As a first project I set out to build a mobile RFID reader posting live data to either MySQL, Google Sheets or Ubidots via Webhooks.
- photo credit: Migal Vanas
Note:
This is not a tutorial as such, rather just a showcase of the product. As I have had much help from the Particle Forum, I have deiced to publish my Eagle files and code to make it available to anyone that might want to use it.
I assume you have basic knowledge of the Particle environment, web hooks and have set up your account and devices in Particle Console. If not, please do so before attempting this build.
The brief:
Building a truly wireless (mobile) RFID scanner with the purposed of scanning RFID cards, capturing the UIDâs off these cards and posting them to either;
- Google Sheets
- MySQL Database
- Dashboard
Bill of materials:
- MFRC522 card reader module
- 3.7V LiPo 1100mA Battery
- Battery Charing module
- LM394N
- Bunch of 0603 LEDs for battery indicator
- 2 x RGB LEDs for system status and card read status
- Particle Photon
- Slide switch - Main power
- Tilt switch
- Custom design PCB
- Custom design enclosure
- Various 0603 resistors
- Ferrite !!!
First things first:
If you are anything like me, simple generic prototype enclosure will not suffice, so I put a little extra effort in, got to know my way around Rhinoceros and designed a simple, yet elegant (or at least I thought so) enclosure that would showcase the Particle Photon and some other components.
In addition to this, I decided not to opt for a generic proto board as I absolutely HATE wires. I included an image of my initial attempt to make a âprettyâ board using proto board and jumper wires, but after couple of hours realised it simply wonât do. Yet another learning curve, Googleâd and spent couple of hours on YouTube and managed to find my way around Autodesk Eagle. Worth every minute spent.
***The last image indicating the fully assembled PCB with status LED indicating "OK" as well as the LM3914N in action indicating ±90% charged battery. (7 of 8 LEDâs)
Submitted the Gerber files to PCBWAY and in less than a week and In had my brand new custom PCBâs ready for assembly.
The important stuff:
Now the coding, this is the part that I struggle with the most, but thanks to some helpful gentleman on the Particle and Hackster forums, I came up with the code below. Now it probably is not the cleanest code ever written, but it works, so feel free to use and improve if youâd like.
// Project: Mobile RFID Attendence register
// A project by FireFli (PTY) LTD
// Date: July 2019
// Compiled by: Friedl Basson
// Details: Scan for UID's from RFID cards and posting via webhooks to, UbiDots, mySQL DB or Google Sheets
// Credits: Sepcial thanks to the Particle community for assisting and making this project possible!
// Firmware: V2.1.1
//System Mode// - comment out if you will be settng up WiFi via Particle app and do not need to connect to another Wireless network aftwer the fact
//SYSTEM_MODE(SEMI_AUTOMATIC);
// This #include statement was automatically added by the Particle IDE.
#include "RFID.h"
#include <Ubidots.h>
/* Define the pins used for the SS (SDA) and RST (reset) pins for BOTH hardware and software SPI */
#define SS_PIN A2
#define RST_PIN D2
/* Define the pins used for the DATA OUT (MOSI), DATA IN (MISO) and CLOCK (SCK) pins for SOFTWARE SPI ONLY */
#define MOSI_PIN D3
#define MISO_PIN D4
#define SCK_PIN D5
//Initialising RGB START - RGB LED and buzzer is used as system status indicator
int redPin = D6;
int greenPin = D1;
int bluePin = D0;
int buzzPin = D7;
//Initializing RGB END
/* Create an instance of the RFID library */
#if defined(_USE_SOFT_SPI_)
RFID RC522(SS_PIN, RST_PIN, MOSI_PIN, MISO_PIN, SCK_PIN); // Software SPI
#else
RFID RC522(SS_PIN, RST_PIN); // Hardware SPI
#endif
//const char* WEBHOOK_NAME = "rfid_uid";
const char* WEBHOOK_NAME = "Ubidots";
Ubidots ubidots("webhook", UBI_PARTICLE);
void setup()
{
Serial.begin(9600);
// WiFi.listen();
pinMode(redPin, OUTPUT);
pinMode(greenPin, OUTPUT);
pinMode(bluePin, OUTPUT);
pinMode(buzzPin, OUTPUT);
// Setting credentials for new WiFi Connection
/*
This section is only needed if you want to connect to a new WiFi Network after initial setup
This will only work if current WiFi credentials have been cleared.
Code will run ONLY ONCE on startup and set new crediatials specified. Once new credentials is set, this code will not run again.
