daq - DIY Air Quality

DIY Air Quality Monitor by AirGradient integrated with AWS Iot Core & Amazon Timestream, for display in Grafana.

Records & visualises carbon dioxide, particulate matter, temperature, and humidity.

Sections:

1. Estimated cost
2. Assembly
3. Uploading the custom client
4. AWS setup
5. Connect client to AWS
6. Grafana setup

Estimated cost

As of January 2022

The DIY kit can be purchased from AirGradient's shop for between US$46 and US$60 + shipping

AWS IoT Core + Amazon Timestream costs are estimated to be approximately the following:

Service	Link	First month	With 10 years of data
AWS IoT Core	Pricing	US$0.08	US$0.08
Amazon Timestream	Pricing	US$0.22	US$0.45

Assumptions:

• Running in us-east-2
• Limited querying scope and frequency
• Sending data using Basic Ingest
• 24h in-memory retention

Notes:

• Costs will vary depending on usage and prices are subject to change
• You may benefit from using scheduled queries depending on your usage patterns
• There is a 10MB (US$0.0001) minimum charge per query
• In the default configuration, a little more than 2MB is added to Timestream each day

Assembly

Hardware:

• WEMOS D1 mini (ESP8266)
• WEMOS D1 mini display (OLED 0.66 Shield)
• Plantower PMS5003
• Sensair S8
• SHT31

Follow the instructions on https://www.airgradient.com/diy/.

See also Jeff Geerling's video for tips:

Uploading the custom client

AirGradient's client can be uploaded using the Arduino IDE.

This custom client uses the platformio framework to manage the toolchain for building and deployment.

In the client directory:

Build

pio run

Upload

pio run -t upload

The OLED screen should begin displaying information.

Listen to client serial output

pio device monitor

AWS Setup

Please note that Amazon Timestream is only supported in a few AWS regions. See the pricing page for details.

All the infrastructure can be deployed using AWS CloudFormation and the AWS CLI or AWS console.

Configure environment variables:

export AWS_REGION=us-east-2 # ap-southeast-2 when :(
export STACK_NAME=daq

Create the client certificates to connect to AWS IoT Core:

aws iot create-keys-and-certificate \
    --certificate-pem-outfile "daq.cert.pem" \
    --public-key-outfile "daq.public.key" \
    --private-key-outfile "daq.private.key" > cert_outputs.json

Deploy the CloudFormation stack:

aws cloudformation deploy \
    --template-file cloudformation.yaml \
    --capabilities CAPABILITY_IAM \
    --stack-name $STACK_NAME \
    --parameter-overrides MemoryRetentionHours=24 MagneticRetentionDays=3650

aws cloudformation describe-stacks \
    --stack-name $STACK_NAME \
    --query 'Stacks[0].Outputs' > stack_outputs.json

Once the stack has been successfully deployed, configure the certificate.

cat cert_outputs.json stack_outputs.json

Mark as active:

aws iot update-certificate --certificate-id {CERTIFICATE_ID} --new-status ACTIVE

Attach Policy:

aws iot attach-policy --policy-name {POLICY_NAME} --target {CERTIFICATE_ARN}

Attach Thing:

aws iot attach-thing-principal --thing-name {THING_NAME} --principal {CERTIFICATE_ARN}

Connect client to AWS

In client/include/config.h, update the following:

1. Set THING_NAME to the name of the created Thing (eg. daq-Thing-L5KRHBFJORP4)
2. Set ROOM to the human-readable identifier of the room the client is housed in
3. Set ENABLE_WIFI to true
4. Set TIME_ZONE to your timezone
5. Set AWS_TOPIC to the created topic rule name with the included prefix (eg. $aws/rules/TopicRule_0yKDHTposnt5)
6. Set AWS_IOT_ENDPOINT to your AWS IoT Core endpoint (aws iot describe-endpoint --endpoint-type iot:Data-ATS)
7. Set AWS_CERT_CA to the value of AWSRootCA1.pem link
8. Set AWS_CERT_DEVICE to the contents of the created daq.cert.pem file
9. Set AWS_CERT_PRIVATE to the contents of the created daq.private.key file

Then upload the changes:

cd client
pio run -t upload

Connect to the Wi-Fi network beginning with DAQ-, configure the network connection, and reset.

