各系列 CAN 功能差異

GD32系列MCU有關CAN外設各系列功能差異如下表GD32各系列MCU CAN外設功能差異表所示。

15.3.硬件連接說明

CAN 外設硬件連接圖

如圖CAN外設硬件連接圖所示，為典型的CAN外設硬件連接圖：SN65HVD230是收發器，其作用就是把CAN控制器的TTL電平轉換成差分信號。發送數據時，控制器把要發送的二進制編碼通過CAN_TX線發送到收發器，然后由收發器把這個邏輯電平轉換成差分信號，通過差分線CANH、CANL線輸出到總線網絡。當接收數據時，收發器把總線上收到的CANH、CANL信號轉換成邏輯電平，通過CAN_RX輸入到控制器。

讀者可以根據典型硬件連接圖和相應系列的Datasheet設計出自己的硬件連接方式。

15.4.軟件配置說明

本小節講解CAN_Example歷程中CAN模塊的配置說明，主要包括CAN外設配置、GPIO引腳配置、主函數介紹以及運行結果。本例程主要介紹GD32 MCU各系列CAN模塊的數據發送、接收，有關CAN其他功能例程可參考各系列固件庫歷程。

CAN 外設配置

外設配置如代碼清單CAN外設配置所示，在GD32全系列MCU中CAN外設的配置基本相同。GD32標準庫提供了CAN初始化結構體及初始化函數來配置CAN外設，其初始化結構體說明如下表CAN參數初始化結構體說明列表和CAN過濾器初始化結構體說明列表所示。需要注意的是本例程需要用到兩個開發板，一個發送，一個接收，這可以通過打開宏定義CAN_RECEIVE或CAN_TRANSMIT來決定當前是接收還是發送。

代碼清單 CAN 外設配置

void can_config(void) { #if defined (GD32F30X_CL) ||(GD32F4XX) ||(GD32F20X_CL)||(GD32F10X_HD) can_parameter_struct can_parameter; can_filter_parameter_struct can_filter_parameter; can_struct_para_init(CAN_INIT_STRUCT, &can_parameter); can_struct_para_init(CAN_FILTER_STRUCT, &can_filter_parameter); /* initialize CAN register */ can_deinit(CAN0); /* initialize CAN parameters */ can_parameter.time_triggered = DISABLE; can_parameter.auto_bus_off_recovery = DISABLE; can_parameter.auto_wake_up = DISABLE; can_parameter.no_auto_retrans = DISABLE; can_parameter.rec_fifo_overwrite = DISABLE; can_parameter.trans_fifo_order = DISABLE; can_parameter.working_mode = CAN_NORMAL_MODE; can_parameter.resync_jump_width = CAN_BT_SJW_1TQ; can_parameter.time_segment_1 = CAN_BT_BS1_5TQ; can_parameter.time_segment_2 = CAN_BT_BS2_4TQ; can_parameter.prescaler = 12; /* initialize CAN */ can_init(CAN0, &can_parameter); /* initialize filter */ can_filter_parameter.filter_number = 0; can_filter_parameter.filter_mode = CAN_FILTERMODE_MASK; can_filter_parameter.filter_bits = CAN_FILTERBITS_32BIT; can_filter_parameter.filter_list_high = 0x0000; can_filter_parameter.filter_list_low = 0x0000; can_filter_parameter.filter_mask_high = 0x0000; can_filter_parameter.filter_mask_low = 0x0000; can_filter_parameter.filter_fifo_number = CAN_FIFO0; can_filter_parameter.filter_enable = ENABLE; can_filter_init(&can_filter_parameter); #if defined (CAN_RECEIVE) #if defined (GD32F10X_HD) nvic_irq_enable(USBD_LP_CAN0_RX0_IRQn,0,0); #else nvic_irq_enable(CAN0_RX0_IRQn,0,0); #endif /* enable can receive FIFO0 not empty interrupt */ can_interrupt_enable(CAN0, CAN_INT_RFNE0); #endif #elif defined (GD32E10X) can_parameter_struct can_parameter; can_struct_para_init(CAN_INIT_STRUCT, &can_parameter); /* initialize CAN register */ can_deinit(CAN0); /* initialize CAN parameters */ can_parameter.time_triggered = DISABLE; can_parameter.auto_bus_off_recovery = DISABLE; can_parameter.auto_wake_up = DISABLE; can_parameter.auto_retrans = DISABLE; can_parameter.rec_fifo_overwrite = DISABLE; can_parameter.trans_fifo_order = DISABLE; can_parameter.working_mode = CAN_NORMAL_MODE; /* initialize CAN */ can_init(CAN0, &can_parameter); /* config CAN0 baud rate */ can_frequency_set(CAN0, DEV_CAN_BAUD_RATE); /* initialize filter */ can_filter_mask_mode_init(DEV_CAN_ID, DEV_CAN_MASK, CAN_EXTENDED_FIFO0, 0); #if defined (CAN_RECEIVE) /* configure CAN0 NVIC */ nvic_irq_enable(CAN0_RX0_IRQn, 0, 0); /* enable can receive FIFO0 not empty interrupt */ can_interrupt_enable(CAN0, CAN_INTEN_RFNEIE0); #endif #elif defined (GD32F1X0) can_parameter_struct can_parameter; can_filter_parameter_struct can_filter_parameter; /* initialize CAN register */ can_deinit(CAN1); /* initialize CAN parameters */ can_parameter.time_triggered = DISABLE; can_parameter.auto_bus_off_recovery = DISABLE; can_parameter.auto_wake_up = DISABLE; can_parameter.no_auto_retrans = DISABLE; can_parameter.rec_fifo_overwrite = DISABLE; can_parameter.trans_fifo_order = DISABLE; can_parameter.working_mode = CAN_NORMAL_MODE; can_parameter.resync_jump_width = CAN_BT_SJW_1TQ; can_parameter.time_segment_1 = CAN_BT_BS1_4TQ; can_parameter.time_segment_2 = CAN_BT_BS2_3TQ; can_parameter.prescaler = 18; /* initialize CAN */ can_init(CAN1, &can_parameter); /* initialize filter */ can_filter_parameter.filter_number = 15; can_filter_parameter.filter_mode = CAN_FILTERMODE_MASK; can_filter_parameter.filter_bits = CAN_FILTERBITS_32BIT; can_filter_parameter.filter_list_high = 0x0000; can_filter_parameter.filter_list_low = 0x0000; can_filter_parameter.filter_mask_high = 0x0000; can_filter_parameter.filter_mask_low = 0x0000; can_filter_parameter.filter_fifo_number = CAN_FIFO0; can_filter_parameter.filter_enable = ENABLE; can_filter_init(&can_filter_parameter); #if defined (CAN_RECEIVE) /* configure CAN1 NVIC */ nvic_irq_enable(CAN1_RX0_IRQn,0,0); can_interrupt_enable(CAN1, CAN_INTEN_RFNEIE0); #endif #endif }

