DSP
在文章DSP_控制程序框架与优化-CSDN博客这篇文章中，我提到了用“高频小队列”的方式去处理与上位机的通信程序，最小的队列，就是一个节点只存储一个字节。用串口和上位机通信的方式是非常普遍的，本文讲描述一种串口通信的“高频小队列”框架。本框架其实核心的思想就是将串口的接收中断配置成1个字节就触发一次，中断处理程序只做一件事，就是把接收到的1个字节push到接收队列当中，然后在主程序 while(1)中去处理接收到的数据，对数据进行帧解析，为了让这个框架更普适，我们通过帧头和帧尾来截取一帧完整的数据，这样就能普适不定长的通信协议。 但帧解析的方式也很精细，我们是以10kHz的频率来处理，一次只处理一个字节，而不是直接一次把队列里面所有的数据都处理了。 同样的，我们要把数据通过串口发送给上位机，首先也是把需要发送的数据先一个字节一个字节的push到发送队列中，然后同样以10kHz的频率，一次只发送一帧出去，而不是一次性发完。
无论是接收数据、帧解析还是发送数据都是1字节1字节的处理，这样做的好处是，能够减少主程序对CPU时间片的需求。 进一步避免由于中断程序占用CPU时间片过长的问题。 如果中断占用CPU时间过长， 而主程序又是一次性处理很多数据（包括帧解析和发送），那么很有可能出现CPU一直被中断占用，而主程序又无法正常的执行的情况，最终呈现出来就是你上位机给DSP发信息，DSP直接无响应， DSP也无法发信息给上位机。
鲁棒的程序写法是，中断程序对CPU占用要尽量的减少，甚至一些不那么重要的但需要实时运行的程序比如ADC数据采集也可以放在while(1)之下，而不要全部放在中断程序中。 比如你ADC数据采集花了特别多的时间，导致中断处理程序的运行时间基本上快达到中断触发周期了，那留给其他中断和主程序的CPU时间片已经不多了，这就会导致程序异常，特别是主程序如果帧解析不是1个字节1个字节的解析的，发送数据也不是1个字节一个字节发送的。 这时候主程序的运行肯定就不正常了。
总得来说，中断程序一定是尽量的用时短而美，主程序while(1)里面的数据处理程序也是尽量的用时短而美，而不是一次性做很复杂的操作。
串口配置和单字节队列处理
/** scib.h**/#ifndef USERPROGRAM_PC_SCIB_H_
#define USERPROGRAM_PC_SCIB_H_
#include <main.h>
// Select the Baud rate of SCI
// #define _BAUD_9600_
// #define _BAUD_38400_
#define _BAUD_115200_
//#define _BAUD_256000_
//#define _BAUD_187500_
// #define _BAUD_460800_
//#define _BAUD_921600_void para_init(void);
void configScib(void);
void configScibGpio(void);
void configScibRegister(void);void ScibInterruptInit(void);#define MAX_RX_FRAME_SIZE 100extern Uint16 u_data_frame_array[MAX_RX_FRAME_SIZE];
extern Uint16 u_data_frame_length;
extern Uint16 is_data_frame_available;interrupt void getScib(void);
void sendScib(void);
void get_data_frame(void);#endif /* USERPROGRAM_PC_SCIB_H_ */
/** scib.c**/
#include <scib.h>// The communication port for display and control debugging is generally serial port
// SCI, Serial Communications Interfacevoid configScib(void)
{para_init();configScibGpio();configScibRegister();ScibInterruptInit();
}// Configure the multiplexing function of GPIO pin used by Scic
void configScibGpio(void)
{EALLOW;GpioCtrlRegs.GPAPUD.bit.GPIO18 = 0; // Enable pull-up for GPIO18 (SCITXDB)GpioCtrlRegs.GPAPUD.bit.GPIO19 = 0; // Enable pull-up for GPIO19 (SCIRXDB)GpioCtrlRegs.GPAQSEL2.bit.GPIO19 = 3; // Asynch input GPIO19 (SCIRXDB)GpioCtrlRegs.GPAMUX2.bit.GPIO18 = 2; // Configure GPIO18 for SCITXDB operationGpioCtrlRegs.GPAMUX2.bit.GPIO19 = 2; // Configure GPIO19 for SCIRXDB operationEDIS;
}// Configure relevant registers of Scic
void configScibRegister(void)
