1.前言:AUTOSAR通信系列介紹
這個(gè)系列是全新的系列,整個(gè)系列會(huì)通過(guò)實(shí)際操作,調(diào)試實(shí)際的代碼,以CAN為例,完整的解析AUTOSAR的從底層MCAL 到COM等上層模塊的通信鏈路層。重點(diǎn)講述數(shù)據(jù)的流向,以及各個(gè)模塊的作用,配置方法。
通過(guò)這個(gè)系列,將會(huì)以代碼的視角,了解如IPDU LPDU SDU HOH HTH HRH MB等AUTOSAR抽象概念的實(shí)際實(shí)現(xiàn)及其數(shù)據(jù)結(jié)構(gòu),以及在真實(shí)的AUTOSAR 架構(gòu)軟件中,CAN CANIF PDUR COM CANTP 等模塊中數(shù)據(jù)的傳輸,配置參數(shù),函數(shù)的調(diào)用等各個(gè)方面。讓我們?cè)谑褂肁UTOSAR配置通信的同時(shí),不被其架空,不當(dāng)只會(huì)配置的工具人。
系列將會(huì)從MCAL自底向上,一步步分析各個(gè)模塊,搞清楚整個(gè)通信的發(fā)送機(jī)制,和通信的接收機(jī)制。
2.Can_write函數(shù)介紹,以及HOH抽象的實(shí)施 MessgeBuffer介紹
整個(gè)的CAN發(fā)送,實(shí)際上是由Can模塊里面的Can_write實(shí)現(xiàn)的。我們先以S32K14x MCAL代碼為實(shí)例,介紹Can_write函數(shù)的發(fā)送機(jī)制,以對(duì)L_PDU HOH HTH Message Buffer這些抽象建立起基本的概念。
ECU執(zhí)行完必要的初始化函數(shù)和設(shè)置controller模式后,我們就可以調(diào)用Can_Write函數(shù)來(lái)發(fā)送報(bào)文了。
Can_Write函數(shù)的傳入?yún)?shù)有兩個(gè):
- hth:hardware transmit handle 硬件傳輸句柄。這個(gè)的詳細(xì)講解在后面。
- PduInfo(此即LPDU Data link Layer protocol)結(jié)構(gòu)體成員如下:
id:CAN報(bào)文ID
swPduHandle:LPDU 句柄,此句柄在Canif層定義。每個(gè)句柄表示的是1個(gè)LPDU.用來(lái)在發(fā)送的最后時(shí)刻觸發(fā)PDU的tx_confirmation.
length:LPDU數(shù)據(jù)長(zhǎng)度,即報(bào)文的長(zhǎng)度。
sdu:LPDU的數(shù)據(jù)指針。
實(shí)例:Can_write函數(shù)介紹,以及HOH抽象的實(shí)施 MessgeBuffer介紹
我們以一個(gè)簡(jiǎn)單的例子說(shuō)明:
如下是代碼:
如下是報(bào)文:
這個(gè)例子介紹了AUTOSAR發(fā)送報(bào)文的最底層接口的使用方法,可以先建立一個(gè)直觀的印象。
can_write的第一個(gè)參數(shù)hth是AUTOSAR標(biāo)準(zhǔn)里面的一個(gè)概念,接下來(lái)的內(nèi)容的講解目的是為了透徹的理解hth。
AUTOSAR從MCAL開(kāi)始 就對(duì)CAN進(jìn)行抽象了,抽象出HOH Hardware object handle 硬件處理對(duì)象,HOH以發(fā)送和接收的不同,分為了HTH,HRH,這倆可以統(tǒng)稱為HOH。
HOH對(duì)象包括很多屬性,如
Can Implementation Type(FULL/BASIC)
Can ID Message Type(STANDARD/MIXED/EXTEND)
Can Controller Reference (使用哪個(gè)can controler)
Number of Hw objects used to implement one HOH
等等屬性。
當(dāng)我們用其中的一個(gè)HOH作為對(duì)象來(lái)發(fā)送報(bào)文時(shí),這個(gè)報(bào)文的發(fā)送屬性會(huì)繼承這個(gè)HOH對(duì)象的所有屬性。
舉例說(shuō)明:
EB(S32K148)中配置了如下幾個(gè)HOH:
這里的配置實(shí)際會(huì)影響的是Can_PBcfg中的MessgeBuffer的配置結(jié)構(gòu)體,MessgeBuffer結(jié)構(gòu)體數(shù)組是HOH的具體實(shí)施,它的含義下文詳細(xì)描述。Can Object ID即為HOH的ID。
在Can_write例子中我們傳入HTH的是4,即利用HOH_3_EcuTestNode_CanCluster這個(gè)HOH作為對(duì)象,進(jìn)行發(fā)送。
深入Can_write中,調(diào)用的是Can_FlexCan_Write的這個(gè)函數(shù):
他會(huì)先搜索Messge Buffer配置結(jié)構(gòu)體中u32HWObjID為hth,即為4的這個(gè)配置。
Messge Buffer的配置結(jié)構(gòu)體的部分成員:
static CONST(Can_MBConfigObjectType, CAN_CONST) MessageBufferConfigs0_PB[CAN_MAXMBCOUNT_PB] =
{
/* HOH_0_EcuTestNode_CanCluster Message Buffer of Can Controller ID = 0U*/
{
(Can_HwHandleType)0x0U, /* uIdMaskIndex */
(uint8)0U, /* ControllerId - based on the order from CanController list */
(CanIdType)CAN_STANDARD, /* ID type: EXTENDED, STANDARD, MIXED */
(Can_ObjType)CAN_RECEIVE, /* Receive/Transmit MB configuration */
(Can_IdType)0x0U, /* MessageId */
