MIKROE Spectrometer Click features an 11-channel spectrometer for spectral identification and color matching applications. This Click board™ features the AS7341 from AMS-AG, whose spectral response is defined in the wavelengths from approximately 350nm to 1000nm. Control and Spectral data access are implemented through a serial I2C interface with very a low power consumption. AS7341 also integrates a dedicated channel to detect 50Hz or 60Hz ambient light flicker. It has many features that make it attractive for various applications such as spectral measurement, reflective object color detection, color measurement, and as ambient light flicker detection.

Spectrometer Click uses the AS7341 IC, 11-Channel Spectral Sensor Frontend from AMS-AG. This IC features 6 independent optical channels with a dedicated 16-bit light-to-frequency converter. Gain and integration time of the 6 channels can be adjusted with the serial interface. Wait time can be programmed to automatically set a delay between two consecutive spectral measurements and to reduce overall power consumption. The other available channels can be accessed by a multiplexer (SMUX) connecting them to one of the internal ADCs. Also features a 4x4-photodiode array. On top and below the photodiode array there are two photodiodes with dedicated functions such as flicker detection and near-infrared response.

This Click board includes an LDO AP7331 to provide the 1.8 V supply voltage for the AS7341 and 3 N-Channel MOSFET BSS138 for voltage level translation. The AS7341, interrupt-driven IC, is controlled and monitored by registers accessed through the I²C serial interface. These registers provide device control functions and can be read to determine device status and acquire device data. The device supports 7-bit chip addressing and both standard and full-speed clock frequency modes. It possesses 8 optical channels distributed over the visible spectral range, plus clear and NIR channel to accurately measure and match colors, and configurable sleep mode. The device also integrates a dedicated channel to detect 50Hz or 60Hz ambient light flicker. The flicker detection engine can also buffer data for calculating other flicker frequencies externally.

Upon power-up, the Spectrometer Click initializes. During initialization (typically 200μs), the device will deterministically send NAK on I²C and cannot accept I²C transactions. All communication with the device must be delayed and all outputs from the device must be ignored including interrupts. After initialization, the device enters the SLEEP state (the internal oscillator and other circuitry are not active resulting in ultra-low power consumption). Once the Power ON bit is enabled, the device enters the IDLE state in which the internal oscillator and attendant circuitry are active, but power consumption remains low. Whenever the spectral measurement is enabled the device enters the ACTIVE state. If the spectral measurement is disabled the device returns to the IDLE state.

This Click board™ can be supplied and interfaced with both 3.3V and 5V supply voltages. The onboard SMD jumper labeled as VCC SEL allows voltage selection for interfacing with both 3.3V and 5V microcontrollers. More information about the AS7341 can be found in the attached datasheet. However, this Click board™ comes equipped with a library that contains easy to use functions and a usage example that may be used as a reference for the development.

• Interface: GPIO, I²C
• Compatibility: mikroBUS™
• Dimensions: 42.9 x 25.4mm
• Input Voltage: 3.3V or 5V
• Supply Voltage: Min. -0.3V, Typ. 1.8V, Max. 2.2V
• Maximum Output Current: Min. -1mA, Max. 20mA
• Operating Temperature Range: Min. -30°C, Max. +85°C
• Spectral Response: Min. 350nM, Max. 1000nM

• Schematic
• AS7341 Datasheet
• mikroSDK
• GitHub