hello,大家好。今天我又來啦,今天記錄一下S32K148-CAN裸機驅動編寫,有錯誤地方歡迎大家指正。
CAN的傳送接收在S32K148中主要有三種方式,一種是郵箱機制(mailbox),一種FIFO方式,還有一種DMA方式。郵箱方式較為簡單,也比較好理解。我的想法是先搞懂一種實現方式,再去慢慢研究其他方法。
郵箱機制主要涉及到一下暫存器:
還有一個RAMn[n]暫存器。
具體每個暫存器的功能資料手冊有詳細介紹,我就不逐個敘述了。直接根據我的demo程式來作簡要介紹。
CAN的初始化主要包括:
1)PCC時鐘使能
2)CAN傳送引腳和接收引腳的複用配置
3)CAN模組程式使能,同時進入凍結模式
4)配置時鐘,波特率,MB清0,接收MB的掩碼配置,接收MB的code配置
5)接收或傳送報文中斷使能
#define MSG_BUF_SIZE 4 /* Msg Buffer Size. (CAN 2.0AB: 2 hdr + 2 data= 4 words)1MB = 4words */ #define MB_FIFO_IDX_TX 16u /* MB for transmitting CAN message*/ #define MB_FIFO_IDX_RX 6u /* MB for transmitting CAN message*/ #define MB_FIFO_NUM 6u /* MB0~MB5 for FIFO engine*/
void can2_init(void) { PCC->PCCn[PCC_PORTB_INDEX] |= 1<<30; /*PIN MUX * PTB12 CAN2 RX * PTB13 CAN2 TX*/ PORTB->PCR[12] |= 1<<10; PORTB->PCR[13] |= 1<<10; /*CAN2 init*/ /*PCC FOR CAN2*/ PCC->PCCn[PCC_FlexCAN2_INDEX] |= 1<<30; /*CAN2 cfg*/ CAN2->MCR |= 1<<31; //mdis=1,disable module CAN2->CTRL1 &=~(1<<13); //CLKSRC=0,Clock Source = SOSCDIV2 CAN2->MCR &=~(1<<31); //mdis=0,ENable module //等待進入凍結模式 while( (CAN2->MCR & (1<<24))>>24 == 0 ); CAN2->CTRL1 = 0x01DB0006; //250k,rjw=11,psg1=011,psg2=011,propsg=110,clk=0,presdiv=1,配置時鐘and波特率 for(uint8_t i=24; i<128; i++ ) { /* CAN2: clear 32 msg bufs x 4 words/msg buf = 128 words */ CAN2->RAMn[i] = 0; /* Clear msg buf word */ } for(uint8_t i=0; i<32; i++ ) { /* In FRZ mode, init CAN2 16 msg buf filters */ CAN2->RXIMR[i] = 0xFFFFFFFF; /* Check all ID bits for incoming messages */ } CAN2->RXMGMASK = 0x00000000; /* Global acceptance mask: all ID bits DON'T CARE receive all ID message*/ CAN2->RAMn[ 0*MSG_BUF_SIZE + 0] = 0x04000000; /* Msg Buf 4, word 0: Enable for reception */ /* EDL,BRS,ESI=0: CANFD not used */ /* CODE=4: MB set to RX inactive */ /* IDE=0: Standard ID */ /* SRR, RTR, TIME STAMP = 0: not applicable */ //CAN2->RAMn[ 0*MSG_BUF_SIZE + 0] = 0x04200000; /* Msg Buf 4, word 0: Enable for reception */ /* EDL,BRS,ESI=0: CANFD not used */ /* CODE=4: MB set to RX inactive */ /* IDE=1: extend ID */ /* SRR, RTR, TIME STAMP = 0: not applicable */ CAN2->MCR = (0x0000001f) | (1<<17); /*SRXDIS=1,MAXMB=32*/ CAN2->MCR &= ~CAN_MCR_HALT_MASK; /* Negate HALT bit */ /*傳送和接收message中斷使能*/ CAN2->IMASK1 |= (1<<16)|(1<<0); /*bus off中斷使能*/ CAN2->CTRL1 |= (1<<15); while ((CAN2->MCR && CAN_MCR_FRZACK_MASK) >> CAN_MCR_FRZACK_SHIFT);/* Good practice: wait for FRZACK to clear (not in freeze mode) */ while ((CAN2->MCR && CAN_MCR_NOTRDY_MASK) >> CAN_MCR_NOTRDY_SHIFT);/* Good practice: wait for NOTRDY to clear (module ready) */ //註冊接收中斷向量 S32_NVIC_EnableIRQ(CAN2_ORed_0_15_MB_IRQn); S32_NVIC_EnableIRQ(CAN2_ORed_16_31_MB_IRQn); //註冊bus off中斷向量 S32_NVIC_EnableIRQ(CAN2_ORed_IRQn); }
