A small mobile phone based on the Taishan School

PDF_CH340C Burner.zip

Altium_CH340C programmer.zip

PADS_CH340C programmer.zip

BOM_CH340C programmer.xlsx

93145

CW32 Voltage and Current Meter

Based on the CW32F030C8T6 geospatial voltage and current meter, this training camp taught me about CW32 development, ADC usage, and current sampling.

Participating in this training camp was beneficial because the strict rules required the use of development boards, so I had to obediently settle down and immerse myself in learning. This allowed me to fortunately discover the high precision and high configuration of the CW32 ADC. A powerful current and voltage meter can be implemented with just an MCU, without op-amps or current sensing devices like the INA226. Thanks to Engineer Li for the detailed and informative tutorials, and thanks to LCSC EDA for providing this excellent learning opportunity.
The learning content was quite extensive, so to avoid interference, I didn't make many changes; it was basically a direct copy of the instructor's work. To reduce the purchase of consumables, I made full use of the surface-mount components I had on hand. Resistors, capacitors, and LEDs were all replaced with surface-mount components, resulting in a smaller overall size. I made a mistake with the digital display; it's a bit too large. 
This current and voltage meter benefits from the CW32's 12-bit precision ADC, using a successive approximation method to measure relatively accurate voltage values. A 12-bit ADC means 2 to the power of 12, or 4096 voltage data levels. From 0 to 4096 corresponds to a range of 0 to 1.5V. The 1.5V is the MCU's internal reference voltage (an additional 2.5V reference voltage is also available, but lower voltages generally offer higher accuracy). For comparison, testing, and calibration, the board also provides a TL431 voltage reference chip, offering a 2.5V reference voltage with relatively high accuracy. Current measurement is also done by measuring the voltage and calculating the current value using a 100mΩ current sensing resistor. The 100mΩ current sensing resistor was
used for current measurement. I followed the teacher's Kelvin connection method; I'm not sure how effective it is. The accuracy is acceptable. It's very accurate even without calibration! I measured a dry cell battery at 1.601V with a good multimeter, and this voltmeter and ammeter gave roughly the same reading. 
Below is a picture of the actual device:
This training camp also encountered some difficulties, both in hardware and software. For example, I soldered the wrong voltage divider resistor, resulting in a 20-fold difference in the measured value. After a moment of confusion, I realized my mistake and immediately replaced the resistor to correct it. 
In terms of software, I also had a period where compilation failed. I only understood the problem after comparing several experimental examples. 
This training camp... Mr. Li, the instructor for CW32, provided meticulous explanations. Although the schematic diagram was a bit rough at first (there were a few discarded networks, I didn't know how to draw the 2mm banana plug, (A) in the diagram is an ammeter diagram, etc., which Mr. Li assumed everyone should know), after a few days of learning, I found that Mr. Li's video courses were full of valuable information. He even specially extracted common mistakes made by students and provided targeted explanations. I really learned a lot.
 
 

CW32 voltage and current meter.zip

QQ Video 20240813121010.mp4

PDF_CW32 Voltage and Current Meter.zip

Altium_CW32 voltage and current meter.zip

PADS_CW32 Voltage and Current Meter.zip

BOM_CW32 Voltage and Current Meter.xlsx

93146

Warm Winter Thermometer

The DS18B20 is a commonly used high-precision single-bus digital temperature measurement chip. It features small size, low hardware overhead, strong anti-interference capability, and high accuracy. Today, we will use the DS18B20 to design a lightweight electronic thermometer.

The DS18B20 is a commonly used high-precision single-bus digital temperature measurement chip. It features small size, low hardware overhead, strong anti-interference capability, and high accuracy.
Specifications: Temperature measurement range -55℃ to +125℃, with an error of ±0.4°C within the range of -10℃ to +85℃.
It returns a 16-bit binary temperature value
. Master-slave communication uses a single bus, meaning data transmission and reception are done via a single wire.
No external components are required; the chip itself can function independently.
The DS18B20 includes an internal EEPROM, and the digital conversion accuracy and alarm temperature can be set via configuration registers. Even after a power outage, it retains the resolution and alarm temperature settings.
Each DS18B20 has a unique 64-bit ID, allowing any number of DS18B20s to be connected to a single bus. The temperature value is read from the ROM by searching the DS18B20. The DS18B20 returns a 16-bit binary number representing the detected temperature, with the high five bits indicating whether it's positive
or
negative. If all five high bits are 1, the returned temperature is negative; if all five are 0, the returned temperature is positive. The following 11 bits represent the absolute temperature value. Converting this to decimal and multiplying by 0.0625 gives the current temperature value.
The DS18B20 has three pins:
GND: Power ground; DQ: Digital signal input/output; VDD: External power supply input. The operation of the DS18B20 can be divided into three steps:
1. Initialize the DS18B20; 2. Execute ROM instructions; 3. Execute DS18B20 function instructions
. The second step, executing ROM instructions, involves accessing each DS18B20, searching for its 64-bit serial number, reading the matching serial number value, and then matching it with the corresponding DS18B20. If we are only using a single DS18B20, we can skip the ROM instructions. The byte for skipping ROM instructions is 0xCC.
Here, we use a 74HC573, a 51 microcontroller minimum system, and a DS18B20.
The simulation is as follows: