Design of General System Reset and Isolation Circuit for MSP430 Microcontroller

Single chip microcomputer STM32L151CCU6

Crystal patch 2520 2.5*2.0MM 12MHZ 12.000MHZ 1.6V~3.6V universal OSC

Typical applications of the MSP430 microcontroller include the acquisition of analog signals into digital signals for transmission to the host system for processing. We designed the general-purpose system of the MSP430 microcontroller and applied it to practical engineering to greatly shorten the development cycle and replace other microcontroller systems. Some of the experiences in the process of developing a universal board are now summarized to communicate with each other.

First, the design of the system reset circuit

The system reset circuit must be designed so that the system can be fully reset to work stably and reliably under various complicated conditions. The poor reset performance will affect the normal operation of the system. In the MSP430 microcontroller, there is a /RST reset pin and its non-maskable interrupt function. The pins are multiplexed and can be selected by software. The function is normally reset. As long as there is a low-level input system, it will be reset. Our reset circuit is designed based on this principle and guarantees a sufficient low-level time diagram. R33=68K R34=200 ohm C25 is 50 picofarads; We designed the actual circuit as shown and worked well.

Second, the design of the sampling isolation circuit

In order to stabilize the operation of the MSP430 MCU system and better remove the influence of external interference signals, we perform optocoupler isolation sampling on the input signal and boost the AC input signal so that the signal level is between 0VCC and suitable for MSP430x1xx series MCU. A/D sampling range, MSP430x1xx series MCU A/D sampling accuracy up to 12 bits, maximum sampling rate up to 200KBPS, sample/hold function ADC core controllable conversion memory and reference level generator, sampling clock Source and conversion timing circuit, optional We can use its internal reference level for A/D test reference level. From 0VCC, we can design the sampling protection and isolation circuit with TIL300 optocoupler, as follows for reference conditioning. The subsequent signal is connected to the A/D input terminal P60-P67. If there are more signals to be processed, the external expansion circuit can be connected.