SimpleFOC Lesson 2: Basic Testing of Makerbase Motor Driver

This section teaches Arduino IDE navigation and fundamental programming concepts. The IDE includes File menu for project management, Library Manager for adding external libraries, Tools menu for board and port selection, and Serial Monitor for debugging. Arduino programs use two main functions: void setup() for one-time initialization and void loop() for continuous execution. Pin configuration requires pinMode() to set pins as INPUT or OUTPUT. Digital output control uses digitalWrite() with HIGH (5V) or LOW (0V) states. The delay() function creates time delays in milliseconds (1000ms = 1 second). LEDs require current-limiting resistors to protect them from excessive current and extend operational lifespan.

Arduino is a simple, low-cost board that enables users to work with microcontrollers. The microcontroller serves as the brain, found in many devices. Arduino Uno contains: USB port, power jack, 5V regulator, reset button, and analog input pins (A0-A5). The ATmega328P microcontroller has 2KB SRAM, 32KB Flash memory, and 1KB EEPROM. Arduino is open source, allowing design modifications. The Arduino IDE provides a comprehensive interface for development: code editor with syntax highlighting, compile/upload buttons, Tools menu for board selection, Sketchbook for project organization, and Serial Monitor for debugging. Shortcuts like Ctrl+Z, Ctrl+U, and Ctrl+R streamline the development process. The IDE automatically detects connected boards and COM ports.

The Arduino IDE provides a user-friendly interface for programming microcontrollers. Setup involves selecting the correct board type and COM port, with third-party boards requiring additional USB serial drivers. Arduino programming extends C language with simplified syntax. Every program requires two essential functions: setup() runs once for initialization, and loop() runs continuously for main logic. Functions use curly braces and require semicolons. pinMode() configures pin direction, digitalWrite() controls output states, and delay() manages timing. The built-in LED variable (LED_BUILTIN) ensures code portability across different Arduino models.

Arduino programming uses C-based sketches written in a simplified version of C. The Arduino IDE provides tools for writing, compiling, and uploading code to the board. The IDE includes a Serial Monitor for viewing output. Arduino programs have only two main constructs: setup() (runs once at startup) and loop() (runs continuously). Built-in functions include pinMode() for configuring pins as input or output, digitalWrite() for writing values to digital pins, and delay() for introducing time delays in milliseconds. Libraries are pre-written code that simplifies working with sensors and components, handling complex communication protocols and data interpretation.

This comprehensive section covers the foundational concepts of microcontroller programming using ATtiny 85, ATtiny 45, and ATmega 328P. The video explains how to build a programmer (quemador) that eliminates the need for external crystal oscillators and capacitors. Key topics include accessing the Arduino IDE for downloading programs and Gerber files for PCB manufacturing, understanding pin configurations for SPI programming (pins 13, 12, 11 for MISO, MOSI, SCK), and the role of the reset pin. The section details configuring the Arduino as an ISP programmer by downloading the ArduinoISP example, selecting the appropriate serial port, and verifying compilation. It also covers installing additional boards through the Board Manager, creating the necessary hardware folder structure, and copying board files. The video demonstrates burning the Arduino bootloader onto microcontrollers and programming them with internal 8 MHz oscillators.

I2C (Inter-Integrated Circuit) and SPI (Serial Peripheral Interface) enable communication with external sensors and peripherals. I2C uses two wires: SDA (data) and SCL (clock), implemented on Uno via pins A4 and A5. Only one I2C module exists, so avoid using both SDA pins simultaneously. SPI offers faster data transfer than I2C but requires more wires: SCK (clock), MISO (receive), MOSI (transmit), and SS/CS (chip select) per device. On Uno, these correspond to pins 13, 12, 11, and 10 respectively. SPI is not recommended for long wire runs due to signal degradation. Both protocols require power and ground connections. Choose I2C for longer distances and SPI for higher speed applications within short ranges.

Communication protocols are standardized rules enabling electronic devices to exchange data reliably. They serve as a common 'language' allowing microcontrollers, sensors, and interfaces to understand each other. Protocols ensure data is transferred accurately without errors, which is critical for correct system operation. Standardization is essential because multiple manufacturers produce chips with communication interfaces, making interoperability possible. Serial communication transfers data one bit at a time over a single wire, while parallel communication transfers multiple bits simultaneously over multiple wires. UART (Universal Asynchronous Receiver/Transmitter) enables asynchronous serial communication without requiring a shared clock signal, using two wires: TX and RX, plus ground. UART data frames consist of a start bit, 8 data bits (LSB first), optional parity bit, and stop bit. I2C (Inter-Integrated Circuit) is a synchronous serial communication protocol using two wires: SDA and SCL. It supports multiple masters and slaves, with each slave having a unique 7-bit address. I2C uses open-drain configuration with pull-up resistors. Speed modes include Standard Mode (100 kbps), Fast Mode (400 kbps), and Fast Mode Plus (1 Mbps). SPI (Serial Peripheral Interface) is a synchronous serial communication protocol using four wires: MOSI, MISO, SCK, and SS. SPI supports full-duplex communication with high-speed data transfer (up to 10 Mbps or more). SPI communication begins when the master selects a slave by pulling its SS line low, then generates clock pulses on the SCK line for data transfer.

Serial transmission sends data one bit at a time over a shared bus, offering advantages over parallel transmission including longer distances, higher throughput, and support for more nodes; three common low-speed serial protocols are UART (asynchronous, two-wire, uses start/stop bits and optional parity for framing data), I2C (synchronous, two-wire, master-slave architecture with address-based communication and acknowledgment bits), and SPI (synchronous, four-wire, full-duplex with separate chip select lines for addressing slaves); each protocol defines how bits are formatted into messages and the rules for exchanging data between devices.

