5. 硬件设计

查阅开发板手册，查询CAN相关外设的引脚信息，方便后续程序中配置GPIO。
本实验中我们使用CANA，也就是GPIO18,19。
image.png
image.png
image.png

6. 软件设计

  1. CAN初始化子函数
  2. CAN总线学习https://blog.csdn.net/qq_33693310/article/details/118492687

  3. include “DSP2833x_Device.h” // DSP2833x Headerfile Include File

include “DSP2833x_Examples.h” // DSP2833x Examples Include File

void InitECan(void)
{
//如果用到了CANA那么使能CANA，如果用到了CANB那么使能CANB
InitECana();
#if DSP28_ECANB
InitECanb();
#endif // if DSP28_ECANB
}

//CANA初始化函数
void InitECana(void)
{

struct ECAN_REGS ECanaShadow; //建立一个阴影寄存器，因为CAN的一些寄存器无法进行直接操作，需要一个阴影寄存器进行间接操作

  1. EALLOW;                                            // EALLOW enables access to protected bits
  4. ECanaShadow.CANTIOC.all = ECanaRegs.CANTIOC.all;//can的发送IO口的配置寄存器读出来，赋值给阴影寄存器<br />    ECanaShadow.CANTIOC.bit.TXFUNC = 1;                //将负责发送功能的阴影寄存器置一<br />    ECanaRegs.CANTIOC.all = ECanaShadow.CANTIOC.all;//将置一的阴影寄存器给can io寄存器赋值
  6. ECanaShadow.CANRIOC.all = ECanaRegs.CANRIOC.all;<br />    ECanaShadow.CANRIOC.bit.RXFUNC = 1;<br />    ECanaRegs.CANRIOC.all = ECanaShadow.CANRIOC.all;
  8. ECanaShadow.CANMC.all = ECanaRegs.CANMC.all;<br />    ECanaShadow.CANMC.bit.SCB = 1;                    //CANMC主控制器 SCB=1为选择eCAN模式，=0 在SCC模式下只有0-15号邮箱可以使用<br />    ECanaRegs.CANMC.all = ECanaShadow.CANMC.all;<br />    //清空邮箱的发送寄存器初始化<br />    ECanaMboxes.MBOX0.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX1.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX2.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX3.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX4.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX5.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX6.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX7.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX8.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX9.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX10.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX11.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX12.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX13.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX14.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX15.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX16.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX17.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX18.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX19.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX20.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX21.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX22.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX23.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX24.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX25.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX26.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX27.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX28.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX29.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX30.MSGCTRL.all = 0x00000000;<br />    ECanaMboxes.MBOX31.MSGCTRL.all = 0x00000000;<br />//==============================================================================

//清除所有的发送标志，发送标志
ECanaRegs.CANTA.all = 0xFFFFFFFF; / Clear all TAn bits ///发送应答寄存器
//清除所有的发送标志，接收标志
ECanaRegs.CANRMP.all = 0xFFFFFFFF; / Clear all RMPn bits ///接收消息挂起寄存器
ECanaRegs.CANGIF0.all = 0xFFFFFFFF; / Clear all interrupt flag bits ///全局中断标志寄存器
ECanaRegs.CANGIF1.all = 0xFFFFFFFF;

//==============================================================================
/ Configure bit timing parameters for eCANA/
ECanaShadow.CANMC.all = ECanaRegs.CANMC.all;
ECanaShadow.CANMC.bit.CCR = 1 ; // Set CCR = 1//CPU请求向配置寄存器CANBTC和SCC
//的接收屏蔽寄存器（CANGAM，LAM[0]，LAM[3]）写配置
//在该位置位后，CPU必须等到CANES寄存器的CCE标志位为1时，
//才能对CANBTC寄存器进行操作。如果ABO位置没有置位，CCR
//位将会在总线离线状态下置位，BO状态能够通过清除这一位而退出
//=1 请求对位时序进行配置