{/*---------------------------------------------SCICCR-------------------------------------------------------------*/// SCI number of stop bitsScibRegs.SCICCR.bit.STOPBITS = 0; // 0: One stop bit ▲// 1: Two stop bit// SCI parity odd/even selectionScibRegs.SCICCR.bit.PARITY = 0; // 0: Odd parity// 1: Even parity// SCI parity enableScibRegs.SCICCR.bit.PARITYENA = 0; // 0: Parity disabled ▲// 1: Parity is enabled// Loop Back test mode enableScibRegs.SCICCR.bit.LOOPBKENA = 0; // 0: Loop Back test mode disabled// 1: Loop Back test mode enabled// SCI multiprocessor mode control bitScibRegs.SCICCR.bit.ADDRIDLE_MODE = 0; // 0: Idle-line mode protocol selected// 1: Address-bit mode protocol selected// Character-length control bits 2-0ScibRegs.SCICCR.bit.SCICHAR = 7; // 0: SCICHAR_LENGTH_1 ▲// 1: SCICHAR_LENGTH_2// 7: SCICHAR_LENGTH_8/*---------------------------------------------SCICTL1--------------------------------------------------------------*/// SCI receive error interrupt enableScibRegs.SCICTL1.bit.RXERRINTENA = 0; // 0: Receive error interrupt disabled// 1: Receive error interrupt enabled// SCI software reset (active low)ScibRegs.SCICTL1.bit.SWRESET = 0; // 0: Writing a 0 to this bit initializes the SCI state machines// and operating flags (registers SCICTL2 and SCIRXST) to the reset condition.// 1: After a system reset, re-enable the SCI by writing a 1 to this bit.// SCI transmitter wake-up method selectScibRegs.SCICTL1.bit.TXWAKE = 0; // 0: Transmit feature is not selected. In idle-line mode: write// a 1 to TXWAKE, then write data to register SCITXBUF to generate// an idle period of 11 data bits / In address-bit mode: write a 1 to// TXWAKE, then write data to SCITXBUF to set the address bit for// that frame to 1// SCI sleep.ScibRegs.SCICTL1.bit.SLEEP = 0; // 0: Sleep mode disabled// 1: Sleep mode enabled// SCI Transmitter enableScibRegs.SCICTL1.bit.TXENA = 1; // 0: Transmitter disabled ▲// 1: Transmitter enabled// SCI receiver enableScibRegs.SCICTL1.bit.RXENA = 1; // 0: Prevent received characters from transfer into the ▲// SCIRXEMU and SCIRXBUF receiver buffers// 1: Send received characters to SCIRXEMU and SCIRXBUF/*---------------------------------------------SCICTL2------------------------------------------------------------*/ScibRegs.SCICTL2.bit.TXINTENA = 1; // SCITXBUF-register interrupt enable ▲ScibRegs.SCICTL2.bit.RXBKINTENA = 1; // Receiver-buffer/break interrupt enable ▲/*---------------------------------------------SCIHBAUD & SCILBAUD-------------------------------------------------*/// BRR = (SCIHBAUD << 8) + (SCILBAUD) = LSPCLK / (SCI Asynchronous Baud * 8) - 1#ifdef _BAUD_9600_ScibRegs.SCIHBAUD = 0x0001; // 9600 baud @ LSPCLK = 150/4 = 