See WiFiManager for more details.

Once the configuration is complete, confirm that the device is sending data to AWS:

$ pio device monitor
*wm:[1] AutoConnect 
*wm:[2] Connecting as wifi client... 
*wm:[2] setSTAConfig static ip not set, skipping 
*wm:[1] connectTimeout not set, ESP waitForConnectResult... 
*wm:[2] Connection result: WL_CONNECTED
*wm:[1] AutoConnect: SUCCESS 
Connecting to server
Connected!
{"device_id":"abb44a","room":"office1","wifi":-71,"pm2":0,"co2":733,"tmp":25.60000038,"hmd":53}
{"device_id":"abb44a","room":"office1","wifi":-72,"pm2":0,"co2":735,"tmp":25.60000038,"hmd":53}
{"device_id":"abb44a","room":"office1","wifi":-72,"pm2":0,"co2":739,"tmp":25.60000038,"hmd":53}

$ aws timestream-query query --query-string 'SELECT * FROM "{DATABASE_NAME}"."{TABLE_NAME}" order by time desc LIMIT 10'
{
    "Rows": [...],
    "ColumnInfo": [
        {
            "Name": "device_id",
            "Type": {
                "ScalarType": "VARCHAR"
            }
        },
        {
            "Name": "room",
            "Type": {
                "ScalarType": "VARCHAR"
            }
        },
        {
            "Name": "measure_name",
            "Type": {
                "ScalarType": "VARCHAR"
            }
        },
        {
            "Name": "time",
            "Type": {
                "ScalarType": "TIMESTAMP"
            }
        },
        {
            "Name": "measure_value::bigint",
            "Type": {
                "ScalarType": "BIGINT"
            }
        },
        {
            "Name": "measure_value::double",
            "Type": {
                "ScalarType": "DOUBLE"
            }
        }
    ],
    "QueryStatus": {
        "ProgressPercentage": 100.0,
        "CumulativeBytesScanned": 1870735,
        "CumulativeBytesMetered": 10000000
    }
}

Grafana setup

See the installation instructions for Grafana.

Add an Amazon Timestream Data Source:

1. In Configuration -> Plugins, install the Amazon Timestream plugin
2. In Configuration -> Data Sources, click Add data source -> Amazon Timestream
3. Pick your preferred method of creating AWS credentials
   1. Create an IAM User and attach the AmazonTimestreamReadOnlyAccess policy

      aws iam create-user --user-name GrafanaTimestreamQuery
      aws iam attach-user-policy --user-name GrafanaTimestreamQuery --policy-arn "arn:aws:iam::aws:policy/AmazonTimestreamReadOnlyAccess"
      aws iam create-access-key --user-name GrafanaTimestreamQuery
      

   2. Use your root credentials and in the Assume Role ARN field, enter the ARN of the QueryRole role in stack_outputs.json
   3. Use your root credentials
4. In the Authentication Provider field, choose either:
   1. Access & secret key and enter the keys directly.
   2. AWS SDK Default or Credentials file and configure your AWS credentials through the filesystem or env variables
5. In the Default Region field, enter the AWS Region
6. Click Save & test

Import the default dashboard:

1. In Create -> Import, click Upload JSON file and select dashboard.json
2. Change the value of Amazon Timestream to your Amazon Timestream Data Source
3. Change the value of Database to the name of your database
4. Change the value of Table to the name of your table
5. Click Import

Acknowledgements

Thanks to AirGradient for creating this awesome DIY kit, providing the example code, and the Gerber + STL files.

Thanks to Jeff Geerling for the video and commentary.