  1. ECanaRegs.CANMC.all = ECanaShadow.CANMC.all;<br />//=================================================================================<br />    ECanaShadow.CANES.all = ECanaRegs.CANES.all;<br />    do<br />    {<br />        ECanaShadow.CANES.all = ECanaRegs.CANES.all;<br />    } while(ECanaShadow.CANES.bit.CCE != 1 );          // Wait for CCE bit to be set..<br />    //CANES CCE=1 CPU已经对配置寄存器写访问 =0位拒绝<br />//=================================================================================<br />//波特率设置<br />    ECanaShadow.CANBTC.all = 0;
  3. #if (CPU_FRQ_150MHZ)                       // CPU_FRQ_150MHz is defined in DSP2833x_Examples.h<br />        /* The following block for all 150 MHz SYSCLKOUT (75 MHz CAN clock) - default. Bit rate = 1 Mbps<br />           See Note at End of File */<br />            ECanaShadow.CANBTC.bit.BRPREG = 4;<br />            //BRPREG为波特率预调节<br />            ECanaShadow.CANBTC.bit.TSEG2REG = 2;<br />            //时间段2位<br />            ECanaShadow.CANBTC.bit.TSEG1REG = 10;<br />            //时间段1位<br />    #endif<br />    #if (CPU_FRQ_100MHZ)                       // CPU_FRQ_100MHz is defined in DSP2833x_Examples.h<br />    /* The following block is only for 100 MHz SYSCLKOUT (50 MHz CAN clock). Bit rate = 1 Mbps<br />       See Note at End of File */<br />        ECanaShadow.CANBTC.bit.BRPREG = 4;<br />        ECanaShadow.CANBTC.bit.TSEG2REG = 1;<br />        ECanaShadow.CANBTC.bit.TSEG1REG = 6;<br />    #endif
  5. ECanaShadow.CANBTC.bit.SAM = 1;//设置CAN模块使用的采样数已决定CAN总线的实际水平。<br />                                    //=1 CAN模块采样三次，并以多数为准，三次采样只会在位速率预定值大于4时被选取。<br />                                    //=0 CAN模块只会在采样点采样一次<br />    ECanaRegs.CANBTC.all = ECanaShadow.CANBTC.all;<br />//========================================================================================<br />    ECanaShadow.CANMC.all = ECanaRegs.CANMC.all;<br />    ECanaShadow.CANMC.bit.CCR = 0 ;            // Set CCR = 0<br />                                                //=0 CPU请求正常操作。这只能在配置寄存器CANBTC置位位允许的值时完成。<br />    ECanaRegs.CANMC.all = ECanaShadow.CANMC.all;<br />//========================================================================================<br />    ECanaShadow.CANES.all = ECanaRegs.CANES.all;
  7. do<br />    {<br />       ECanaShadow.CANES.all = ECanaRegs.CANES.all;<br />    } while(ECanaShadow.CANES.bit.CCE != 0 );         // Wait for CCE bit to be  cleared..<br />    //CANES CCE=1 CPU已经对配置寄存器写访问 =0位拒绝

/ Disable all Mailboxes /
ECanaRegs.CANME.all = 0; // Required before writing the MSGIDs

  1. EDIS;<br />}

//CANB初始化函数 程序和初始化CANA是一样的。

//===========================================================================================
#if (DSP28_ECANB)
void InitECanb(void) // Initialize eCAN-B module
{
/ Create a shadow register structure for the CAN control registers. This is
needed, since only 32-bit access is allowed to these registers. 16-bit access
to these registers could potentially corrupt the register contents or return
false data. This is especially true while writing to/reading from a bit
(or group of bits) among bits 16 - 31 /

struct ECAN_REGS ECanbShadow;

EALLOW; // EALLOW enables access to protected bits

/ Configure eCAN RX and TX pins for CAN operation using eCAN regs/

  1. ECanbShadow.CANTIOC.all = ECanbRegs.CANTIOC.all;<br />    ECanbShadow.CANTIOC.bit.TXFUNC = 1;<br />    ECanbRegs.CANTIOC.all = ECanbShadow.CANTIOC.all;
  3. ECanbShadow.CANRIOC.all = ECanbRegs.CANRIOC.all;<br />    ECanbShadow.CANRIOC.bit.RXFUNC = 1;<br />    ECanbRegs.CANRIOC.all = ECanbShadow.CANRIOC.all;

/ Configure eCAN for HECC mode - (reqd to access mailboxes 16 thru 31) /

  1. ECanbShadow.CANMC.all = ECanbRegs.CANMC.all;<br />    ECanbShadow.CANMC.bit.SCB = 1;<br />    ECanbRegs.CANMC.all = ECanbShadow.CANMC.all;

/ Initialize all bits of ‘Master Control Field’ to zero /
// Some bits of MSGCTRL register come up in an unknown state. For proper operation,
// all bits (including reserved bits) of MSGCTRL must be initialized to zero

  1. ECanbMboxes.MBOX0.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX1.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX2.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX3.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX4.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX5.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX6.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX7.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX8.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX9.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX10.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX11.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX12.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX13.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX14.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX15.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX16.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX17.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX18.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX19.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX20.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX21.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX22.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX23.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX24.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX25.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX26.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX27.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX28.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX29.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX30.MSGCTRL.all = 0x00000000;<br />    ECanbMboxes.MBOX31.MSGCTRL.all = 0x00000000;

// TAn, RMPn, GIFn bits are all zero upon reset and are cleared again
// as a matter of precaution.

  1. ECanbRegs.CANTA.all    = 0xFFFFFFFF;    /* Clear all TAn bits */
  3. ECanbRegs.CANRMP.all = 0xFFFFFFFF;    /* Clear all RMPn bits */
  5. ECanbRegs.CANGIF0.all = 0xFFFFFFFF;    /* Clear all interrupt flag bits */<br />    ECanbRegs.CANGIF1.all = 0xFFFFFFFF;