37.5MHz. ▲ScibRegs.SCILBAUD = 0x00E7; // 487.28d → 487d#endif#ifdef _BAUD_38400_ScibRegs.SCIHBAUD = 0x0000; // 38400 baud @ LSPCLK = 150/4 = 37.5MHz. ▲ScibRegs.SCILBAUD = 0x0079; // 121.07d → 121d#endif#ifdef _BAUD_115200_ScibRegs.SCIHBAUD = 0x0000; // 115200 baud @ LSPCLK = 150/4 = 37.5MHz. ▲ScibRegs.SCILBAUD = 0x0028; // 39.69d → 40d#endif#ifdef _BAUD_187500_ScibRegs.SCIHBAUD = 0x0000; // 115200 baud @ LSPCLK = 150/4 = 37.5MHz. ▲ScibRegs.SCILBAUD = 0x0018; // 39.69d → 40d#endif#ifdef _BAUD_256000_ScibRegs.SCIHBAUD = 0x0000; // 460800 baud @ LSPCLK = 150/4 = 37.5MHz. ▲ScibRegs.SCILBAUD = 0x0011; // 39.69d → 40d#endif#ifdef _BAUD_460800_ScibRegs.SCIHBAUD = 0x0000; // 460800 baud @ LSPCLK = 150/4 = 37.5MHz. ▲ScibRegs.SCILBAUD = 0x0009; // 39.69d → 40d#endif#ifdef _BAUD_921600_ScibRegs.SCIHBAUD = 0x0000; // 460800 baud @ LSPCLK = 150/4 = 37.5MHz. ▲ScibRegs.SCILBAUD = 0x0004; // 39.69d → 40d#endif// Relinquish SCI from Reset 【迷惑行为】ScibRegs.SCICTL1.all = 0x0023;/*---------------------------------------------SCIFFTX & SCIFFRX------------------------------------- ------------*/ScibRegs.SCIFFTX.bit.SCIRST = 1; // SCI ResetScibRegs.SCIFFTX.bit.SCIFFENA = 1; // SCI FIFO enableScibRegs.SCIFFTX.bit.TXFIFOXRESET = 1; // Transmit FIFO resetScibRegs.SCIFFTX.bit.TXFFST = 0; // FIFO status 0: Transmit FIFO is empty// 1: Transmit FIFO has 1 words// 10H: Transmit FIFO has 16 wordsScibRegs.SCIFFTX.bit.TXFFINTCLR = 0; // Transmit FIFO clearScibRegs.SCIFFTX.bit.TXFFIENA = 0; // Transmit FIFO interrrupt enableScibRegs.SCIFFTX.bit.TXFFIL = 9; // TXFFIL4-0 Transmit FIFO interrupt level bits.ScibRegs.SCIFFRX.bit.RXFFOVRCLR = 1; // RXFFOVF(Receive FIFO overflow) clearScibRegs.SCIFFRX.bit.RXFIFORESET = 1; // Receive FIFO resetScibRegs.SCIFFRX.bit.RXFFST = 6; // FIFO status 0: Receive FIFO is empty// 1: Receive FIFO has 1 words// 10H: Receive FIFO has 16 wordsScibRegs.SCIFFRX.bit.RXFFINTCLR = 1; // Receive FIFO interrupt clearScibRegs.SCIFFRX.bit.RXFFIENA = 1; // Receive FIFO interrupt enable// ScibRegs.SCIFFRX.bit.RXFFIL = 6; // Receive FIFO interrupt level bitsScibRegs.SCIFFRX.bit.RXFFIL = 1; // Receive FIFO interrupt level bits
}void ScibInterruptInit(void){// SCIBRXINT INT9.3// SCIBTXINT INT9.4// SCICRXINT InitialEALLOW;PieVectTable.SCIRXINTB = &getScib; // Specify the interrupt service routineEDIS;IER |= M_INT9; // Enable CPU Level interruptPieCtrlRegs.PIEIER9.bit.INTx3=1; // Enable PIE Level interrupt// SCICTXINT Initial// TODO
}// get one byte and push
interrupt void getScib(void)
