A digital oscilloscope Based on MCU

Introduction

We design a digital oscilloscope with STC8A8K chip as the control core, which mainly consists of two modules: hardware circuit and software program. The hardware module mainly includes OLED screen, voltage sampling circuit, clock system, power supply and management module and so on. The software module mainly includes A/D sampling, OLED display, interrupt timing and some necessary data processing. its measurable bandwidth is 0-3000Hz, the measured range is 0-30V. After many tests and comparisons, the design achieves the amplification and reduction of waveform and the measurement of different frequency waveform in the experimental process, so as to achieve the desired goal.

Methodology

Circuit block diagram

Hardware circuit module

The Hardware circuit is mainly divided into following parts and respective function are listed as follows：

Schematic diagram

A. Decoupling capacitors(a electrolytic capacitor 47uF & a ceramic capacitor 10nF):These two capacitors is at the power pin of microcontroller unit. The propose of this part is to keep the input voltage more stable and filter out the voltage spikes. So it can protect the microcontroller unit when the power on. They can also filter out the low and high frequency noise respectively.

B. Voltage divider circuit(a 1W 11k resistor & a 1/4w 2.2k resistor):

Experimental setup

Step 1:Preparation

Material List:

• MCU: STC8A8K64S4A12(core component)
• Display: SSD OLED with 7-Pin SPI Interface
• Resistor:1W 11k&1/4W 2.2k(for voltage division), 1/4W 11k(for current limiting) ,5k
• Capacitor:47uF, 0.01uF(for wave filtering)
• EC11 Encoder(for controlling of oscilloscope),Toggle Switch(for power switch),2-Pin Terminal(for input of oscilloscope),LED
• IC Socket 40-Pin,Row Pin(for installation of OLED display and programming the MCU)
• 3.7V Li-ion Battery(power source)
• 5V Booster Module(power module with Li-ion charging management and boost function)
• USB-TTL Downloader(for downloading program to MCU)
• Circuit Board