The 51 microcontroller has a long development history since its inception and is one of the oldest and most widely used microcontrollers. To become an excellent microcontroller engineer, mastering the technology of the 51 microcontroller is essential. Today, we will discuss the minimum system of the 51 microcontroller, namely the 8051/8751 and 8031.
1. What is a Minimum System?
A system consisting of a microcontroller and the simplest external circuits that can maintain the operation of the microcontroller and perform some basic functional operations is called a minimum system.
2. 8051/8751 Hardware Minimum System
As shown in the figure, this diagram displays the hardware minimum system of the 8051/8751. For microcontrollers with on-chip ROM, they can constitute a minimum system by themselves.
The resources of this system are as follows:
① 4KB ROM, 256B RAM;
② Passive interrupt system;
③ Two 16-bit timer/counters;
④ One full-duplex serial UART;
⑤ Four parallel I/O ports.
3. 8031 Hardware Minimum System
The 8031 microcontroller has no on-chip ROM. To operate normally, it must be equipped with external ROM. The P3, P2, and P0 ports are all occupied, leaving only the P1 port for I/O use, while other functions remain unchanged.
However, it is important to note that the /EA pin of the 8031 must be grounded to access external memory. Since there is only one EPROM, the /OE can be grounded.
