Hello, all.
This is my first post. I have read numerous other forums to get this far in my project, however I have hit a major roadblock. Software is my profession and Im learning how hardware as I go 
The overall idea for my project is to have multiple Arduino Nano's (important note for below: right now I am using UNO's) wired with MRFC522 RFID reader module and NRF34L01 radio module. Each "slave" Arduino will send the RFID UID card value to the "master" Arduino (either be a nano or Uno, have not gotten that far yet) where some logic will be computed and output set.
Presently, my issue is with the slave program.
A basic MRFC522 sketch (not provided) has proven that I am able to get the module working on its own. And by working, I mean detected a new card, read the UID and output it to serial.
Following Simple nRF24L01+ 2.4GHz transceiver demo I was able to get a basic RF Tx/Rx working with relative reliability. Reliability increased with adding the capacitor and external power.
My trancieveing nRF24L01 is equipped with its own 2 AA battery power supply and has a 10 µF capacitor soldered to the source. The receiving end has a smaller capacitor 100 nF capacitor on it using the 3.3v pin of the Arduino Uno
The MRFC522 is connected to the 3.3V pin on the Arduino board.
Both the MRFC522 and nRF24L01 share the common SPI bus line (SCK, MOSI, MISO). Both have their own slave select pins (detailed in the Rx code below).
The Tx code is where I believe my issue is. The expected behavior of the below Tx code is to:
- Init components/modules in the setup() function
(In the loop() function): - Transmit an a message to the reciever (which will print out the message; in this case it will be "Message1")
2a. Then, check to see if a PICC card is present and the serial is able to be read (i.e. a card has been placed in front of the RFID reader).
2b. If true, transmit another message to listening receivers, this time "Message2"
2c. Else, do nothing, go to top of loop
The actual behavior right now is I am able to transmit the first message with some confidence.
( Hesitation is that there appears to be an irregular pattern to the message being received. In the test program where I was JUST Tx/Rx, the receive stream (i.e. printing to serial from the Rx program) was consistently providing output in relation to the delay() I had set. )
When a PICC card is present and the serial is able to be read, the second message is NOT sent and transmission stops until I remove the card (its as if it has become a blocking call?). Once the card has been removed, and that if-conditional is false, the first message ("Message1") begins transmitting in the irregular pattern again.
In summary, my question is 2-fold:
- How can I get the two interfaces to cooperate
- How can i get the two interfaces to cooperate in a reliable and predictable manner? (ultimately, this will be used in a system where reliability is paramount).
Transmitting Code (Tx)
RFID_basic.ino
#include <MFRC522.h>
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
#define RST_PIN 9 // Configurable, see typical pin layout above
#define SS_PIN 10 // Configurable, see typical pin layout above
#define CE_PIN 7
#define CSN_PIN 8
RF24 radio(CE_PIN, CSN_PIN);
const byte address[6]="00001";
MFRC522 rfid(SS_PIN, RST_PIN); // Create MFRC522 instance
String ACCEPTED = String("23327250110");
void setup() {
Serial.begin(9600);
pinMode(CE_PIN,OUTPUT);
pinMode(CSN_PIN,OUTPUT);
pinMode(RST_PIN,OUTPUT);
pinMode(SS_PIN,OUTPUT);
radioOFF();
rfidOFF();
SPI.begin();
// NRF
radioON();
radio.begin();
radio.setChannel(115);
radio.setPALevel(RF24_PA_MIN);
radio.setDataRate(RF24_250KBPS);
radio.openWritingPipe(address);
radioOFF();
// MRFC
rfidON();
rfid.PCD_Init();
rfid.PCD_DumpVersionToSerial();
rfidOFF();
Serial.println("READY TO SCAN");
}
void loop() {
radioON();
const char text[] = "Message1";
const char text2[] = "Message2";
radio.write(&text,sizeof(text));
radioOFF();
rfidON();
if( rfid.PICC_IsNewCardPresent() && rfid.PICC_ReadCardSerial() )
{
rfidOFF();
//Serial.println("CARD FOUND");
radioON();
radio.write(&text2,sizeof(text2));
radioOFF();
}
rfidOFF();
delay(500);
}
/*
Checks the ACCEPTED array to see if the value of scanned is something we are looking for
*/
int isAcceptedCard (String card)
{
return ACCEPTED.equals(card);
}
/*
/*
Returns the RFID card UID as a String
*/
void dump_byte_array(char *card, byte *buffer, byte bufferSize) {
//char s[64];
for (byte i = 0; i < bufferSize; i++) {
card[i] = buffer[i];
}
//return ;
}
/*
RADIO TOGGLES
*/
void radioOFF()
{
digitalWrite(CE_PIN,HIGH);
digitalWrite(CSN_PIN,HIGH);
}
void radioON()
{
digitalWrite(CE_PIN,LOW);
digitalWrite(CSN_PIN,LOW);
}
/*
RFID TOGGLES
*/
void rfidOFF()
{
digitalWrite(RST_PIN,HIGH);
digitalWrite(SS_PIN,HIGH);
}
void rfidON()
{
digitalWrite(RST_PIN,LOW);
digitalWrite(SS_PIN,LOW);
}
Receiving code:
simpleRx.ino
#include <SPI.h>
#include <nRF24L01.h>
#include "RF24.h"
#define CE_PIN 7
#define CSN_PIN 8
RF24 radio(CE_PIN,CSN_PIN);
const byte address[6]="00001";
void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
radio.begin();
radio.setChannel(115);
radio.setPALevel(RF24_PA_MIN);
radio.setDataRate(RF24_250KBPS);
radio.openReadingPipe(0,address);
radio.startListening();
Serial.println("READY TO RECIEVE");
}
void loop() {
while(radio.available()){
char text[32] = "";
radio.read(&text,sizeof(text));
Serial.println(text);
}
}
Images of my connections, can provide more photos or details if need be!
Thank you to any that made it this far. I really want to understand why this is not working. It seems to me this is a SPI issue. However, pulling the control pins to HIGH/LOW do not seem to be responsive.