This video explains three fundamental serial communication protocols used in microcontroller applications: UART (Universal Asynchronous Receiver Transmitter) uses two wires (TX/RX) with start/stop bits and a shared clock, requiring configuration of baud rate and data format; I2C (Inter-Integrated Circuit) uses two wires (SDA/SCL) with a clock line for synchronization and slave addressing, allowing multiple devices on one bus; SPI (Serial Peripheral Interface) uses four wires (MOSI/MISO/SCK/CS) for full-duplex communication without slave addressing, offering higher speed and lower power consumption but limited range. Each protocol balances trade-offs between connection count, speed, complexity, and range.

I²C uses two lines (SDA for data, SCL for clock) to connect multiple devices on a shared bus, requiring unique device addresses. SPI uses four lines (MOSI, MISO, SCK, and CS) with a dedicated CS line per device, enabling faster communication but consuming more pins. Both protocols allow the processor to communicate with sensors (IMU, barometer) and storage devices (SD card, flash chip) efficiently.

This section covers the core definitions and characteristics of open loop and closed loop systems. An open loop system operates without a feedback path from output to input, meaning the output is not measured or compared with a reference set point. Control action is independent of the desired output, making these systems simple in design, less costly, easier to install, and requiring minimal maintenance. In contrast, a closed loop system incorporates a feedback path with a controller that continuously monitors output using sensors, compares it against a set point, and adjusts the input based on the error signal to minimize the gap between actual and desired output. Closed loop systems offer better accuracy but require more complex circuitry, higher costs, and regular maintenance.

Control systems are classified into open loop and closed loop types. Open loop systems have input, controller, and process with no feedback path connecting output back to controller. Closed loop systems include a feedback path where output is measured by a measuring element and fed back to the controller. The controller compares input with feedback to generate an error signal, which modifies the input to achieve desired output. This automatic adjustment distinguishes closed loop systems from open loop ones.

A control system is a system with a controller that produces a controlled output, where the key distinction between open loop and closed loop systems lies in feedback: open loop systems have a controlling mechanism independent of the output (no feedback), while closed loop systems have a feedback mechanism that depends on the output. The closed loop transfer function for a negative feedback system is given by G(s)/(1 + G(s)H(s)), where G(s) is the forward path gain and H(s) is the feedback path gain. This feedback structure makes closed loop systems less sensitive to parameter variations in the forward path, which is why they are preferred for reliable control applications.

Open-loop systems apply input without feedback, while closed-loop systems use feedback to compare actual output with desired output. Open-loop systems have a simple input-to-output structure with no feedback path. Closed-loop systems include a feedback mechanism that continuously monitors output and adjusts control actions to minimize error. The key difference is that closed-loop systems can compensate for disturbances and maintain desired output despite external variations, making them more suitable for applications requiring precise control.

A control system is an arrangement of components that performs a specific task by transforming input through a process to produce output; it can be classified into open loop systems (which operate without feedback and assume output meets requirements) or closed loop systems (which use feedback to automatically adjust and maintain desired output).

Resistors are fundamental components in switched power supplies, serving multiple critical functions. Voltage division circuits monitor AC input voltage through series resistor networks for brown-out protection (BNO pin), preventing IC damage when voltage falls below safe thresholds. High-value resistor networks (1.5MΩ+) supply the VCC pin, limiting current to microampere levels while charging the VCC capacitor. Current sense resistors (shunt resistors, typically <1Ω) monitor circuit current by creating proportional voltage drops (V = I × R) for overload protection. Component designation systems use standardized codes: 'R' for resistors, 'U' for primary circuit ICs, and 'S' for secondary circuits. Understanding these resistor applications is essential for power supply design and troubleshooting.

The overcurrent protection circuit uses a voltage divider (221 ohm and 3.74K ohm resistors) to create a 0.3V reference voltage from a 5V source. The current sensing resistor (0.02 ohm) converts current to voltage using Ohm's Law (V = I × R). For 15A maximum current, this produces exactly 0.3V. The comparator compares this voltage against the reference. When current exceeds 15A, the input voltage exceeds the reference, causing the output to generate a 5V pulse that interrupts the power IC.

This section covers voltage, current relationships, and electrical safety fundamentals. Voltage represents potential difference between points in an electric field, calculated as the integral of electric field along a path, measured in volts (named after Volta). Reference points establish voltage measurements: a 9-volt battery with 0V reference shows potentials of 0V, 3V, 6V, and 9V at different points. Electric current I = dQ/dt represents charge flow rate, with Q = I×t for constant current. One ampere equals one coulomb per second. Electrical safety depends critically on voltage type and current path: DC becomes dangerous above 120V, AC above 50V at 50Hz. With typical body resistance of 1kΩ, 120V DC produces ~120mA, sufficient to cause ventricular fibrillation. Always assume stored energy in capacitors even when equipment appears powered off.

In a power supply circuit, current sensing can be achieved by placing a small sense resistor in series with the load. When current flows through this resistor, a voltage drop develops across it proportional to the current. This voltage is divided among multiple resistors in the circuit according to their resistance values—higher resistance results in higher voltage drop. By monitoring this divided voltage, the circuit can detect changes in load current.

The current sensing circuit uses a comparator IC with voltage dividers to measure current. The voltage divider is created using a 4.4V reference (pin 5) and a voltage divider network. The expected voltage at the divider output should be approximately 370mV, but in this case, it was reading 307.5mV, indicating a fault in the voltage divider circuit.