*/
WiFi.on();
if (!WiFi.hasCredentials()) {
WiFi.setCredentials("SSID", "PASSWORD", WPA2, WLAN_CIPHER_AES);
}
WiFi.connect();
waitUntil(WiFi.ready);
Particle.connect();
#if !defined(_USE_SOFT_SPI_)
/* Enable the HW SPI interface */
SPI.setDataMode(SPI_MODE0);
SPI.setBitOrder(MSBFIRST);
SPI.setClockDivider(SPI_CLOCK_DIV8);
SPI.begin();
#endif
/* Initialise the RFID reader */
RC522.init();
delay(5000);
digitalWrite(bluePin, HIGH);
digitalWrite(greenPin, HIGH);
digitalWrite(redPin, LOW);
}
void loop()
{
/* Temporary loop counter */
uint8_t i;
/* Has a card been detected? */
if (RC522.isCard())
{
/* If so then get its serial number */
RC522.readCardSerial();
char str[16];
snprintf(str, sizeof(str)
, "%02X %02X %02X %02X"
, RC522.serNum[0]
, RC522.serNum[1]
, RC522.serNum[2]
, RC522.serNum[3]
);
// Webhooks//
/*
RFID_WP = your webhook name
str = your data you want to publish
PRIVATE or PUBLIC
*/
// Particle.publish("RFID_WP", str, PRIVATE); //Publish Data to Wordpress DB
// Particle.publish("XLS", str, PRIVATE); // Publish Data to Google Sheets
Serial.print(str);
/* Adds context key-value pairs */
ubidots.addContext("UID", str);
char* context = (char *) malloc(sizeof(char) * 60);
/* Builds the context with the array above to send to Ubidots */
ubidots.getContext(context);
ubidots.add("UID", 1, context); // Change for your variable name
bool bufferSent = false;
bufferSent = ubidots.send(WEBHOOK_NAME, PUBLIC); // Will use particle webhooks to send data
//}
// - TRY Ubidots - //
// digitalWrite(buzzPin, HIGH);
delay(500);
digitalWrite(buzzPin, LOW);
digitalWrite(bluePin, LOW);
delay(750);
digitalWrite(bluePin, HIGH);
}
else if (RC522.isCard())
{
RC522.readCardSerial();
char str[16];
snprintf(str, sizeof(str)
, "%02X %02X %02X %02X"
, RC522.serNum[0]
, RC522.serNum[1]
, RC522.serNum[2]
, RC522.serNum[3]
);
digitalWrite(bluePin, LOW);
digitalWrite(greenPin, LOW);
digitalWrite(redPin, HIGH);
// digitalWrite(buzzPin, HIGH);
delay(1000);
digitalWrite(bluePin, HIGH);
digitalWrite(greenPin, HIGH);
digitalWrite(redPin, LOW);
digitalWrite(buzzPin, LOW);
}
delay(500);
}
Front Ends:
Thanks the the webhook function in the Particle Console, I was able to seamlessly post code to just about anywhere. Now if you know PHP and MySQL quite well, you might be able to write your own server side script, but for those who are new to this like me, I would recommend the following two services;
- Zapier
- Ubidots
The differ vastly, so you have a look at both to determine which is more suitable for your use. Bottom line, if you want the data to be published live to a location of your choice, Zapier (or something similar) is the way to go. If you do not mind storing data on someone elseâs server, Ubidots is a much more cost effective (cost per datapoints) way to go and has the added benefit of some nifty widgets to present your data in a graphical way. I have attached a screen grab of a sample Dashboard I build in Ubidots.
- photo credit: Migal Vanas
In hind sight:
Initially I though building a battery indicator that works outside of the Microcontroller was the best idea as It would function independently and it frees up much needed digital pins, but the trade-off to this is that without an analogue input being sent to the MC, you are not able to display the battery life on a dashboard. The LM3914N also requires some calculations to set reference volutes and to determine which resistors to use depending on your voltage difference between âfully chargeâ and âdepletedâ status. Keep in mind that for all praticle reasons you should work with 3.1V on the battery as depleted as most components will not work below 3V or start behaving sporadically. Six of the one I suppose.
I would also not make use of the tilt switch again to trigger the battery indicator as it is to sensitive and causes âflickerâ. A simple tactile switch seems like a much better idea⊠just a though.
A Must:
The biggest learning curve here for me was the effect any metal or circuit will have and a RFID reader. I designed, built and tested the entire unit first connected to a constant PSU. Due to the compact design of the unit, the battery was installed in very close proximity to the RFID reader module. The consequenceâŠ. No scans 
As I temporary measure I wrapped the battery in electrical insulation tape which did an âokâ job. I ordered some Ferrite from Amazon as a Hail Mary and like magic the interference was a thing of the past.
Thank you to everyone that assisted with the project in some way, @ScruffR for understanding we all had to start somewhere and showing extreme patience 
Also a huge thank you to @Joe at Particle for the awesome Maker Kits. Looking forward to more projects!!!
Files:
Eagle Schematic - DOWNLOAD
Eagle Board File - DOWNLOAD