(uint8)0x0U, /* Local priority bits used for arbitration */
(Can_HwHandleType)0x0U, /* Hardware Object ID */
#if (CAN_FD_MODE_ENABLE == STD_ON)
(uint8)0U,
#endif
/* Read/Write period reference used when POLLING mode is selected for the controller */
(uint8)0U, /* HOH configured for INTERRUPT mode, reference not used */
(uint16)0x0080U, /* Address of Message Buffer */
(uint8)8U, /* Payload lenth of Message Buffer */
(uint8)0U /* The index of MB in message buffer memory */
#if (CAN_TRIGGER_TRANSMIT_EN == STD_ON)
/* The parameter is used to detect the MB which run with trigger transmit feature */
,(boolean)FALSE
#endif
},
/* HOH_3_UDSTX_Node Message Buffer of Can Controller ID = 0U*/
{
(Can_HwHandleType)CAN_MAXMASKCOUNT, /* uIdMaskIndex */
(uint8)0U, /* ControllerId - based on the order from CanController list */
(CanIdType)CAN_STANDARD, /* ID type: EXTENDED, STANDARD, MIXED */
(Can_ObjType)CAN_TRANSMIT, /* Receive/Transmit MB configuration */
(Can_IdType)0x7eaU, /* MessageId */
(uint8)0x0U, /* Local priority bits used for arbitration */
(Can_HwHandleType)0x1U, /* Hardware Object ID */
#if (CAN_FD_MODE_ENABLE == STD_ON)
(uint8)0U,
#endif
/* Read/Write period reference used when POLLING mode is selected for the controller */
(uint8)0U, /* HOH configured for INTERRUPT mode, reference not used */
(uint16)0x0180U, /* Address of Message Buffer */
(uint8)8U, /* Payload lenth of Message Buffer */
(uint8)16U /* The index of MB in message buffer memory */
#if (CAN_TRIGGER_TRANSMIT_EN == STD_ON)
/* The parameter is used to detect the MB which run with trigger transmit feature */
,(uint8)FALSE
#endif
},
/* HOH_3_NMTX_Node Message Buffer of Can Controller ID = 0U*/
{
(Can_HwHandleType)CAN_MAXMASKCOUNT, /* uIdMaskIndex */
(uint8)0U, /* ControllerId - based on the order from CanController list */
(CanIdType)CAN_STANDARD, /* ID type: EXTENDED, STANDARD, MIXED */
(Can_ObjType)CAN_TRANSMIT, /* Receive/Transmit MB configuration */
(Can_IdType)0x424U, /* MessageId */
(uint8)0x0U, /* Local priority bits used for arbitration */
(Can_HwHandleType)0x2U, /* Hardware Object ID */
#if (CAN_FD_MODE_ENABLE == STD_ON)
(uint8)0U,
#endif
/* Read/Write period reference used when POLLING mode is selected for the controller */
(uint8)0U, /* HOH configured for INTERRUPT mode, reference not used */
(uint16)0x0190U, /* Address of Message Buffer */
(uint8)8U, /* Payload lenth of Message Buffer */
(uint8)17U /* The index of MB in message buffer memory */
#if (CAN_TRIGGER_TRANSMIT_EN == STD_ON)
/* The parameter is used to detect the MB which run with trigger transmit feature */
,(uint8)FALSE
#endif
},
/* HOH_3_XCPTX_Node Message Buffer of Can Controller ID = 0U*/
{
(Can_HwHandleType)CAN_MAXMASKCOUNT, /* uIdMaskIndex */
(uint8)0U, /* ControllerId - based on the order from CanController list */
