In order to make sure data could be transmitted in a standard and stable way between the application and the arduino, and vice-versa, a protocol was developed. The protocol was built on top of UART (Universal Asynchronous Receiver/Transmitter) interface, and it is based on a Request/Response message system (much like HTTP). It is a stateless server-client protocol, which means the server makes a request to the arduino and the later returns with a response.
Each message send over the protocol has a consistent and predefined format. A message consists of a text string, delimited by a newline character (i.e. "\n"). Every message must have a CODE (used to specify which action should be performed) and an optional DATA field (which will sometimes be needed to pass data onto the arduino).
The message format is described below.
#<CODE>$<DATA>
Below is a diagram describing how the protocol works.
| Code | Description | Data | Example Usage |
|---|---|---|---|
| P02 | Checks whether the given pin code is correct. | int - Pin Code | #P02$3333 |
| P03 | Gets current temperature. | N/A | #P03 |
| P04 | Gets current humidity percentage. | N/A | #P04 |
| P05 | Gets current lights state. | N/A | #P05 |
| P06 | Sets current lights state. | 0 - Lights ON; 1 - Lights OFF | #P06$0 |
| P07 | Activates security alarm. | N/A | #P07 |
| P08 | Gets current door button state. | N/A | #P09 |
| P09 | Gets current environment brightness percentage. | N/A | #P10 |
| P10 | Gets current flames status. | N/A | #P11 |
| P11 | Gets current lights control mode. | N/A | #P11 |
| P12 | Sets current lights control mode. | 0 - App; 1 - Remote | #P12$1 |
| P13 | Sets current lights color. | R - Red; G - Green; B - Blue; W - White | #P13$B |
| P14 | Activates fire alarm. | N/A | #P14 |
| P15 | Gets current brightness mode. | 0 - OFF; 1 - Auto | #P15$1 |
| P16 | Sets current brightness mode. | N/A | #P16 |
| P17 | Gets current brightness level. | N/A | #P17 |
| P18 | Sets current brightness level. | int - Brightness Level (20 - 80) | #P18$60 |
| P19 | Gets current fire alarm status. | N/A | #P19 |
| P20 | Sets current fire alarm status. | 0 - OFF; 1 - Auto | #P20$0 |
| P21 | Gets current brightness control mode. | N/A | #P21$0 |
| P22 | Sets current brightness control mode. | 0 - App; 1 - Potentiometer | #P22$0 |
| Code | Description | Data | Example Usage |
|---|---|---|---|
| D02 | Returns whether the given pin code is correct. | 0 - Incorrect; 1 - Correct | #D02$1 |
| D03 | Returns current temperature in Celsius. | float - Temperature | #D03$25.00 |
| D04 | Returns current humidity percentage. | float - Humidity | #D04$31.00 |
| D05 | Returns lights state. | ON - Lights ON; OFF - Lights OFF | #D05$OFF |
| D06 | Returns whether P06 was successful. | 0 - Failure; 1 - Success | #D06$0 |
| D07 | Returns whether P07 was successful. | 0 - Failure; 1 - Success | #D07$1 |
| D08 | Returns current door button state. | 0 - LOW; 1 - HIGH | #D09$1 |
| D09 | Returns current environment brightness percentage. | int - Brightness | #D10$23 |
| D10 | Returns current flames status. | 0 - Not detected; 1 - Flames detected | #D11$0 |
| D11 | Returns current lights control mode. | 0 - App; 1 - Remote | #D11$0 |
| D12 | Returns whether P12 was successful. | 0 - Failure; 1 - Success | #D12$1 |
| D13 | Returns whether P13 was successful. | 0 - Failure; 1 - Success | #D13$0 |
| D14 | Returns whether P14 was successful. | 0 - Failure; 1 - Success | #D14$0 |
| D15 | Returns whether P15 was successful. | 0 - Failure; 1 - Success | #D15$0 |
| D16 | Returns current brightness mode. | 0 - OFF; 1 - Auto | #D16$1 |
| D17 | Returns current brightness level. | int - Brightness Level | #D17$30 |
| D18 | Returns whether P18 was successful. | 0 - Failure; 1 - Success | #D18$1 |
| D19 | Returns current fire alarm status. | 0 - OFF; 1 - Auto | #D19$1 |
| D20 | Returns whether P20 was successful. | 0 - Failure; 1 - Success | #D20$0 |
| D21 | Returns current brightness control mode. | 0 - App; 1 - Potentiometer | #D21$1 |
| D22 | Returns whether P22 was successful. | 0 - Failure; 1 - Success | #D22$1 |
| Command | Description | Format |
|---|---|---|
| exit/quit | Exits program. | N/A |
| help | Help menu. List of available commands. | N/A |
| info | General info. | N/A |
| GET lights | Returns current lights state. | N/A |
| GET temperature | Returns current temperature. | N/A |
| GET humidity | Returns current humidity percentage. | N/A |
| GET brightness | Returns current brightness percentage. | N/A |
| GET flames | Returns whether flames are currently being detected. | N/A |
| GET firealarmstatus | Returns current fire alarm status. | N/A |
| GET lightcontrol | Returns current light control mode. | N/A |
| GET brightnessmode | Returns current brightness mode. | N/A |
| GET brightnesslevel | Returns current brightness mode. | N/A |
| GET brightnesscontrol | Returns current brightness control mode. | N/A |
| SET lights | Turns lights ON/OFF. | set lights <on/off> |
| SET lights | Sets lights color. | set lights <color> |
| SET lightcontrol | Sets lights control mode. | set lightcontrol <app/remote> |
| SET brightnessmode | Sets brightness mode. | set brightnessmode <off/auto> |
| SET brightnesslevel | Sets brightness level. | set brightnesslevel <20-80> |
| SET brightnesscontrol | Sets brightness control mode. | set brightnesscontrol <app/potentiometer> |
| SET firealarmstatus | Sets fire alarm status. | set firealarmstatus <off/auto> |
| TRIGGER securityalarm | Triggers security alarm. | N/A |
| TRIGGER firealarm | Triggers fire alarm. | N/A |