MAXimator Expander


MAXimator Expander is an extension module with an embedded temperature sensor, 7-segment displays, keyboard and multi-colored LEDs. The board is dedicated to work with MAXimator


Basic features and parameters
  • STLM20W87F temperature sensor from STMicroelectronics
  • Four 7-segment displays, multiplex controlled
  • Embedded 74LVC2244A (buffer powered displays)
  • Two multi-colored (RGB) LEDs WS2812B type
  • Embedded two user buttons and reset button
  • Mounting holes 3mm
  • Module size: 5 mm x 55mm x 19mm

Board is not compatible with Arduino!

Standard equipment
Code Description
MAXimator Expander
  • Assembled and launched module

Electrical schematic

View of board
Pcb exp.png

Temperature sensor

On MAXimator Expander board is placed integrated STLM20 temperature sensor with an analog signal output. The signal output is available on the A0 line. The output voltage of chip represents the measured temperature, according to the transfer function:

Vo =–11.69 (mV/°C)*T+1.8663V


T – temperature measured by sensor

Vo – output voltage

Measured temperature has a value:

T=(1.8663−Vo) / 0.01169


7-segment displays

On board are mounted four 7-segment LED displays, multiplex-controlled via 74LVC2244A chip.

Pcb leddis7.png

Line LED segment
D0 segment A
D1 segment B
D2 segment C
D3 segment D
D4 segment E
D5 segment F
D6 segment G
D7 segment DP
D8 cathode DS1
D9 cathode DS2
D10 cathode DS3
D11 cathode DS4



Multi-colored LEDs (RGB)

Embedded multi-colored WS2812 diodes allow for displaying colors in more than 16.7 million shades, diode control is in series - with one signal line it is possible to control a series of such diodes. The D12 line supplies the control signal to the LED1 input, its output is connected to the LED2 input.




Board has two user buttons (marked "L" and "R") and a system reset button. Signal lines D14 and D15 (to which the "R" and "L" buttons are connected) are pulled up to the supply voltage (+5V). Reset button (RES) is connected to the nRST line, pressed to connect the line to the ground.




Key Line Default state
„L” (S1) D15 Pull up to power supply (+5 V)
„R” (S2) D14 Pulled up to power supply (+5 V)
RES (S3) nRST Disconnected