Adc0832 and at89s52 interface circuit and vacuum data acquisition

Vacuum systems are extensively applied across various industries such as electric power, petrochemicals, medical and pharmaceutical sectors, plastics, environmental protection, and medical equipment. As the application of vacuum technology continues to expand and deepen, the demands on its performance are also increasing. For example, in diamond coating devices, where the deposition process can last for several tens of hours, the stability of the vacuum within the chamber significantly affects the quality of the deposited film. Therefore, maintaining a stable vacuum has become a critical technical challenge. In the vacuum pumping process involving centrifugal pumps, the vacuum level at the pumpâ€™s inlet serves as an essential parameter for determining start/stop operations and fault diagnosis. To achieve this, the analog signal from a pressure sensor must be effectively converted into a digital format through A/D conversion before being processed by the MCU and transmitted to a PC for waveform display and analysis. The author proposes using a combination of ADC0832 and a pressure sensor (PTB710), with the AT89S52 microcontroller managing the conversion process through clock pulse control. **1. A/D Conversion Circuit** **1.1 ADC0832 Chip Pin Description** Figure 1 shows the pin layout of the ADC0832. The CS pin is the chip select terminal, which is active low. CH0 and CH1 are the two analog input channels. DI is used for selecting the input channel, while DO is the serial output for the digital conversion result. CLK is the serial clock input, VCC (or REF) provides the positive supply and reference voltage, and GND is the ground connection.
**1.2 ADC0832 Working Control Principle** Table 1 outlines the multiplexed addressing modes of the ADC0832, including single-ended and differential multiplexing. Channel selection is controlled by the DI and DO pins. When the first bit is "1", only CH0 is selected for single-channel conversion. If the second bit is "1", then CH1 is selected. When both bits are "0", CH0 becomes the positive input (IN+), and CH1 becomes the negative input (IN-).
Table 1 ADC0832 Multiplexing Mode

**1.3 AT89S52 and A/D Interface Circuit** Figure 2 illustrates the interface circuit between the AT89S52 microcontroller and the ADC0832. The CS pin is connected to P2.3, and the CLK pin is connected to P2.2. Since the I/O ports of the MCU are bidirectional, and DI and DO are not active simultaneously during operation, they are connected in parallel and linked to P2.1 for data communication. The diagram includes the main MCU, power-on reset, crystal oscillator, and peripheral circuits for analog-to-digital conversion. Additional components include power supply, detection circuits, output ports, and logic conversion circuits. Considering industrial environments, optocouplers are added at the input and output to enhance noise immunity and system reliability.

Figure 2 ADC0832 and AT89S52 Interface Circuit
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