Fejemis Teensy

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Drive Teensy

Block diagram with all interfaces and interface protocol

Front Teensy

Block diagram with all interfaces and interface protocol

Software structure

Figure: The Teensy software is structured with a main loop and a number of units. After reset all units are initialized in a setup function, after that the main loop is entered. The main loop services the USB and send commands to the units for decoding. At regular intervals, the sample clock tick, all units are called to execute any sample time function. Most units are interfaces to external devices such as IMU, motor drive or distance sensor. There is further support units for e.g. control.

Setup - loop overview

The setup and loop structure follows the Arduino sketch format. The file is a C++ file as the compilation is using a Makefile rather then the Arduino IDE.

The main file (main.cpp) code has this structure (shortened for clarity)

void setup()   // INITIALIZATION
{
 usb.setup();
 led.setup();
 imu.setup();
 enc.setup();
 sensor.setup();
 motor.setup();
 state.setup();
}
void loop(void)
{
 usb.send("# Starting main loop\n");
 while ( true ) 
 { // main loop
     usb.tick();     // incoming command service
   if ( startNewCycle ) // start of new control cycle
   {
     imu.tick();     // for heading estimate
     sensor.tick();  // AD converter, e.g. battery maintenance
     irdist.tick();  // distance sensor
     enc.tick();     // wheel encoder and odometry
     state.tick();   // e.g. emergency stop
     control.tick(); // feedback control
     motor.tick();   // motor control
   }
 }
}

Module structure

One file one interface.

Subscription

Standardized setup of data subscription

Command decode

On-line help.

Configuration save

Use of configuration flash.

Update tick

Sample rate and sensor calculation