• Low power, dual-core processor
• C/C++ & FreeRTOS support
• WiFi & BLE support

• BM280: temperature, humidity & pressure
• SGP40: Volatile Organic Compounds (VOC)
• LTR390-UV-1: UV
• TSL25911: ambient light (infrared & visible)
• PMSA003I : particle concentration by size

• GT1151: Touch
• Multiple views of live data
• Low power consumption
• User interaction

• Exterior realtime data source
• Free API access
• +200'000 cities

• Influx DB, open source database system
• Time-Series optimized storage
• Lightweight HTTP client

• Get time from the network
• Compute & display local time
• Keep it up-to-date using internal RTC

• 2 wires: clock & data
• Targets have unique address
• Bi-directional, half-duplex
• Simple protocol

• Select target with R/W capability
• Select register
• Send/Read data

• 100kbps usually, up to multiple Mbps
• 120 target devices in 7 bit mode
• Some targets have 10 bit addresses
• Some targets have multi-byte register addresses

• +4 wires: clock, controller-data, target-data, chip-select
• Target have unique address/CS
• Bi-directional, full duplex
• More complex protocol

• Multiple configurations (direct or chained, data lines)
• For the EPD, library is provided by constructor

• 1Mbps usually, ~2x the speed of I2C, up to hundreds of Mbps
• Possibility for multiple data lines to increase bandwidth further
• Target number limited by IO in direct configuration
• Target number limited by delay in chained configuration

• Manually imported certificates
• GET from OWM (JSON)
• POST to Telegram & DB (String)
• JSON handled with arduinojson library

• Base clock runs at 80Mhz
• We set the scaler to run at 1Mhz
• We trigger IRQ every 1 second

• Sensor read, network get & post (Core 0)
• Touch screen IRQ polling & handling (Core 1)
• E-Ink Display refresh & drawing (Core 1)

• After inactivity the device goes into sleep mode
• Wakes up periodically to run measurements
• Returns to standard mode on touch IRQ [WIP]

• List of functions with their run frequency
• On minute tick check if any should have run since last tick
• Not affected by function execution time

(default state for ~30s per 5min, sleep state remaining time: 34mAh in total)