Application of SPMC65P2408A in dual mic direction recognition

1 Introduction to the overall system solution

The hardware part is mainly used to amplify the sound. When the sound is loud enough, the signal can be introduced into the microcontroller for detection.
The software part is to complete the phase detection and time comparison to determine the direction of the sound.
The hardware composition block diagram 1-1 is shown. It is mainly composed of CPU, analog circuit and display circuit. The analog circuit is used for sound amplification, and the display LED board can display the current sound direction status.

Figure 1-1 Hardware block diagram

2 System Hardware Design

The hardware circuit is shown in Figure 2-1.
In the schematic diagram, it is divided into three parts. The left side is the mic recording circuit. The mic signal is blocked by a capacitor and reaches the middle amplifier circuit. The amplified signal reaches the right circuit and is output to the I/O port of the microcontroller after comparison.
The microcontroller part is not drawn in this schematic diagram.

Figure 2-1 System circuit schematic diagram

Figure 2-2 LED display circuit schematic

3. Introduction to Chip Features

SPMC2408A is an 8-bit industrial-grade microcontroller designed and developed by Lingyang Company. It uses SPMC65 CPU as the core and supports bit operation instructions. It has powerful timer/counter, rich external interrupt sources, ADC, PWM, standard communication interface and other functions. It is suitable for general industrial control occasions, computer peripheral control and home appliances. SPMC2408A has two packages: 28-pin and 32-pin. The 32-pin package has an additional UART function. This design uses the 28-pin package, as shown in Figure 3-1. [page]

Figure 3-1 SPMC2408A*28P

The specific features of the 28-pin packaged chip are as follows:
● 8-bit 6502 core of Lingyang Technology Company
● Operating voltage: 3.0V~5.5V
● Operating speed: 8MHz
● Operating temperature: -40℃~85℃
● Super strong anti-interference, anti-static ESD protection capability
● 8K byte ROM, 256 byte RAM
● 27 general input and output ports
● Powerful timer counter: 2 8-bit, 2 16-bit with Capture\\Compare\\PWM functions
● 1 1KHz~62.5KHz time base
● 8-channel 10-bit precision ADC (with external reference voltage)
● 4 external interrupts, 11 internal interrupts
● SPI serial communication interface
● 2 power saving modes: Halt, Stop
● Beeper output function
● Low voltage reset function
● Watchdog function

4 System Software Design

The main program flow is shown in Figure 4-1, and the interrupt flow is shown in Figure 4-2. The program is always checking whether there is a red or green LED display flag. If so, the corresponding LED will light up.

Figure 4-1 Main program flow chart

Figure 4-1 Interrupt flow chart

5 Conclusion

The SPMC65 series chips are suitable for various public control occasions with excellent performance and rich resources. The dual mic direction identification circuit developed with SPMC2408A as the main control chip only uses part of the resources of SPMC65P2408A, and there are still a lot of resources that can be used to complete the system control function.