Fork of SunTracker_BLE by ST Expansion SW Team


The SunTracker is a demo application running on ST Nucleo-F401RE stacking a set of ST X-NUCLEO expansion boards.
Main features provided are:

  • A solar panel follows the light source, orienting the panel in order to achieve the best panel efficiency.
  • Orientation is controlled thanks to a couple of VL6180X FlightSense light sensors mounted on a X-NUCLEO-6180XA1 expansion board and driven by X-NUCLEO-IHM01A1 controlled stepper motor acting as actuator to orientate the panel.
  • The system features a progressive control on the stepper motor in order to modulate the panel rotation speed according to the light angle.
  • The application is also able to control the panel productivity reading the panel voltage through an ADC and proving feedback on the local display.
  • A manual orientation is possible by using the accelerometer on a X-NUCLEO-IKS01A1 expansion board that, according on board tilt, controls the speed and the rotate direction.
  • A remote control is available using a X-NUCLEO-IDB04A1 or a X-NUCLEO-IDB05A1 Bluetooth Low Energy expansion board. Remote control software is here.


Working Status

  • SunTracker has 3 working status visible on FlightSense display and switchable by pressing the User Button:

Status 0 (Idle)

  • Motor: Free Turning
  • Display: Waiting for User Button

Status 1

  • Motor: Driven by Light
  • Display: Direction and Light Intensity = Direction and Motor Speed

Status 2

  • Motor: Driven by Light
  • Display: Solar Panel Efficiency

Status 3

  • Motor: Driven by Accelerometer
  • Display: Direction and Accelerometer Intensity

Server Startup

  • When you plug the power supply, the word ‘PUSH’ is shown on display.
  • You can manually rotate the structure to assign the ‘Zero Point’. Then press the User Button to launch the application.
  • The display will show this status, which means that the structure is oriented to maximize the efficiency of the solar panel.
  • If there is a light displacement, the structure will rotate, left or right, to follow the light source and on display is shown the direction and the speed.
  • You can press the User Button to show the panel efficiency with 4 digits that represent the range from 0v (0000) to 3,3v (3300).
  • Further pressing the User Button you will manual rotate the panel by tilt the Server or Client accelerometer depending by BLE connection.

Client Startup

  • The Client application can remotely control the User Button and the Accelerometer functions.
  • Power on the Client AFTER the Server, it will automatically search for the SunTracker and will establish a BLE connection.
  • The Green Led on Nucleo Client board will be powered on.

Rotation Features

  • It has been implemented a block of rotation to avoid cables twist.
  • The blocking point can be set in the firmware by changing a constant.
  • You can manually rotate the structure to assign the ‘Zero Point’ before press the User Button to launch the application.
  • The system features a progressive control on the stepper motor in order to modulate the rotation speed according to the light or accelerometer angle.

List of Components


  • Stepper Motor 400’’ (Part Number 5350401) - To orientate the Mechanical Structure.
  • Solar Panel 0.446w (Part Number 0194127) - To capture sunlight and generate electrical current.
  • Power Supply 12v (Part Number 7262993) - To provide power supply at the Stepper Motor.
  • Flat Cable 6 ways (Part Number 1807010) - To plug VL6180X-SATEL with X-NUCLEO-6180XA1 (60cm length each x2).
  • Cable Connector (Part Number 6737694) - To plug the Flat Cable (x4).
  • Power Connector (Part Number 0487842) - To provide Power Supply to X-NUCLEO-IHM01A1.

CLIENT SunTracker_BLE_Remote


Find here the STL files to print with a 3D printer.






Nucleo ADC + Solar Panel

Connect Solar Panel cables to Nucleo Morpho PC_3 (white) and Nucleo Morpho GND (black). Connect a capacitor 10uF between PC_3 and GND to stabilize its voltage value shown on display.

EasySpin (L6474) + BLE

Hardware conflict between EasySpin DIR1 and BLE Reset, both on same Arduino Pin PA_8. Disconnect PA_8 between EasySpin and Nucleo by fold EasySpin Pin. PB_2 has been configured as EasySpin DIR1 in the firmware . Connect Nucleo Morpho PB_2 to FlightSense Arduino PA_8 by a wire.