CAN 參數初始化結構體說明列表

CAN 過濾器初始化結構體說明列表

GPIO 引腳配置

GPIO引腳配置如代碼清單CAN例程GPIO引腳配置所示。GD32F10X、GD32F30X、GD32F20X、GD32E10X系列用到remap功能，因此需要打開AF時鐘。使用GD32F1X0時，例程中是使用CAN1來進行收發。需要注意的是，發送時，不需要打開CAN0的時鐘，但是接收時需要打開CAN0的時鐘。

代碼清單 CAN 例程 GPIO 引腳配置

void can_gpio_config(void) { #if defined (GD32F4XX) /* enable CAN0 clock */ rcu_periph_clock_enable(RCU_CAN0); rcu_periph_clock_enable(RCU_GPIOB); /* configure CAN0 GPIO */ gpio_output_options_set(GPIOB, GPIO_OTYPE_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_8); gpio_mode_set(GPIOB, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO_PIN_8); gpio_af_set(GPIOB, GPIO_AF_9, GPIO_PIN_8); gpio_output_options_set(GPIOB, GPIO_OTYPE_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_9); gpio_mode_set(GPIOB, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO_PIN_9); gpio_af_set(GPIOB, GPIO_AF_9, GPIO_PIN_9); #elif defined (GD32E10X) || (GD32F30X_CL) ||(GD32F10X_HD) /* enable CAN0 clock */ rcu_periph_clock_enable(RCU_CAN0); rcu_periph_clock_enable(RCU_GPIOD); rcu_periph_clock_enable(RCU_AF); /* configure CAN0 GPIO */ gpio_init(GPIOD,GPIO_MODE_IPU,GPIO_OSPEED_50MHZ,GPIO_PIN_0); gpio_init(GPIOD,GPIO_MODE_AF_PP,GPIO_OSPEED_50MHZ,GPIO_PIN_1); #if defined (GD32F10X_HD) gpio_pin_remap_config(GPIO_CAN_FULL_REMAP,ENABLE); #else gpio_pin_remap_config(GPIO_CAN0_FULL_REMAP,ENABLE); #endif #elif defined (GD32F20X_CL) /* enable CAN0 clock */ rcu_periph_clock_enable(RCU_CAN0); rcu_periph_clock_enable(RCU_GPIOB); rcu_periph_clock_enable(RCU_AF); /* configure CAN0 GPIO */ gpio_init(GPIOB,GPIO_MODE_IPU,GPIO_OSPEED_50MHZ,GPIO_PIN_8); gpio_init(GPIOB,GPIO_MODE_AF_PP,GPIO_OSPEED_50MHZ,GPIO_PIN_9); gpio_pin_remap_config(GPIO_CAN0_PARTIAL_REMAP,ENABLE); #elif defined (GD32F1X0) //only GD32F170 and GD32F190 have CAN, GD32F130 and GD32F150 don't have /* enable CAN clock */ #if defined (CAN_RECEIVE) rcu_periph_clock_enable(RCU_CAN0); #endif rcu_periph_clock_enable(RCU_CAN1); rcu_periph_clock_enable(RCU_GPIOB); /* configure CAN1 GPIO */ gpio_output_options_set(GPIOB, GPIO_OTYPE_PP, GPIO_OSPEED_50MHZ,GPIO_PIN_12); gpio_mode_set(GPIOB, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO_PIN_12); gpio_af_set(GPIOB, GPIO_AF_9, GPIO_PIN_12); gpio_output_options_set(GPIOB, GPIO_OTYPE_PP, GPIO_OSPEED_50MHZ,GPIO_PIN_13); gpio_mode_set(GPIOB, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO_PIN_13); gpio_af_set(GPIOB, GPIO_AF_9, GPIO_PIN_13); #endif }