(CanIdType)CAN_STANDARD, /* ID type: EXTENDED, STANDARD, MIXED */
(Can_ObjType)CAN_TRANSMIT, /* Receive/Transmit MB configuration */
(Can_IdType)0x667U, /* MessageId */
(uint8)0x0U, /* Local priority bits used for arbitration */
(Can_HwHandleType)0x3U, /* Hardware Object ID */
#if (CAN_FD_MODE_ENABLE == STD_ON)
(uint8)0U,
#endif
/* Read/Write period reference used when POLLING mode is selected for the controller */
(uint8)0U, /* HOH configured for INTERRUPT mode, reference not used */
(uint16)0x01a0U, /* Address of Message Buffer */
(uint8)8U, /* Payload lenth of Message Buffer */
(uint8)18U /* The index of MB in message buffer memory */
#if (CAN_TRIGGER_TRANSMIT_EN == STD_ON)
/* The parameter is used to detect the MB which run with trigger transmit feature */
,(uint8)FALSE
#endif
},
/* HOH_3_EcuTestNode_CanCluster Message Buffer of Can Controller ID = 0U*/
{
(Can_HwHandleType)CAN_MAXMASKCOUNT, /* uIdMaskIndex */
(uint8)0U, /* ControllerId - based on the order from CanController list */
(CanIdType)CAN_STANDARD, /* ID type: EXTENDED, STANDARD, MIXED */
(Can_ObjType)CAN_TRANSMIT, /* Receive/Transmit MB configuration */
(Can_IdType)0x110U, /* MessageId */
(uint8)0x0U, /* Local priority bits used for arbitration */
(Can_HwHandleType)0x4U, /* Hardware Object ID */
#if (CAN_FD_MODE_ENABLE == STD_ON)
(uint8)0U,
#endif
/* Read/Write period reference used when POLLING mode is selected for the controller */
(uint8)0U, /* HOH configured for INTERRUPT mode, reference not used */
(uint16)0x01b0U, /* Address of Message Buffer */
(uint8)8U, /* Payload lenth of Message Buffer */
(uint8)19U /* The index of MB in message buffer memory */
#if (CAN_TRIGGER_TRANSMIT_EN == STD_ON)
/* The parameter is used to detect the MB which run with trigger transmit feature */
,(uint8)FALSE
#endif
},
/* HOH_3_EcuTestNode_CanCluster Message Buffer of Can Controller ID = 0U*/
{
(Can_HwHandleType)CAN_MAXMASKCOUNT, /* uIdMaskIndex */
(uint8)0U, /* ControllerId - based on the order from CanController list */
(CanIdType)CAN_STANDARD, /* ID type: EXTENDED, STANDARD, MIXED */
(Can_ObjType)CAN_TRANSMIT, /* Receive/Transmit MB configuration */
(Can_IdType)0x110U, /* MessageId */
(uint8)0x0U, /* Local priority bits used for arbitration */
(Can_HwHandleType)0x4U, /* Hardware Object ID */
#if (CAN_FD_MODE_ENABLE == STD_ON)
(uint8)0U,
#endif
/* Read/Write period reference used when POLLING mode is selected for the controller */
(uint8)0U, /* HOH configured for INTERRUPT mode, reference not used */
(uint16)0x01c0U, /* Address of Message Buffer */
(uint8)8U, /* Payload lenth of Message Buffer */
(uint8)20U /* The index of MB in message buffer memory */
#if (CAN_TRIGGER_TRANSMIT_EN == STD_ON)
/* The parameter is used to detect the MB which run with trigger transmit feature */
,(uint8)FALSE
#endif
},........
