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Overview

The Light Sensor (LDR) endpoint allows you to submit light intensity readings from Light Dependent Resistor (LDR) sensors monitoring plant environments. This endpoint tracks luminosity levels to ensure optimal lighting conditions.

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Endpoint

POST /api/ldr/

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Model Structure

The Ldr model extends the base Sensor model: 
class Ldr(Sensor):
    luminosidade = models.FloatField(max_length=200, default='00')
    media_luminosidade = models.FloatField(max_length=200, default='30')
    unidade_medida = models.CharField(max_length=50, default='lumen')
Source: models.py:38-43

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ViewSet Implementation

class LdrViewset(viewsets.ViewSet):
    permission_classes = (IsAuthenticated,)
    
    def create(self, request):
        serializer = LdrSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        the_response = LdrSerializer(serializer.save())
        return Response(the_response.data, status=status.HTTP_201_CREATED)
Source: views.py:133-139

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Authentication

This endpoint requires authentication. Include your API token in the Authorization header.
Authorization: Token 2d75140c068049278f9cb7d39b1a20f05aecdc56
See Authentication for details.

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Request Parameters

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nome
string
required
Sensor name identifierExample: "LDR"
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tipo
string
required
Type of sensor locationExample: "Plantas"
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grupo
string
required
Sensor group classificationExample: "Grupo P"
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luminosidade
float
required
Current light intensity reading from the sensorExample: 450.5
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media_luminosidade
float
required
Average or target light intensity levelDefault: 30Example: 30
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unidade_medida
string
required
Unit of measurement for light intensityDefault: "lumen"Example: "lumen"

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Response Fields

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id
integer
Auto-generated unique identifier for the record
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nome
string
Sensor name as provided in request
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tipo
string
Sensor type as provided in request
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grupo
string
Sensor group as provided in request
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luminosidade
float
Current light intensity value submitted
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media_luminosidade
float
Average or target light intensity level
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unidade_medida
string
Unit of measurement for light intensity
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data_criacao
datetime
Timestamp when the record was created (auto-generated)

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Example Request

curl -X POST http://127.0.0.1:8000/api/ldr/ \
  -H "Authorization: Token 2d75140c068049278f9cb7d39b1a20f05aecdc56" \
  -H "Content-Type: application/json" \
  -d '{
    "nome": "LDR",
    "tipo": "Plantas",
    "grupo": "Grupo P",
    "luminosidade": "450.5",
    "media_luminosidade": 30,
    "unidade_medida": "lumen"
  }'

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Example Response

Status Code: 201 Created 
{
  "id": 89,
  "nome": "LDR",
  "tipo": "Plantas",
  "grupo": "Grupo P",
  "luminosidade": 450.5,
  "media_luminosidade": 30.0,
  "unidade_medida": "lumen",
  "data_criacao": "2026-03-11T10:30:45.123456Z"
}

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Error Responses

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Missing Authentication Token

Status Code: 401 Unauthorized 
{
  "detail": "Authentication credentials were not provided."
}

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Invalid Token

Status Code: 401 Unauthorized 
{
  "detail": "Invalid token."
}

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Missing Required Fields

Status Code: 400 Bad Request 
{
  "luminosidade": [
    "This field is required."
  ],
  "nome": [
    "This field is required."
  ]
}

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Invalid Data Type

Status Code: 400 Bad Request 
{
  "luminosidade": [
    "A valid number is required."
  ],
  "media_luminosidade": [
    "A valid number is required."
  ]
}

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MQTT Integration Example

Example from the Raspberry Pi MQTT client: 
# From mqtt-django.py:49-61
if message.topic == topic_ldr:
    nome = "LDR"
    tipo = "Plantas"
    grupo = "Grupo P"
    luminosidade = str(message.payload.decode("utf-8"))
    media_luminosidade = 30
    unidade_medida = "lumen"
    
    luminosidade = {
        'nome': nome,
        'tipo': tipo,
        'grupo': grupo,
        'luminosidade': luminosidade,
        'media_luminosidade': media_luminosidade,
        'unidade_medida': unidade_medida
    }
    
    headers = {'Authorization': 'Token 2d75140c068049278f9cb7d39b1a20f05aecdc56'}
    url_ldr = "http://127.0.0.1:8000/api/ldr/"
    send_luminosidade = requests.post(
        url_ldr,
        headers=headers,
        json=luminosidade
    )

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Serializer Details

The endpoint uses LdrSerializer with depth=1 to include related object details: 
class LdrSerializer(serializers.ModelSerializer):
    class Meta:
        model = Ldr
        fields = '__all__'
        depth = 1

    def create(self, validated_data):
        ldr = Ldr.objects.create(**validated_data)
        ldr.save()
        return ldr
Source: serializers.py:53-62

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Use Cases

  • Monitor light intensity in plant growing environments
  • Track daily light cycles for optimal plant growth
  • Automate grow lights based on natural light levels
  • Ensure plants receive adequate light for photosynthesis
  • Historical light data analysis
  • IoT device integration via MQTT
  • Greenhouse light management

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Light Requirements by Plant Type

Different plants require different light levels:
  • Low Light Plants: 50-250 lumens (Snake plants, Pothos)
  • Medium Light Plants: 250-1000 lumens (Ferns, Philodendrons)
  • High Light Plants: 1000+ lumens (Succulents, Cacti, Tomatoes)
  • Seedlings: 2000-3000 lumens for optimal growth

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Best Practices

  1. Regular Readings: Submit light readings at consistent intervals (e.g., every 10-15 minutes)
  2. Daily Cycles: Monitor throughout the day to track natural light variations
  3. Sensor Placement: Position LDR sensors at plant canopy level
  4. Calibration: Regularly calibrate sensors for accuracy
  5. Baseline Tracking: Use media_luminosidade to track target light levels
  6. Seasonal Adjustments: Account for seasonal variations in natural light

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LDR Sensor Notes

LDR (Light Dependent Resistor) sensors provide analog readings that vary with light intensity. Lower resistance indicates higher light levels. The sensor readings should be converted to lumens or lux for meaningful measurements.

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