Swm32 series Tutorial 4 port mapping and serial port application

Let's introduce today SWM32 Port mapping of single chip microcomputer and application of serial port .

1. Port mapping

As mentioned in the previous article ,SWM32 The port mapping of Series MCU is relatively flexible . A peripheral can be mapped to many different GPIO, about PCB For wiring , A lot of convenience .

Can pass PORTx_SEL Register to configure which port a peripheral is mapped to . Here's the picture ：

With PC Take the mouth as an example ,PC0 You can configure the PORTC_SEL register , It maps to FUNMUX0 function ,PC1 It can be mapped to FUNMUX1 function , and FUNMUX0 and FUNMUX1 Functions can correspond to different peripherals . therefore PC0 and PC1 It can be flexibly configured for the functions of various digital peripherals .

But this is not infinitely flexible , Generally, the principle of odd and even distribution is followed , That is, even ports correspond to FUNMUX0 function , Odd ports correspond to FUNMUX1 function .

In actual programming , Directly call relevant functions , Take serial port as an example , To put UART0 Function mapping to PC2 and PC3 port , Call the following functions . The specific parameter description of the function can be seen in the comments .

PORT_Init(PORTC, PIN2, FUNMUX0_UART0_RXD, 1);       //GPIOC.2 Configure to UART0 Input pin 
PORT_Init(PORTC, PIN3, FUNMUX1_UART0_TXD, 0);       //GPIOC.3 Configure to UART0 Output pin 

2. Serial port application

A serial port （UART） Is one of the most commonly used interfaces in embedded . The design of the single chip microcomputer UART mouth , Has a depth of 8 Send and receive FIFO, Can reduce the CPU Frequency of interruption , Improve operational efficiency .

In general , We all use interrupt to send and receive data , Here also mainly introduces how to realize interrupt mode to send and receive data . Look directly at the program ：

void SerialInit(void)
{
       UART_InitStructure UART_initStruct;


       PORT_Init(PORTC, PIN2, FUNMUX0_UART0_RXD, 1);       //GPIOC.2 Configure to UART0 Input pin 
       PORT_Init(PORTC, PIN3, FUNMUX1_UART0_TXD, 0);       //GPIOC.3 Configure to UART0 Output pin 


        UART_initStruct.Baudrate = 115200;
       UART_initStruct.DataBits = UART_DATA_8BIT;
       UART_initStruct.Parity = UART_PARITY_NONE;
       UART_initStruct.StopBits = UART_STOP_1BIT;
       UART_initStruct.RXThreshold = 3;           // receive FIFO Threshold setting 
       UART_initStruct.RXThresholdIEn = 1;        // Enable receive interrupt 
       UART_initStruct.TXThreshold = 3;           // send out FIFO Threshold setting 
       UART_initStruct.TXThresholdIEn = 0;        // Send interrupt 
       UART_initStruct.TimeoutTime = 10;          //10 If no new data is received within a character time, a timeout interrupt is triggered 
       UART_initStruct.TimeoutIEn = 1;            // Enable timeout interrupt 
        UART_Init(UART0, &UART_initStruct);
       UART_Open(UART0);


       NVIC_EnableIRQ(UART0_IRQn);               // Open the serial port interrupt 
}

Baud rate and data bits 、 There is no need to say more about the setting of check bits , Mainly look at the settings of the interrupt part later .

Receive and timeout interrupts

First, you need to set reception FIFO threshold RXThreshold, meanwhile RXThresholdIEn=1 Enable receive interrupt . When receiving FIFO Number of data in >RXThreshold Receive interrupt occurs when . Unlike others without FIFO The single chip computer of , Receiving a byte generates an interrupt .

secondly , You also need to set the receiving timeout TimeoutTime, And enable timeout interrupt TimeoutIEn=1. When FIFO Data in the ≤RXThreshold when , And no new data is received after timeout , Timeout interrupt will occur . Two interrupts cooperate to complete the reading of a frame of data .

Sending and sending completion interrupt

Sending interrupt is similar to receiving interrupt , It also needs to be set FIFO threshold TXThreshold And enable interrupt TXThresholdIEn=1. It should be noted that there is no need to enable interrupt during initialization , Enable when you need to send data .

When the data is sent , You can then enable the send completion interrupt , The sending completion is interrupted at 485 It is very useful in half duplex applications .

Complete engineering reference ：

link ：https://pan.baidu.com/s/1KLbtE_FP1ZPY5UqlZwdY9Q?pwd=5ij6

Extraction code ：5ij6

Recommended reading ：

SWM32 Series of tutorials 1- Learn about the hardware

UART How high does baud rate require for clock accuracy ？

PCB Introduction to high current design method

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