/ Configure bit timing parameters for eCANB/

  1. ECanbShadow.CANMC.all = ECanbRegs.CANMC.all;<br />    ECanbShadow.CANMC.bit.CCR = 1 ;            // Set CCR = 1<br />    ECanbRegs.CANMC.all = ECanbShadow.CANMC.all;
  3. ECanbShadow.CANES.all = ECanbRegs.CANES.all;
  5. do<br />    {<br />        ECanbShadow.CANES.all = ECanbRegs.CANES.all;<br />    } while(ECanbShadow.CANES.bit.CCE != 1 );         // Wait for CCE bit to be  cleared..
  8. ECanbShadow.CANBTC.all = 0;
  10. #if (CPU_FRQ_150MHZ)                       // CPU_FRQ_150MHz is defined in DSP2833x_Examples.h<br />    /* The following block for all 150 MHz SYSCLKOUT (75 MHz CAN clock) - default. Bit rate = 1 Mbps<br />       See Note at end of file */<br />        ECanbShadow.CANBTC.bit.BRPREG = 4;<br />        ECanbShadow.CANBTC.bit.TSEG2REG = 2;<br />        ECanbShadow.CANBTC.bit.TSEG1REG = 10;<br />    #endif<br />    #if (CPU_FRQ_100MHZ)                       // CPU_FRQ_100MHz is defined in DSP2833x_Examples.h<br />    /* The following block is only for 100 MHz SYSCLKOUT (50 MHz CAN clock). Bit rate = 1 Mbps<br />       See Note at end of file */<br />        ECanbShadow.CANBTC.bit.BRPREG = 4;<br />        ECanbShadow.CANBTC.bit.TSEG2REG = 1;<br />        ECanbShadow.CANBTC.bit.TSEG1REG = 6;<br />    #endif
  12. ECanbShadow.CANBTC.bit.SAM = 1;<br />    ECanbRegs.CANBTC.all = ECanbShadow.CANBTC.all;
  14. ECanbShadow.CANMC.all = ECanbRegs.CANMC.all;<br />    ECanbShadow.CANMC.bit.CCR = 0 ;            // Set CCR = 0<br />    ECanbRegs.CANMC.all = ECanbShadow.CANMC.all;
  16. ECanbShadow.CANES.all = ECanbRegs.CANES.all;
  18. do<br />    {<br />        ECanbShadow.CANES.all = ECanbRegs.CANES.all;<br />    } while(ECanbShadow.CANES.bit.CCE != 0 );         // Wait for CCE bit to be  cleared..

/ Disable all Mailboxes /
ECanbRegs.CANME.all = 0; // Required before writing the MSGIDs

  1. EDIS;<br />}<br />#endif // if DSP28_ECANB

//===========================================================================================
//GPIO初始化程序 同样也是用到那个can初始化哪个
void InitECanGpio(void)
{
InitECanaGpio();
#if (DSP28_ECANB)
InitECanbGpio();
#endif // if DSP28_ECANB
}

//===========================================================================================
void InitECanaGpio(void)
{
EALLOW;

/ Enable internal pull-up for the selected CAN pins /
// Pull-ups can be enabled or disabled by the user.
// This will enable the pullups for the specified pins.
// Comment out other unwanted lines.

  1. GpioCtrlRegs.GPAPUD.bit.GPIO18 = 0;        // Enable pull-up for GPIO18 (CANRXA)
  3. GpioCtrlRegs.GPAPUD.bit.GPIO19 = 0;        // Enable pull-up for GPIO19 (CANTXA)

/ Set qualification for selected CAN pins to asynch only /
// Inputs are synchronized to SYSCLKOUT by default.
// This will select asynch (no qualification) for the selected pins.

GpioCtrlRegs.GPAQSEL2.bit.GPIO18 = 3; // Asynch qual for GPIO18 (CANRXA)

/ Configure eCAN-A pins using GPIO regs/
// This specifies which of the possible GPIO pins will be eCAN functional pins.

GpioCtrlRegs.GPAMUX2.bit.GPIO18 = 3; // Configure GPIO18 for CANRXA operation

GpioCtrlRegs.GPAMUX2.bit.GPIO19 = 3; // Configure GPIO19 for CANTXA operation

  1. EDIS;<br />}

if (DSP28_ECANB)
void InitECanbGpio(void)
{
EALLOW;

/ Enable internal pull-up for the selected CAN pins /
// Pull-ups can be enabled or disabled by the user.
// This will enable the pullups for the specified pins.
// Comment out other unwanted lines.

GpioCtrlRegs.GPAPUD.bit.GPIO16 = 0; // Enable pull-up for GPIO16 (CANTXB)

GpioCtrlRegs.GPAPUD.bit.GPIO17 = 0; // Enable pull-up for GPIO17 (CANRXB)

/ Set qualification for selected CAN pins to asynch only /
// Inputs are synchronized to SYSCLKOUT by default.
// This will select asynch (no qualification) for the selected pins.
// Comment out other unwanted lines.

GpioCtrlRegs.GPAQSEL2.bit.GPIO17 = 3; // Asynch qual for GPIO17 (CANRXB)

/ Configure eCAN-B pins using GPIO regs/
// This specifies which of the possible GPIO pins will be eCAN functional pins.

GpioCtrlRegs.GPAMUX2.bit.GPIO16 = 2; // Configure GPIO16 for CANTXB operation

GpioCtrlRegs.GPAMUX2.bit.GPIO17 = 2; // Configure GPIO17 for CANRXB operation

  1. EDIS;<br />}<br />#endif // if DSP28_ECANB