MB89163 single chip microcomputer and its application in remote control

MB89160/160A is a new 8-bit microcontroller series launched by Fujitsu of Japan. Because it adopts CMOS technology, high-density integrated process and modular structure, it has the characteristics of low power consumption, wide applicability and high cost performance. Therefore, it is particularly suitable for applications in remote control intelligent instruments and battery-powered equipment.
MB89163 is a model in the MB89160/160A series. It has two packages, QFE-80 and MQFP-80. It has 16K bytes of ROM and 512 bytes of RAM on the chip. The power supply voltage is 2.2V-6.0V, and the main clock and sub-clock are 4.194MHz and 32.768KHz respectively.
2. Internal structure and features
The internal functional block diagram of MB89163 is shown in Figure 1. As can be seen from the figure, the chip is a multi-functional microcontroller, which consists of LCD control/driver, A/D converter

Figure 1: Internal functional block diagram

The main features of MB89163 are as follows:
1. 8-bit, CMOS single-chip microcomputer; 2. Dual clock pulse control; 3. Modular structure; 4. High-density integrated process; 5. 54 programmable I/O lines; 6. The minimum execution time of instructions is 9.5μs (4.2MHz) and 400ns (10MHz) respectively; 7. Three power saving modes: sleep, monitor and stop mode; 8. 8-channel, 8-bit A/D converter; 9. 2-channel 8-bit PWM timer/controller; 10. Single-channel, 15-bit monitor prescaler; 11. Single-channel, 8-bit serial I/O port; 12. 12 external interrupts, 4 of which are edge-enabled and 8 are level interrupts; 13. The CPU is compatible with MB89600; 14. It has a remote control carrier frequency generator; 15. Built-in booster to drive LCD.
3. Hardware circuit and software analysis
The remote control receiving circuit composed of MB89163 and a few peripheral components is shown in Figure 2. This circuit is a remote control receiving circuit in communications and home appliances. It can be seen that the hardware circuit is very simple. The main clock and sub-clock both use external crystals, and their frequencies are 4.194MHz and 32.768KHz respectively. The external crystal is mainly used to improve the accuracy of the crystal frequency.

Figure 2: Remote control receiving circuit

The remote controller can use various data formats. Most of the "0" and "1" signals in them are composed of pulse width and high and low levels. The detailed data format is shown in Figure 3.

Figure 3: Remote control receiving data format

The basic functions of the remote control are timer and external interrupt. If the microcontroller receives a signal, an external interrupt is generated immediately, and then the pulse width type is determined by the timer. When the pulse width is consistent with the received signal, it is stored and the receiving cycle continues until the 12-bit data is received.
The program flow chart of the remote control receiver is shown in Figure 4. Now a brief description of the block diagram is given. Before the remote control receives, the system must be initialized, that is, the clock is selected, the stack pointer, interrupt layer, external interrupt 1, timer 1, time base timer, etc. are set, and the values ​​of various units such as L pulse, H pulse, input bit counter, frame cycle timer, and input data are cleared. After initialization, the above units meet the requirements before receiving.

Figure 4: Remote control receiver program flow chart

When the signal of the infrared remote control sensor is sent to P10/INT10 of the microcontroller, an external interrupt is generated. In the interrupt program, the main thing is to detect what type of pulse (H and L) is received. If the received signal is determined to be an L pulse, it is necessary to further determine whether it is the same as the guide pulse. If it is the same, the frame timer can be entered to complete the task of receiving 12 bits; if it is different, the quality of the H and L pulses must be evaluated. If the pulse quality is good, it is stored and the cyclic reception continues until the 12-bit data is received; if the pulse quality is not good, the cycle timer is stopped and the remote control condition is indicated to be invalid.