The chosen SoC for this application was the Texas Instruments CC2538, that combines a powerful ARM Cortex-M3-based MCU system with up to 32KB on-chip RAM and up to 512KB on-chip flash with a robust IEEE 802.15.4 radio, all in a 8x8mm² QFN56 footprint.
Here are some of it's characteristics:
- Up to 32-MHz clock speed;
- Supports On-Chip Over-the-air Upgrade (OTA);
- Supports Dual ZigBee Application profiles;
- cJTAG and JTAG debugging;
- Low power consumption:
- 24mA TX current;
- 20mA RX current;
- 1.3 µA in Power Mode 2 (Sleep);
- 0.4 µA in Power Mode 3 (Deep Sleep);
- High memory density:
- 512Kbyte, 256Kbyte or 128Kbyte flash memory;
- 32Kbyte RAM memory
- 2.4-GHz IEEE 802.15.4 Compliant RF – I2C Transceiver;
- Receiver Sensitivity of –97 dBm;
- Robustness to Interference With ACR of 44 dB;
- Programmable Output Power up to 7 dBm
- 4 × General-Purpose Timers (Each 32 bit or 2 x 16 bit);
- 32-Bit 32-kHz Sleep Timer;
- 12-Bit ADC With 8 Channels and Configurable resolution;
- Battery Monitor and Temperature Sensor;
- USB 2.0 Full-Speed Device (12 Mbps);
- 2 × SPI;
- 2 x UART;
- 32 General-Purpose I/O Pins;
- Watchdog Timer;
The EPOSMote III board have one red LED that can be used through the PC3 (1, EXP2) GPIO.
The EPOSMote III board have one push-button, used to reset the system.
The ST' LSM330 is a low power 3-axis accelerometer (250µA in measurement mode and 10µA in standby mode) and giroscope (6.1mA in measurement mode, 2mA in sleep mode and 5µA in power-down mode) with a SPI/I2C interface. It has 8-bit resolution and can measure from -16G to 16G.
The Silicon Labs' Si7020 is a versatile temperature and humidity sensor, operated via I2C, with high precision (±4% Relative Humidity (max), 0-80% Relative Humidity) and accuracy (±0.4°C (max), –10 to 85°C). It has a low-power consumption (150µA active current and 60nA standby current), packed in a 3x3mm² DFN enclosure.