{Uint16 data = ScibRegs.SCIRXBUF.all;enqueue(&scib_rx_queue, data);ScibRegs.SCIFFRX.bit.RXFIFORESET = 0;ScibRegs.SCIFFRX.bit.RXFIFORESET = 1;ScibRegs.SCIFFRX.bit.RXFFINTCLR = 1;PieCtrlRegs.PIEACK.all = PIEACK_GROUP9;
}// pop and send one byte
void sendScib(void)
{Uint16 data = 0;int ret = dequeue(&scib_tx_queue, &data);if(ret == 1){ScibRegs.SCITXBUF = data;while (ScibRegs.SCICTL2.bit.TXRDY == 0);}
}Uint16 last_data = 0;
Uint16 is_framehead_identified = 0;
Uint16 u_data_frame_effective_cnt = 0;
Uint16 u_data_frame_array[MAX_RX_FRAME_SIZE];
Uint16 is_data_frame_available = 0;
Uint16 u_data_frame_length = 0;void para_init(void)
{int i = 0;queue_init(&scib_rx_queue);queue_init(&scib_tx_queue);for(i = 0; i < MAX_RX_FRAME_SIZE; i++){u_data_frame_array[i] = 0;}
}// Indefinite length data frame acquisition
void get_data_frame(void)
{Uint16 data = 0;int ret = dequeue(&scib_rx_queue, &data);// The scib_rx_queue is not emptyif(ret == 1){// Frame head recognitionif(last_data==0x55 && data==0xAA){is_framehead_identified = 1;u_data_frame_array[0] = 0x55;u_data_frame_array[1] = 0xAA;u_data_frame_effective_cnt = 2;// Frame tail recognition}else if(is_framehead_identified==1 && last_data==0x66 && data==0x88){u_data_frame_array[u_data_frame_effective_cnt] = data;u_data_frame_length = u_data_frame_effective_cnt + 1;is_data_frame_available = 1;// save Frame data}else if(is_framehead_identified==1 && u_data_frame_effective_cnt < (MAX_RX_FRAME_SIZE-1)){u_data_frame_array[u_data_frame_effective_cnt] = data;u_data_frame_effective_cnt++;// frame length error}else if(is_framehead_identified==1 && u_data_frame_effective_cnt >= (MAX_RX_FRAME_SIZE-1)){last_data = 0;u_data_frame_effective_cnt = 0;is_framehead_identified = 0;}last_data = data;// The scib_rx_queue is empty}else{return;}
}/*
void sendScib(void)
{if(u_fr_tx_flag==1 && u_fr_tx_index < 16){ScibRegs.SCITXBUF = u_fr_tx_buf[u_fr_tx_index] & 0x00FF;u_fr_tx_index++;while (ScibRegs.SCICTL2.bit.TXRDY == 0);}else{u_fr_tx_flag = 0;u_fr_tx_index = 0;}}
*/
主程序和主中断
while(1){// 10kHzif(iFreq10000Hz == 1){get_adc(); // ADC如果耗时过多，可以放在主程序里，系统也能实现接近10kHz的性能// ADC如果耗时不多，放在主程序里，系统肯定是实现10kHz的性能// Pop and handle 【one byte】get_data_frame();// Execute PC Commandif(is_data_frame_available==1){fr_recv_decode();is_data_frame_available = 0;}// Pop and send 【one byte】sendScib();//runtime_stop(&runtime1);iFreq10000Hz = 0;}}// 用时最多的主中断（可能其他中断用0.几~几us，主中断用 < 50us的运行时间）
// 10kHz的话，相当于留50%的时间片给其他的中断和主程序
// 即使主程序运行一回要超过50us（但超过的不多哈），那整个系统基本上也是10kHz实时运行的。
interrupt void SystemMain(void)
{// do your main task// 用时短 而 美iFreq10000Hz = 1;PieCtrlRegs.PIEACK.all = PIEACK_GROUP1;}