\r\n");
00022 
00023     #define _NRF24L01P_SPI_MAX_DATA_RATE     10000000
00024     nRF_spi.frequency(_NRF24L01P_SPI_MAX_DATA_RATE/5);     // 2Mbit, 1/5th the maximum transfer rate for the SPI bus
00025   nRF_spi.format(8,0);                                   // 8-bit, ClockPhase = 0, ClockPolarity = 0
00026 
00027     //scratch[0] = 0x01;
00028     //nrf24l01_write_register(nrf24l01_RF_SETUP, scratch , 1);    // -18 dbm, air rate 1 mbps
00029     
00030     pc.printf("Reading all registers:\r\n");
00031     nrf24l01_get_all_registers(dump);
00032     for(int i=0; i<sizeof(dump); i++){
00033         pc.printf("0x%02x\r\n",dump[i]);
00034     }
00035     
00036     /* "fork" */
00037     if(mode){
00038         // TX Mode
00039         pc.printf("Set to transmitter mode p20 high\r\n");
00040         //vars
00041         unsigned char data; //register to hold letter sent and received
00042         unsigned int count; //counter for for loop
00043         // init
00044         nrf24l01_initialize_debug(false, 1, true); //initialize the 24L01 to the debug configuration as TX, 1 data byte, and auto-ack enabled
00045         //main program loop
00046         while(1)
00047         {
00048             //check UART status register to see if data has been received.  if so, process
00049             while(pc.readable())
00050             {
00051                 data = pc.getc(); //get data from UART
00052                 nrf24l01_write_tx_payload(&data, 1, true); //transmit received char over RF
00053 
00054                 //wait until the packet has been sent or the maximum number of retries has been active
00055                 while(!(nrf24l01_irq_pin_active() && (nrf24l01_irq_tx_ds_active() || nrf24l01_irq_max_rt_active())));
00056 
00057                 //check to see if the maximum number of retries has been hit.  if not, wait for the RX device
00058                 // to send the char back.  if so, assume the packet is lost and send "*" back to UART
00059                 if(!nrf24l01_irq_max_rt_active())
00060                 {
00061                     nrf24l01_irq_clear_all(); //clear all interrupts in the 24L01
00062                     nrf24l01_set_as_rx(true); //change the device to an RX to get the character back from the other 24L01
00063 
00064                     //wait a while to see if we get the data back (change the loop maximum and the lower if
00065                     //  argument (should be loop maximum - 1) to lengthen or shorten this time frame
00066                     for(count = 0; count < 25000; count++)
00067                     {
00068                         //check to see if the data has been received.  if so, get the data and exit the loop.
00069                         //  if the loop is at its last count, assume the packet has been lost and set the data
00070                         //  to go to the UART to "?".  If neither of these is true, keep looping.
00071                         if((nrf24l01_irq_pin_active() && nrf24l01_irq_rx_dr_active()))
00072                         {
00073                             nrf24l01_read_rx_payload(&data, 1); //get the payload into data
00074                             break;
00075                         }
00076                         
00077                         //if loop is on its last iteration, assume packet has been lost.
00078                         if(count == 24999)
00079                             data = '?';
00080                     }
00081                     
00082                     nrf24l01_irq_clear_all(); //clear interrupts again
00083                     pc.printf("%c", data); //print the received data (or ? if none) to the screen
00084                 
00085                     wait_us(130); //wait for receiver to come from standby to RX
00086                     nrf24l01_set_as_tx(); //resume normal operation as a TX
00087                 }
00088                 else
00089                 {
00090                     nrf24l01_flush_tx(); //get the unsent character out of the TX FIFO
00091                     nrf24l01_irq_clear_all(); //clear all interrupts
00092                     pc.printf("*"); //print "*" to the screen to show that the receiver did not receive the packet
00093                 }
00094                                         
00095                 led1 = !led1; //toggle the on-board LED as visual indication that the loop has completed
00096             }
00097         }
00098 /* ########################################################################## */        
00099     }else{
00100         // RX Mode
00101         pc.printf("Set to receiver mode p20 low\r\n");
00102         unsigned char data; //register to hold letter received and sent
00103         // Init
00104         nrf24l01_initialize_debug(true, 1, true); //initialize the 24L01 to the debug configuration as RX, 1 data byte, and auto-ack enabled        
00105         //main program loop
00106         while(1)
00107         {
00108             //wait until a packet has been received
00109             while(!(nrf24l01_irq_pin_active() && nrf24l01_irq_rx_dr_active()));
00110             
00111             nrf24l01_read_rx_payload(&data, 1); //read the packet into data
00112             nrf24l01_irq_clear_all(); //clear all interrupts in the 24L01
00113             
00114             pc.putc(data);
00115             wait_us(130); //wait for the other 24L01 to come from standby to RX
00116             
00117             nrf24l01_set_as_tx(); //change the device to a TX to send back from the other 24L01
00118             nrf24l01_write_tx_payload(&data, 1, true); //transmit received char over RF
00119             
00120             //wait until the packet has been sent or the maximum number of retries has been reached
00121             while(!(nrf24l01_irq_pin_active() && (nrf24l01_irq_tx_ds_active() || nrf24l01_irq_max_rt_active())));
00122 
00123             nrf24l01_irq_clear_all(); //clear interrupts again
00124             nrf24l01_set_as_rx(true); //resume normal operation as an RX
00125 
00126             led1 = !led1; //toggle the on-board LED as visual indication that the loop has completed
00127         }
00128     }
00129 }