[Compatible with Arduino Mega 2560] Lengfan Development Board Type A Version 3

###### Looking for other development boards? Please refer to [Miss Xing Yuandai's Development Board Introduction](https://oshwhub.com/article/ICMCU_board_series_guide)
###### Need to burn the BootLoader provided by Arduino for this development board to be compatible with corresponding products or for customized USB configuration? Please refer to [Super detailed: How to burn BootLoader for your Arduino and compatible boards](https://oshwhub.com/article/Write-Arduino-BL)

# Copyright Notice and Other Important Tips

* ![Creative Commons License] * This work is compatible with the [Arduino Mega 2560 Rev3](https://docs.arduino.cc/hardware/mega-2560) development board. This work has parts that reference its hardware design and comply with the transitive nature of the CC-BY-SA agreement it adopts. "Arduino" is a trademark owned by Arduino Corporation.
* This work is a reference design for the ATmega2560-16AU microcontroller ([Lichuang Mall Product C22460](https://item.szlcsc.com/23186.html)), as an optimization of the reference design I originally provided.
* This work belongs to the [Long-Term Support Project Portfolio](https://oshwhub.com/%E6%98%9F%E9%B8%A2%E9%BB%9B/album/Long-Term-Support).

# Project Description

![Cover.png]
This work is the third development board based on ATmega 2560 designed by me. Compared with previous projects, this work has a friendly pin sorting and single-sided mounting layout while maintaining a small size.

### About the Cold Rice Project

Although the LiChuang Mall ATmega2560 chip reference design I provided in the past as an early work when I was just starting to learn circuit design has many defects, everyone still supported me with considerable enthusiasm, thank you very much. However, I cannot respond well to the questions that people often ask, because no matter how you patch, the foundation of the house will not change. Therefore, I decided to redesign an ATmega2560 development board and provide long-term support and maintenance for it to thank everyone for their recognition of me. ~~ In view of this shameless behavior of reheating old things to cheat popularity, this project is named Code Rice. ~~

### About BOM

**Please do not use the automatically generated BOM. **See the attachment for the actual BOM. This problem is caused by the difference between my development habits and the automatic BOM logic of LCEDA, and I don't want to change it (

### About the panel

The first test version of the top panel was successful! Since the interface of the development board is almost close to the load-bearing limit of this shape, the connection of some parts of the panel is relatively weak and may break under impact, but it does not affect the use. I left a relatively large margin in the female header slot. If I am confident in my assembly precision, I can slightly reduce it to increase the mechanical strength. The bottom panel is still under design adjustment, but since it does not involve slotting and only pattern design, you can play freely!

See the attachment for specific design drawings!

## Connectivity and function

* Just plug in the USB cable, or provide 5.0V power supply through any 5V pin to meet all working conditions of the microcontroller (if it is too high or too low, the development board may not work or even be damaged);
* Full IO lead-out: 70 IOs arranged in an Arduino-compatible order and 16 other IOs;
* USB Type-C connector and onboard driver-free full-speed USB 2.0 to UART chip (CH343P) with customizable information, connected to UART 0;
* Onboard 1.25T-4P I2C interface connector (without pull-up resistor), arranged in a sequence compatible with all my other works;
* With a reset button, there are 4 LED indicators to display the status of power, UART0 Rx/Tx, and digital port 13 (ie PB7);
* Universal 2.54mm spacing ICSP burning port; the JTAG interface does not have a separate connector, and can be connected from the GPIO connector if necessary.

## PCB part design parameters and technical features

! [IMG_20230619_122507.jpg]
Previous versions have been abandoned, and the parameters are only for comparison reference.

| PCB version | Ver 1.00 | Ver 2.01 | **Ver 3.02** |
| --- | --- | --- | --- |
| PCB outer frame size | 50*50mm | 50***90**mm | 50*50mm |
| IO arrangement | Arrangement by register group is more difficult to use | Arrangement by user definition is easier to use | Arrangement by user definition is easier to use |
| Number of copper foil layers | 2 layers | 2 layers | 2 layers |
| Component mounting | Pin + double-sided mounting | Pin + single-sided mounting | Pin + single-sided mounting |
| Minimum design line width | 6 mil | 6 mil | 5 mil |
| Minimum design spacing | 6 mil | 6 mil | 5 mil | |
Minimum via outer diameter | 24 mil | 24 mil | 24 mil |
| Minimum via inner diameter | 12 mil | 12 mil | 12 mil |
| Minimum mounted component size | 0603 | 0603 | 0402 |
| Design software | EasyEDA Standard Edition | EasyEDA Standard Edition | EasyEDA Professional Edition |
| Mounting component package | System library | System library + Own library | System library + Own library |

