用于机器人和嵌入式应用的基于 ESP32 的开发板_设计_文档_相关文件_下载

<!-- PROJECT LOGO --> [![Stargazers][stars-shield]][stars-url] [![Forks][forks-shield]][forks-url] [![Issues][issues-shield]][issues-url] [![License][license-shield]][license-url] <br /> <p align="center"> <a href="https://github.com/SRA-VJTI/sraboard-hardware-design"> <img src="/documentation/assets/logo.png" alt="Logo" width="200" height="120"> </a> <h3 align="center">SRA Development Board</h3> <p align="center"> ESP32-based Development Board <br /> <a href="https://github.com/SRA-VJTI/sraboard-hardware-design/tree/master/eagle">EAGLE</a> · <a href="https://github.com/SRA-VJTI/sra-board-hardware-design/tree/master/gerber_files">Gerber</a> · <a href="https://github.com/SRA-VJTI/sraboard-hardware-design/blob/master/documentation/images/sra_board_images.md#sra-board-2020-images">Images</a> · <a href="https://a360.co/3c1Rjyv">3D Model</a> </p> <p align="center"> <a href="https://oshpark.com/shared_projects/erADDDjN"><img src="https://oshpark.com/packs/media/images/badge-5f4e3bf4bf68f72ff88bd92e0089e9cf.png" alt="Order from OSH Park"></img></a> </p> # SRA Board 2022 The SRA board is a development board based on ESP32 with on-board peripherals like programmable LEDs and switches, sensor ports for Line Sensor Array and MPU-6050, protection circuit for over-current and reverse voltage and motor drivers.  ## Table of Contents - [SRA Board 2022](#sra-board-2022) - [Table of Contents](#table-of-contents) - [About the Project](#about-the-project) - [Getting Started with a Development Board](#getting-started-with-a-development-board) - [Major Changes for 2020](#major-changes-for-2020) - [Notable problems in the SRA Board 2019](#notable-problems-in-the-sra-board-2019) - [3D Models](#3d-models) - [Milestones](#milestones) - [Contributors](#contributors) - [Acknowledgements and Resources](#acknowledgements-and-resources) - [License](#license) ## About the Project - This development board is used for the [Wall-E](https://github.com/SRA-VJTI/Wall-E_v2.1) and [MARIO](https://github.com/SRA-VJTI/ROS-Workshop-2.1) workshops conducted by [SRA](https://github.com/SRA-VJTI). - Designed using EAGLE. The schematic and board files are [here](https://github.com/SRA-VJTI/sraboard-hardware-design/tree/master/eagle). - Resources for [previous work](https://github.com/SRA-VJTI/PCB-Schematics-and-Layouts/tree/master/WallE-2.1%202018%20Dev%20Brd). For more details of the SRA board 2019, checkout this [link](https://github.com/SRA-VJTI/sraboard-hardware-design/blob/master/documentation/assets/sra-board-2019.pdf). - The SRA board 2020 images can be found [here](https://github.com/SRA-VJTI/sraboard-hardware-design/blob/master/documentation/images/sra_board_images.md#sra-board-2020-images). ## Getting Started with a Development Board <p align="center"> <img width="460" height="300" src="/documentation/assets/boards_compare.png"> </p> In general, every development board has the following basic features: - ### Power Supply Unit - Microcontrollers (MCUs) usually run on 3.3V or 5V while input to a development board is normally 12V for motor control. - So, a *power* section which converts this 12V to standard levels like 5V/3.3V for MCU and sensors is present. - The previous edition of the SRA board (2019) used the LM7805 linear voltage regulator, for stepping down from 12V to 5V; this powered the ESP32. - Further, this 5V was converted to 3.3V using the LD33 linear voltage regulator, used by the sensor port. - ### Motor Driver - Motors usually run on 12V and MCU output is generally 5V/3.3V. So, an external motor driver circuitry is required to control motors according to the MCU input. - The SRA Board 2019 used the L298N IC for motor-control, which is a BJT-based H-Bridge motor driver. - ### Sensor Port - According to the external sensor types, usually development boards have onboard sensor ports where the sensors can be connected easily using FRC connector. - The SRA Board 2019 had two sensor ports - one for a LSA (line sensor array) and the second for the MPU6050. - ### Protection against [Reverse Voltage](https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjc8aaX1c3rAhXXXSsKHXphBgQQFjABegQICxAD&url=https%3A%2F%2Fwww.ti.com%2Flit%2Fpdf%2Fslva139&usg=AOvVaw0Qbub75JJ986MzLv6FYWKE) and Over Current - The SRA Board 2019 used diodes for reverse voltage protection in the power-line. - For the overcurrent protection of MCU and motor driver circuit, fuses of 300mA and 3A were used respectively. - ### Programmable Switches and LEDs - Every development board should have some programmable switches and LEDs for testing, control and debugging purposes. - The previous edition had a pair of programmable switches and programmable LEDs each. - ### Power Switch - The SRA Board 2019 had a power switch for the motor driver, using which power supply to the motor driver can be toggled. Similarly, there was a switch for the ESP32 MCU. > Now that we covered basics of development boards, let us talk about the changes made in the new design. ## Major Changes for 2020 | Feature | SRA Board 2019 | SRA Board 2020| |:----:|:-------:| :-----: | |[12V to 5V](#7805-5v-linear-regulator-to-lm2596-buck-convertor) | LM7805 Linear Regulator | LM2596 Buck Convertor | |[5V to 3.3V](#ld33-33v-to-ams1117)| LD33 | AMS1117 | |[Reverse Voltage Protection](#reverse-voltage-protection-diodes-to-p-mosfet) | Diodes | P-MOSFET | |[Motor Driver](#l298n-to-tb6612fng)| L298N| TB6612FNG| |[No. of Motor Channels](#motor-driver-modes)|2|4| |[No. of Switches](#moving-back-to-the-vintage-bar-graph-leds-and-more-switches)|2|4| |[No. of LEDs](#moving-back-to-the-vintage-bar-graph-leds-and-more-switches)|2|8| - ### **7805 (5V linear regulator) to [LM2596 Buck Convertor](https://www.youtube.com/watch?v=m8rK9gU30v4)** - The greater efficiency, output current and reliability of LM2596 were the reasons for this change. - The efficiency of LM2596 is up to 92% which is significantly better than 7805. The LM2596 can provide current up to 3A, so the MARIO workshop manipulator can now be run using onboard regulator. - ### **LD33 (3.3V) to [AMS1117](http://www.advanced-monolithic.com/pdf/ds1117.pdf)**: - The previous edition used the LD33 IC to step down from 5V to 3.3V; several discussions resulted in the shift to more compact, reliable AMS1117(SOT-23) linear voltage regulator. (_AMS1117 is used in the ESP32-DevKitC V4 module_) - ### **Reverse voltage protection: Diodes to P-MOSFET** - Diodes in series to the power line are inefficient as compare to a P-MOSFET. Dut to the usage of high-rated motors, it was difficult to manage the diode size and the current rating. (_As the current rating of diode increases, its size also increases._) - So, the new edition uses the P-MOSFET instead of a diode, which is more efficient and can handle more current. - ### **L298N to [TB6612FNG](https://dronebotworkshop.com/tb6612fng-h-bridge/)** - L298N is a BJT-based H-bridge motor driver but it is less efficient as compared to the new MOS-based TB6612FNG. - The detailed comparison is shown below. As you can see the efficiency of TB6612FNG can reach up to 91-95% which is significantly higher than the 40-70% efficiency of L298N. - The only drawback of TB6612FNG is the less continuous current which is equal to 1.2A. So, for higher current capacity motors, two TB6612FNG are given on the board, which can be used in parallel mode to double the current capacity to 2.4A. <p align="center"> <img width="460" height="300" src="https://i1.wp.com/dronebotworkshop.com/wp-content/uploads/2019/12/TB6612-vs-L298N.jpeg?w=768&ssl=1"> </p> - ### **Motor Driver Modes** - The new edition has 2x TB6612FNG motor drivers which allow a maximum of 4 motors to be controlled. This motor driver is characterized by its