CAN初始化過程中,需要注意地方在於接收掩碼如何配置(原則:0表示不關心,1表示關心),其次配置好接收MB的選擇同時使能相應MB的接收中斷。這裡面CAN傳送很簡單,主要針對CAN報文接收問題。
傳送函式,注意標準幀和擴充套件幀的設定
void can2_send_8Byte(uint8_t data[], uint8_t datalength, uint32_t id, uint8_t id_mode) { uint8_t i; uint8_t data_tem[datalength]; for(i=0;i<datalength;i++) { data_tem[i] = data[i]; } //CAN2->IFLAG1 |= 0xFFFF0000; //clear all transmit flag //wait bus idle // while( (CAN2->ESR1 & (1<<7))>>7 == 0 ); //data input CAN2->RAMn[MB_FIFO_IDX_TX*MSG_BUF_SIZE + 2] = data_tem[0]<<24 | data_tem[1]<<16 | data_tem[2]<<8 | data_tem[3]; CAN2->RAMn[MB_FIFO_IDX_TX*MSG_BUF_SIZE + 3] = data_tem[4]<<24 | data_tem[5]<<16 | data_tem[6]<<8 | data_tem[7]; //ID cfg if(id_mode == StandardID) { CAN2->RAMn[MB_FIFO_IDX_TX*MSG_BUF_SIZE + 1] = id<<18; CAN2->RAMn[MB_FIFO_IDX_TX*MSG_BUF_SIZE + 0] = 0x0C480000; //CODE=1100,SRR=1,IDE=0,RTR=0,DLC=1000 }else { CAN2->RAMn[MB_FIFO_IDX_TX*MSG_BUF_SIZE + 1] = id; CAN2->RAMn[MB_FIFO_IDX_TX*MSG_BUF_SIZE + 0] = 0x0C680000; //CODE=1100,SRR=1,IDE=1,RTR=0,DLC=1000 } }
接收函式
void can2_receive_8Byte(uint8_t id_mode) { can2_RecMessage.length = (CAN2->RAMn[0*MSG_BUF_SIZE + 0] >> 16) & 0xF; if(id_mode == StandardID) { can2_RecMessage.id = (CAN2->RAMn[0*MSG_BUF_SIZE + 1] >> 18) & 0x7FF; }else { can2_RecMessage.id = (CAN2->RAMn[0*MSG_BUF_SIZE + 1]) & 0x1FFFFFFF; } can2_RecMessage.data[0] = (CAN2->RAMn[0*MSG_BUF_SIZE + 2]) >> 24; can2_RecMessage.data[1] = ((CAN2->RAMn[0*MSG_BUF_SIZE + 2]) >> 16) & 0xFF; can2_RecMessage.data[2] = ((CAN2->RAMn[0*MSG_BUF_SIZE + 2]) >> 8) & 0xFF; can2_RecMessage.data[3] = (CAN2->RAMn[0*MSG_BUF_SIZE + 2]) & 0xFF; can2_RecMessage.data[4] = (CAN2->RAMn[0*MSG_BUF_SIZE + 3]) >> 24; can2_RecMessage.data[5] = ((CAN2->RAMn[0*MSG_BUF_SIZE + 3]) >> 16) & 0xFF; can2_RecMessage.data[6] = ((CAN2->RAMn[0*MSG_BUF_SIZE + 3]) >> 8) & 0xFF; can2_RecMessage.data[7] = (CAN2->RAMn[0*MSG_BUF_SIZE + 3]) & 0xFF; }
這個時候還不能接收,因為我需要把這個接收函式放到中斷函式中,因為我配置的接收MB為0,所以接收中斷函式是CAN2_ORed_0_15_MB_IRQHandler();
void CAN2_ORed_0_15_MB_IRQHandler(void) { gpio_reverse(PTe, 22); can2_receive_8Byte(StandardID); CAN2->IFLAG1 |= 0x0000FFFF;//清除標誌位 }
每次接收到報文後,進入中斷,在接收中斷函式裡讀取報文ID和DATA。注意在中斷函式裡清除相應的MB標誌位,即可進行下一次接收中斷。
本次我設定的接收全域性掩碼設定都為0x0,且設定的標準幀。所以對於所有的標準幀ID報文,我都可以接收。