#The 7th Lichuang Electric Competition#USB voltage and current meter + TTL two-in-one

 
Pre: Let's take a look at the real thing first!
 
* 1. Project function introduction
 
I have a USB-TTL and a USB ammeter. These two look a bit similar. Let's combine them into one today!
 
 
* 2. Project attributes
 
This is the first time I participated in an electric competition. The voltage and current measurement part adopted the officially recommended solution, and then an additional USB serial port chip was added to achieve firmware burning without other tools.
 
 
* 3. Open source agreement
 
This project is open source under GPL3.0.
 
* 4. Hardware part
1. This time, the N32G430C8L7 provided by National Technology is used as the main control, CH340E is used as the USB to serial port chip, and the current sampling chip uses INA199A1DCKR.
2. Since it is planned to use the public mold shell provided by Taobao, the overall PCB is small. In order to facilitate the layout, XC6220B331MR-G is used as the 5V-3.3V LDO. The traditional 1117 package is too large, which will affect the layout.
3. The display part uses a 0.91-inch 4P I2C white OELD screen module.
4. I won’t say too much about the voltage, current and main control part design. I will directly refer to the official design plan. Here I will mainly talk about the USB serial port chip part. This project uses CH340E. 340E uses MSOP-10 package, which is very small and can meet the layout requirements.
Focus on R5 and R6. These two resistors are mainly used to connect CH340E and N32. After the firmware is burned, be sure to remove these two resistors, otherwise it will affect the normal operation of USB-TTL.
 
 
 
*5. Software part
1. The official firmware can be used directly for the software part. The official project address is: https://oshwhub.com/limengmeng12345/ji-chu-ying-usb-dian-ya-biao
2. Burning instructions:
      Since the USB serial port chip has been integrated, you only need to short the BOOT pad first and then power on when burning (you can also power on first, then short BOOT and keep it, and then short RST).
 
 
    The burning tool uses the official burning tool Nations MCU Download Tool V1.2.2 provided by National Technology, which is attached.
 
The burning tool is very simple to use. After short-circuiting BOOT as required and powering on, N32 will enter the download mode. Select "USART" in the tool interface, and
select the COM port corresponding to CH340 (right-click on my computer, manage--device manager--port, you can view it, the corresponding port on my computer is COM3),
then click Connect Device -> Browse (select the official firmware) -> Download.
 
*6. All BOM list
 
components are purchased from LiChuang Mall, and the specific specifications and models are in the list~~~
 
*7.
 
Finally, verify the competition LOGO~~~