1. Advanced Micromouse Hardware Design
Lecture 4
Advanced Micromouse Hardware Design

2. Lecture Outline Microcontroller Power System Peripherals
Sensor System: IR emitters and receivers
Motor Controller
Gyro
Buzzer
Display
Voltage Meter
LEDs
Push Button
Reset Button

3. Microcontroller STM32F405RGT6 – 64 pins
Timers - Generate PWM signals to motor, buzzer
GPIOs – LEDs, IR emitters, push button
USART – Allows “printf” to display on a terminal
SPI – Prints data on alphanumeric display
ADC – Convert analog voltage to a digital number
1 MB Flash – Store maze info

4. Microcontroller Pins
Multi-function pins

5. Power System - Microcontroller
Power Supply Schemes:
VDD = 1.8 to 3.6 V: external power supply that will supply the voltage for GPIOs (Futura Mouse: 3.3 V)
VDDA = 1.8 to 3.6 V: external analog power supply for ADC, DAC, Reset blocks, RCs and PLL (Futura Mouse: 3.3 V)
VBAT = 1.65 to 3.6 V: power supply for RTC, external 32 kHz oscillator, backup registers (Futura Mouse: 3.3 V)
VSSA = GND for VDDA; VSS = GND for VDD
VCAP: connect 2.2 microFarad ceramic cap between this pin and GND (External capacitor that decouple power supply)

6. Power System

7. Power System – Power Supply
Fully Charged Battery: 8.4 V (2 x 4.2 V)
Motor Controller System (Level shifter + H-Bridge)
5V regulator 5V
Encoders, IR Emitters (anode “+”), Alphanumeric Display
3.3 V regulator
3.3 V
Microcontroller, Buzzer, USART, push buttons
3.3 VA (analog circuits)
IR Receivers, Gyro

8. 8.4V Power - Battery

9. Power 5V

10. Power 3.3V and 3.3VA

11. IR Emitter - Front (SFH4545)

12. IR Emitter – Diagonal SFH4545

13. IR Receiver (TEFT4300)

14. IR Sensor Pulsing Timing
Delay between each sensor reading until all residues are gone

15. Motor Driver
H-Bridge IC
Level Shifter IC

16. Gyro

17. Buzzer Buzzer behaves like an inductor
Diode is used to prevent inductive
kickback

18. Display

19. Voltage Meter
Keep track of the battery voltage to protect the battery from over discharging

20. LED 2 ways to control LED with MCU
The one on left is easier for wiring since ground is easier to find
The way to the right is better in terms of power, since power is not drawn from the MCU
Futura Mouse uses left scheme

21. Push Button
-Futura Mouse uses right scheme

22. Boot0 Button
For new MCUs, bootloading must be done just once via USART
Boot mode must be entered first before bootloading
Figure 2 shows how to save one button
Figure 1
Figure 2

23. System memory boot mode
Bootloader is stored in the system memory (ROM).
To enter boot mode, set Boot0 high by holding down on the Boot0 push button,
then push the reset button. Boot1 should be connected to GND.
- Using USART, load application programs into FLASH.

24. Boot0 and Boot1

25. Reset Button
Use Reset to reset the state of the mouse, instead of the power ON/OFF switch
This button is IMPORTANT for entering system memory boot mode
Reset is active low

26. References
STM32F405 MCU datasheet
Info about pull-up and pull-down resistors
Info about pin input/output modes (i.e. push-pull, open-drain)
Info about inductive kickback
Info about decoupling capacitors (filters)
Info about phototransistor circuits (IR receiver)