所以上文函數(shù)搜索到的第一個(gè)結(jié)構(gòu)體成員一定是第一個(gè)Hardware Object ID為4的這個(gè)MB 結(jié)構(gòu)體:
/* HOH_3_EcuTestNode_CanCluster Message Buffer of Can Controller ID = 0U*/
{
(Can_HwHandleType)CAN_MAXMASKCOUNT, /* uIdMaskIndex */
(uint8)0U, /* ControllerId - based on the order from CanController list */
(CanIdType)CAN_STANDARD, /* ID type: EXTENDED, STANDARD, MIXED */
(Can_ObjType)CAN_TRANSMIT, /* Receive/Transmit MB configuration */
(Can_IdType)0x110U, /* MessageId */
(uint8)0x0U, /* Local priority bits used for arbitration */
(Can_HwHandleType)0x4U, /* Hardware Object ID */
#if (CAN_FD_MODE_ENABLE == STD_ON)
(uint8)0U,
#endif
/* Read/Write period reference used when POLLING mode is selected for the controller */
(uint8)0U, /* HOH configured for INTERRUPT mode, reference not used */
(uint16)0x01b0U, /* Address of Message Buffer */
(uint8)8U, /* Payload lenth of Message Buffer */
(uint8)19U /* The index of MB in message buffer memory */
#if (CAN_TRIGGER_TRANSMIT_EN == STD_ON)
/* The parameter is used to detect the MB which run with trigger transmit feature */
,(uint8)FALSE
#endif
},
以這個(gè)成員的配置去改變對(duì)應(yīng)的寄存器,從而讓發(fā)送的報(bào)文繼承這里面的屬性。
我們現(xiàn)在需要搞明白的就剩這個(gè)MessgeBuffer配置結(jié)構(gòu)體。
結(jié)構(gòu)體里面的屬性的含義,這些看EB的CAN模塊的配置手冊(cè)可以搞明白,我想介紹的是MessgeBuffer這個(gè)機(jī)制。這是S32K Flex CAN的機(jī)制
這是 Flex CAN的報(bào)文緩沖。報(bào)文緩沖有很多,配置好相關(guān)寄存器,最后將報(bào)文數(shù)據(jù)寫入報(bào)文緩沖,可完成發(fā)送。
我們注意到MessageBufferConfigs0_PB中的每個(gè)結(jié)構(gòu)體成員都有表示Address of Message Buffer的屬性和表示The index of MB in message buffer memory的屬性。這屬性各個(gè)成員全不同并且是序號(hào),地址按順序遞增的現(xiàn)象。所以這些結(jié)構(gòu)體成員就是一個(gè)一個(gè)不同的Messagebuffer。再注意到之前提到的Can_Write中傳入的Hth即是這里的Hardware Object ID。最后兩個(gè)結(jié)構(gòu)體,你發(fā)現(xiàn)他們雖然Message Buffer的地址不同,但是共用一個(gè)Hth號(hào)4.實(shí)際上完整的Messagebuffer的定義,有十個(gè)結(jié)構(gòu)體成員都是共用4號(hào)Hth.
這是由EB配置項(xiàng)Number of Hw objects used to implement one HOH配為10決定的。這里 Hw objects即不同的MessageBuffer。但是他們關(guān)聯(lián)了同個(gè)Hth。換言之1個(gè)Hth中可以包括多個(gè)MessageBuffer。即HTH是比MessageBuffer是更高層的抽象,例子中向Can_Write傳入這個(gè)ID為4的hth,可以有10個(gè)MessageBuffer供選擇寫入數(shù)據(jù),一個(gè)MessgeBuffer被占了我再找下個(gè)MessageBuffer。這樣的配置作用就是使用這個(gè)HTH,可以在極短時(shí)間同時(shí)支持最多10個(gè)報(bào)文的發(fā)送。
以上例子Can_write函數(shù)的底層實(shí)現(xiàn)的邏輯簡(jiǎn)化說(shuō)明如下:
1.輪詢Messge Buffer配置結(jié)構(gòu)體中u32HWObjID為hth是4的MB結(jié)構(gòu)體成員。
2找到第一個(gè)hth為4的MessageBuffer。傳入LPDU數(shù)據(jù),嘗試更新MessageBuffer發(fā)送,再判斷是否是CAN_BUSY狀態(tài)。假如是,找下一個(gè)Hth為4的MB繼續(xù)嘗試發(fā)送,直到成功發(fā)送出去一次,返回CAN_OK。
這期的介紹就到這里,本期我們可以搞清楚什么是LPDU,什么是HOH和HTH。從HOH的實(shí)際實(shí)施可以看出,所謂的AUTOSAR抽象,即將某個(gè)對(duì)象的所有配置,用結(jié)構(gòu)體數(shù)組打包在一起,然后給他們編號(hào)。這個(gè)編號(hào)和各個(gè)對(duì)象的配置一一對(duì)應(yīng)。后面需要使用這個(gè)對(duì)象的時(shí)候即使用編號(hào)去索引對(duì)應(yīng)的結(jié)構(gòu)體數(shù)組即可。這個(gè)思路會(huì)貫穿整個(gè)的AUTOSAR實(shí)現(xiàn)。
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