Spectral 3 click
PID:
MIKROE-2961
Weight:
24 g
Spectral 3 click
is a multispectral sensing device, which uses the state-of-the-art sensor IC
for a very accurate near-IR (NIR) sensing. The sensor on the Spectral 3 click provides multi-
spectral sensing in the NIR wavelengths from approximately 610nm to 860nm with the full
width at half maximum (FWHM) of 20nm. Spectral 3 click provides a direct reading of the
six different channels with the 16bit precision, as well as the calibrated reading, that gives
32bit float values with an 8bit biased exponent and a 23bit fraction part, processed through
the Spectral ID engine. The sensor also integrates two programmable LED channels with
constant current drivers, useful for indication and for providing the backlight for the
measured color object.
The onboard sensor has minimal drift over time and with temperature, which makes it very
reliable, even after long periods of time. The integrated temperature sensor compensates
for all the thermal influences from the environment. Equipped with such an advanced
multispectral sensor IC, Spectral 3 click can be used in various spectrometry applications,
used for the product authentication applications, spectral identification, banknote and
document validation, chemical analysis, food, beverage safety, etc. Essentially, for any
professional grade applications that require a high degree of NIR spectral sensing accuracy
and consistency.
How does it work?
The multispectral sensor IC used on the Spectral 3 click is the AS7263, a 6 channel NIR
Spectral_ID device with electronic shutter and smart Interface. This is a very advanced
multispectral sensor, which incorporates a 6 photodiodes array element. Every photo
element is filtered through the Gaussian filters, implemented through the nano-optic
deposited interference filter technology, designed to provide ranges for 6 near-IR spectral
channels: R = 610nm, S = 680nm, T = 730nm, U = 760nm, V = 810nm and W = 860nm, each
with 20nm FWHM. The filter characteristics are tested and measured with the diffused
white light. This technology ensures minimal drift of the readings and temperature
stability. It should be noted that the filter accuracy will be affected by the angle of
incidence, determined by an integrated aperture and the internal microlenses, which
is ±20° for the AS7263 IC.
The measurements from the photo elements are digitized by the 16bit ADC converter and
processed by the Spectral_ID engine. Besides the raw values of the six color elements, the
engine calculates all the calibrated values available on this device and outputs them as
32bit float values. After the specified integration time (2.8ms min), those values are
available in their respective registers and are accessible via the smart high-level UART
interface driven by simple AT commands, or the I2C communication protocol bus. Even the
temperature sensor can be accessed via its register. A complete list of all the available color
coordinates and the registers which hold these values can be found in the AS7263
datasheet.
The sensor data is organized in two banks. The first bank contains readings from the S, T, U
and V photodiodes, while the second bank contains readings from the R, T, U, and W
photodiodes. Different modes allow readings to be made from each bank, as well as the
combinations between these two banks. There is also a mode for one-shot reading when
time-critical or triggered measurement needs to be made. The photodiode letter codes
above, represent the channels of the respective wavelengths (Channel R, Channel S,
Channel T…).
An interrupt can be triggered when the data is ready to be read by the host, depending on
the selected bank mode. If the interrupt is enabled (INT = 1), the INT line is pulled to a LOW
logic level and DATA_RDY bit of the control register is set to 1. The INT line is released
when the control register is read. The DATA_RDY bit will be cleared whenever the
measurement registers are read. The interrupt will be generated after one or more
integrating cycles are completed, depending on the selected bank mode. The INT line of the
AS7263 is routed to the mikroBUS™ INT pin and can be used to trigger an interrupt on the
host MCU. More about bank reading modes and the interrupts can be found in the provided
AS7263 datasheet.
The RESET line of the sensor
is routed to the mikroBUS™ RST pin. If this line is pulled to a
LOW level for more than 100ms, it will reset the device.
The sensor firmware is kept externally, on the auxiliary flash memory IC. The AT25SF041,
an SPI serial flash memory is used for storing the firmware of the AS7263 sensor.
The AT25SF041 IC communicates with the sensor via the SPI lines, internally routed on the
Spectral 3 click.
UART and I2C lines of the AS7263 sensor are routed to the mikroBUS™ respective UART
pins (RX/TX and SDA/SCL). To select which interface will be used to drive the sensor IC,
three onboard SMD jumpers labeled as COM SEL need to be moved either to the left
position (to enable UART), or to the right position (to enable I2C). It should be noted that
all the SMD jumpers need to be moved at once - if some of them are set as UART and some
as I2C, the communication might not be possible at all.
There are two integrated programmable LED drivers on the AS7263 sensor. The first LED
constant current driver can be programmed up to 10mA and it can be used as the status
indicator. It is also activated during the sensor firmware programming. The second LED
driver is intended for driving of the light source for the measurement surface illumination.
It can drive high brightness LED with up to 100mA. Both of these LED drivers are available
through the communication interfaces.
Specifications
Type
Optical
Spectral 3 click can be used in various spectrometry
applications, for the product authentication, spectral
identification, banknote and document validation,
chemical analysis, food, and beverage safety, etc
AS7263, a digital 6-channel spectrometer for spectral
identification in the near IR (NIR) light wavelength range,
with electronic shutter and smart interface, from ams;
AT25SF041, a 4Mb SPI serial flash from Adesto
Technologies
Compact 6-channel near-IR spectrometry solution
realized by the proprietary silicon interference filters,
lifetime-calibrated sensing with no drift over time or
temperature, on-chip data processing, auxiliary
illumination LED drivers, smart UART interface
I2C,UART
Applications
On-board
modules
Key Features
Interface
Input
Voltage
Click board
size
3.3V
L (57.15 x 25.4 mm)
Pinout diagram
This table shows how the pinout on
Spectral 3 click
corresponds to the pinout on the
mikroBUS™ socket (the latter shown in the two middle columns).
Notes
Pin
Pin
Notes
NC
Reset
RST
NC
NC
NC
NC
Power supply
Ground
+3.3V
GND
1
2
3
4
5
6
7
8
AN
RST
CS
SCK
MISO
MOSI
3.3V
GND
PWM
INT
RX
TX
SCL
SDA
5V
GND
16
15
14
13
12
11
10
9
NC
INT
TX
RX
SCL
SDA
NC
GND
Ground
Interrupt
UART transmit
UART receive
I2C Clock
I2C Data
Onboard settings and indicators
Label
LD1
LD2
Name
PWR
IND
Default
-
-
Description
Power LED indicator
Programmable constant current LED indicator
Programmable constant current LED
illuminator
Communication Interface Selection I2C/UART, left
position UART, right position I2C
LD3
DRV
-
JP1
COM.SELL.
Left
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