FlightSense Satellites

In case of instability with I2C due to long flat cables, solder 4 SMD capacitors 47pF on FlightSense board in parallel between R15, R16, R17, R18 and plug 2 capacitors 15pF between FlightSense Arduino PB_8 and PB_9 to GND pin to cut-off noises over 720 KHz.

Arduino & Morpho Pinout

/media/uploads/fabiombed/arduino_pinout.png /media/uploads/fabiombed/morpho_pinout.png

--- a/main.cpp	Fri Feb 26 14:55:48 2016 +0000
+++ b/main.cpp	Thu Mar 03 16:32:10 2016 +0000
@@ -146,7 +146,7 @@
     if (Display>2)  { Display=0; }
     if (start==0)   { start=1; }
-    printf("PUSH Display %d\r\n", Display);
+    printf("PUSH Display %d\r\n", Display+1);
@@ -235,16 +235,13 @@
 bool Initialization(void)
-    // Initializing MEMS Component
-    mems=X_NUCLEO_IKS01A1::Instance(&dev_i2c);
-    accelerometer = mems->GetAccelerometer();
+    dev_i2c.frequency(100000);     // at 200KHz or 400KHz doesn't work
     // Initializing Babybear Component
-    //board=X_NUCLEO_6180XA1::Instance(&dev_i2c);
-    board=X_NUCLEO_6180XA1::Instance(&dev_i2c, NC, NC, NC, NC);
+    board=X_NUCLEO_6180XA1::Instance(&dev_i2c, PA_4, PA_4, PA_4, PA_4); // Don't use NC because it doesn't set InterruptIn correctly
     if(status) VL6180x_ErrLog("Failed to init the board!\n\r");
@@ -261,8 +258,18 @@
     status_l=board->sensor_left->StartMeasurement(als_continuous_polling, NULL, NULL, NULL);
     status_r=board->sensor_right->StartMeasurement(als_continuous_polling, NULL, NULL, NULL);
+    printf("Init Babybear OK\r\n");
+    // Initializing MEMS Component
+    mems=X_NUCLEO_IKS01A1::Instance(&dev_i2c);
+    accelerometer = mems->GetAccelerometer();
+    printf("Init MEMS OK\r\n");
     // Initializing Motor Component
     motor = new L6474(D2, D8, PB_2, D9, D10, dev_spi); // D7 conflict with BNRG_RST (when motor change direction 0-1 reset BLE)
                                                        // Used Morpho PB_2 and made HW wiring
@@ -277,6 +284,8 @@
     motor->SetMaxSpeed(SET_MAX);        // Variable by Light/Mems Sensors
+    printf("Init Motor OK\r\n");
     return true;
@@ -398,12 +407,12 @@
     // Printing to the console
     printf("SunTracker by Fabio Brembilla\r\n\n");
     printf("Initialization OK (Line %d)\r\n", __LINE__);    
-    //BLE_Initialization();
-    //printf("BLE_Initialization OK (Line %d)\r\n", __LINE__);  
+    BLE_Initialization();
+    printf("BLE_Initialization OK (Line %d)\r\n", __LINE__);  
     printf("Wait Push Button\r\n");
@@ -420,7 +429,7 @@
     motor->Enable(); // To put the motor on hold execute CmdEnable
-    //static int INTLOOP=0;
+    static int INTLOOP=0;
     // Main Loop
@@ -430,11 +439,11 @@
+        INTLOOP++;
+        if (INTLOOP==100) { p_customsensorservice->sendEnvPosition(rand(),0); printf("Read BLE\n\r"); INTLOOP=0; }
-        //INTLOOP++;
-        //if (INTLOOP==100) { p_customsensorservice->sendEnvPosition(rand(),0); printf("Read BLE\n\r"); INTLOOP=0; }
-        //p_BLEdev->waitForEvent();
+        p_BLEdev->waitForEvent();