CW32 Voltmeter and Ammeter Training Camp Project

Project Introduction: This project
describes a miniaturized (all-surface-mount design) integrated voltage and current meter based on the CW32 voltmeter and ammeter training program. We hope this successful experience will provide a unique perspective for enthusiasts.
1. The power supply circuit
uses a common 3.3V linear regulated power supply to power the chip and digital display.
2. Advantages of CW32

: Wide operating temperature range: -40~105℃;
Wide operating voltage: 1.65V~5.5V (STM32 only supports 3.3V systems)
; Strong anti-interference: HBM ESD 8KV; All ESD reliability reaches the highest international standard level (STM32 ESD 2KV)
; Project focus - Better ADC: 12-bit high-speed ADC, achieving ±1.0LSB INL 11.3ENOB; Multiple Vref reference voltages... (STM32 only supports VDD=Vref);
Stable and reliable eFLASH technology. (Flash0 pending)

3. The voltage sampling circuit
uses a voltage divider circuit to achieve high voltage acquisition. It is designed to acquire up to 100V, but the current configuration allows for acquisition of 0-30V.
4. The current sampling circuit
uses a low-side current sampling circuit for current detection. The low-side of the sampling circuit shares a common ground with the development board's meter interface .
5. The digital tube driver
uses a digital tube as the display unit.
6. Indicator lights:
An additional power indicator and an IO working indicator light are designed.
7. Button circuit.
8. TL431 circuit design for voltage measurement calibration:
An additional TL431 circuit is added to provide a 2.5V reference voltage, which can be used to provide an external voltage reference for calibrating the AD converter.
Voltage Testing:
1. 5V charger voltage test (error approximately 0.3V)
2. Battery voltage measurement test (error approximately 0.4V)