The above parameters meet the process requirements of [Jialichuang](https://www.jlc.com/) for free proofing of double-layer boards. If you need to produce under other manufacturers or processes, please confirm the process parameter table provided by the manufacturer and make appropriate changes to the PCB design by yourself (if necessary).

### About soldering of SMD components

Yes, 0402 SMDs are indeed difficult to solder.

I really want to produce and sell them in small batches, but everyone has seen the increase in the price of ATmega2560 chips in recent years... and I dare not buy the cheap Taobao goods. So the estimated price may be around 88 yuan, which is meaningless.

## Configuring the development board

If you need to burn the Arduino-provided BootLoader for this development board to make it compatible with corresponding products, or if you need to customize the USB configuration for this development board, please refer to [Super detailed: How to burn the BootLoader for your Arduino and compatible boards](https://oshwhub.com/article/Write-Arduino-BL).

The following are some recommended reading materials.

* If you need to burn the Arduino BootLoader for the development board to make it compatible with corresponding products, please visit [Bootloader | Arduino Documentation | Arduino Documentation](https://docs.arduino.cc/hacking/software/Bootloader) or refer to relevant tutorials on the Internet.
* If you need to install a USB-to-serial port driver to improve the stability of the serial port chip and/or modify the customizable USB configuration, such as VID, PID, maximum current value, manufacturer and product information string, etc., please visit [USB-to-high-speed serial port chip CH343 - Nanjing Qinheng Microelectronics Co., Ltd.](https://www.wch.cn/products/ch343.html) to read the relevant methods and obtain the required computer software.

Note: The above external links are for reference only. I do not have the rights to the pages pointed to by the above links and the trademarks, articles, pictures or attachments therein. I am not responsible for the security of the website and the computer software provided.

## Updates and Fixes


| Version | Time | Description |
| --- | --- | --- |
| 3.00 | 2023-03-16 | Released the project. |
| 3.01 | 2023-04-09 | **-- Fix the problem that the serial port indicator is always on**. In contrast to CH340, CH343 outputs a high level in Tx by default and has a built-in pull-up resistor in Rx. Therefore, the development board ports D00 and D01 are normally high, causing the indicator to be always on. The indicator has been changed to light up at a low level. |
| 3.02 | 2023-05-23 |**-- Canceled the plate hole**. Although this design has little effect on manual soldering, considering various factors, the use of the plate hole is still avoided. **-- Add IIC pull-up resistor**. Add two resistors R9 and R10. If not needed, leave them blank. **-- Fixed the problem that the header display is different from the actual use**. |

## For archival reference only: Old model list

Please note that the following projects have abandoned support. I will **no longer** provide technical answers or hardware design modifications. There may be inappropriate descriptions of copyright information, etc., which are only kept for archival reference purposes.

* [Rev 1.0](https://oshwhub.com/Snowy_Iris/IC_ATMEGA2560)
* [Rev 2.1](https://oshwhub.com/Snowy_Iris/ICMega2560.Rev2)

# Contact the author

* Contact list [GitHub personal homepage](https://github.com/SnowyIris)
* QQ exchange group [★Cyber ​​Archaeology Society★](https://jq.qq.com/?_wv=1027&k=62Df1llt) (732574927)
* Open source hardware release [LiChuang Open Source Platform Personal Homepage](https://oshwhub.com/snowy_iris)
* Support and donation [Afdian Personal Homepage](https://afdian.net/a/Atranix)

Due to the characteristics of the platform, private messages and comments on the LiChuang Open Source Platform may not be replied or the reply interval may be very long. Please understand.

Looking for other development boards? Please refer to [**Miss Xing Yuandai's development board introduction**](https://oshwhub.com/article/ICMCU_board_series_guide)