RoboDoor - A room access control project

Table of contents

1. What is this project?
2. Functionality of the controller
3. Supported devices
4. Functions in this project

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1. What is this project?

RoboDoor is a room access control system which I built to limit the entries to my lab to only those who have "Authorised" cards. It utilizes ID-20 RFID reader module (I got mine from sparkfun), and the compares the RFID tag to a list of tags inside it. Buzzer and LED gives an AudioVisual feedback, and a solenoid (also from Sparkfun) opens the door latch.

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2. Functionality of the controller

The microcontroller does a very simple task, according to the datasheet of the ID-20 RFID reader, the data output format is as follows

Output Data Structure – ASCII STX (02h) DATA (10 ASCII) CHECK SUM (2 ASCII) CR LF ETX (03h) [The 1byte (2 ASCII characters) Check sum is the “Exclusive OR” of the 5 hex bytes (10 ASCII) Data characters.]

I decided to make it very simply and not even do a CHECKSUM, just use the byte as part of the tag, I ignore the STX and the CR LF ETX parts and compared the 12 ASCII characters, if match, open the door, if no BEEB BEEB BEEB

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3. Supported devices

Though I have only tested this code on an ATmega328P it should be running on all major ATmega AVRs like:

• ATmega644
• ATmega32
• ATmega16
• ATmega328/P
• ATmega168/P
• ATmega88/P
• ATmega44/P
• ATmega8

If your device is not supported you can probably adapt this code easily to your needs by having a look at the your device's datasheet and changing the register names appropriately

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4. Functions in this project

• ISR(USART_RX_vect)
• void init_sys(void)
• uint8_t MatchTagID(char * Tag1, char * Tag2)
• uint8_t MatchToTable (char * Tag)
• void AcceptTag(void)
• void RejectTag(void)

ISR(USART_RX_vect)

Receives the USART characters and adds them to a buffer

void init_sys(void)

Initilization function

uint8_t MatchTagID(char * Tag1, char * Tag2)

Compares to strings, the first is the received tag and the other is a tag from a table

uint8_t MatchToTable (char * Tag)

Sends the received tag as well as a tag from a table to the MatchTagID function to compare them

void AcceptTag(void)

As it says :) it turns on an LED and opens the door

void RejectTag(void)

as it says, ;) BEEB BEEB BEEB