主函數配置

主函數配置如代碼清單主函數配置所示。本例程需要兩個開發板，一個作為發送，一個作為接收，這可以通過使用宏定義CAN_RECEIVE和CAN_TRANSMIT來實現。如果作為接收，那么主函數的開始會把can_receive_flag設置為RESET，并初始化LED2。LED2作為通訊的指示燈，如果通訊成功，就點亮LED2，否則就不點亮。can_receive_flag狀態的改變在中斷里實現，如果成功接收到數據，就會進入中斷，在中斷里把can_receive_flag設置為SET。主函數接下來對CAN的GPIO以及CAN模塊進行初始化。完成后，如果是作為發送方，程序需要設置需要發送的數據。有關發送結構體參數的說明，請見下表CAN發送消息初始化結構體說明列表。

代碼清單主函數配置

int main(void) { #if defined (CAN_RECEIVE) can_receive_flag = RESET; LED2_init(); #endif /* GPIO config */ can_gpio_config(); /* CAN config */ can_config(); #if defined (CAN_TRANSMIT) /* initialize transmit message */ #if defined (GD32E10X) || (GD32F30X_CL) || (GD32F10X_HD) || (GD32F4XX) || (GD32F20X_CL) can_struct_para_init(CAN_TX_MESSAGE_STRUCT, &g_transmit_message); #endif g_transmit_message.tx_sfid = 0x00; g_transmit_message.tx_efid = DEV_CAN_ID; g_transmit_message.tx_ft = CAN_FT_DATA; g_transmit_message.tx_ff = CAN_FF_EXTENDED; g_transmit_message.tx_dlen = 4; g_transmit_message.tx_data[0] = 0xaa; g_transmit_message.tx_data[1] = 0xbb; g_transmit_message.tx_data[2] = 0xcc; g_transmit_message.tx_data[3] = 0xdd; #if defined (GD32E10X) || (GD32F30X_CL) || (GD32F10X_HD) || (GD32F4XX) || (GD32F20X_CL) can_message_transmit(CAN0, &g_transmit_message); #elif defined (GD32F1X0) can_message_transmit(CAN1, &g_transmit_message); #endif #endif #if defined (CAN_RECEIVE) while(can_receive_flag == RESET); if((g_receive_message.rx_data[0] == 0xaa) && (g_receive_message.rx_data[1] == 0xbb)&& (g_receive_message.rx_data[2] == 0xcc) && (g_receive_message.rx_data[3] == 0xdd)) { LED2_ON(); } else { LED2_OFF(); } #endif while(1); }

CAN 發送消息初始化結構體說明列表

運行結果

本例程需要用到兩個開發板，用杜邦線把兩個開發板的CAN_H、CAN_L分別連接起來。打開CAN_Example例程，選擇好對應開發板的芯片工程后，先屏蔽掉CAN_RECEIVE，不屏蔽CAN_TRANSMIT ，編譯后把程序下載到一號開發板上。然后換一塊開發板，屏蔽掉CAN_TRANSMIT，不屏蔽CAN_RECEIVE，編譯后把程序下載到二號開發板上。接下來按下二號開發板的復位鍵，然后再按下一號開發板的復位鍵，此時會看到二號開發板的LED2被點亮，這表明通訊成功。

15.5.CAN 使用注意事項

（1） 使用F10X、F20X、F30X、F1X0、E10X、F403接收數據時如果出現接收兩幀數據會丟失一包的情況，這是由于手動多調用一次清緩存的操作導致的。因此，軟件中無需調用can_fifo_release函數；

（2） 使用F10X、F20X、F1X0時，會出現CAN離線后無法自動恢復，這是由于CAN模塊的離線自動恢復功能與CAN協議定義的離線恢復序列存在一定理解誤差造成的。該狀況可以通過使能離線中斷，在離線中斷內重新初始化CAN模塊來規避；

（3） GD32F170和GD32F190的CAN0內置PHY，其CANH和CANL口的耐壓范圍為VSS-0.3到VSS+7.5，內置的PHY不支持12V和24V系統。當使用CAN0時，建議硬件上按照下圖CAN0引腳連接圖連接。

CAN0 引腳連接圖