stm32f042 + can bus

[Josef Štengl]

Zkoušel jste přepnout CAN do loopback mode? Vyloučíte tím HW problémy jako například špatně zapájená nožička, chybně 
zapojený protikus, nezapojený terminační odpor (inu soudím dle sebe :-).

Mimochodem, pokud budete 1MBd provozovat na delší trase, a máte jiný protikus než ten samý čip, doporučoval bych (alespoň 
pro začátek) zvednou toleranci délky zprávy na 4 takty z 55 na 222 ns.

   CAN_InitStructure.CAN_SJW = CAN_SJW_4q;

Už jsem jednou narazil na to, že s malou tolerancí to při více zařízeních nepracovalo a CAN přecházel do error stavu. Po 
zvětšení tolerance to vykazovalo i žádanou činnost. Bylo to zrovna u STčka :-).

ced


Dne 10.11.2016 v 18:32 tomas mainzer napsal(a):
> dekuji zkusim, ale  zatim merim si primo na CANTX pinu, takze jakakoliv kolize na sbernici (za budicem) uz mi mereni
>  neovlivnuje. CANTX z procesoru se proste ani nehne;-)
>
> 2016-11-10 18:08 GMT+01:00 Jaroslav Buchta <jaroslav.buchta na hascomp.cz <mailto:jaroslav.buchta na hascomp.cz>>:
>
>     Zkuste CAN_ABOM a CAN_NART nastavit na ENABLE.
>     Neni sbernice defaultne v neklidovem stavu, treba prehozene H a L nebo zkrat? Radic to detekuje a po nejakych stech
>     cyklech se uvede do neprovozniho stavu (ABOM resi aspon automatickou reinicializaci po nejakem case klidu na sbernici)
>
>     Dne 10.11.2016 v 13:38 tomas mainzer napsal(a):
>>     Dobry den,
>>     nemate nekdo prosim funkcni priklad pro STM32F042 a can bus?
>>     Vychazim z prikladu pro STM32f072  - ake nedari se mi ani odeslat CAN packet - uz jsem vyzkousel priklady (puvodne
>>     pro STM32F072) pro SPL knihovny (to prekladam v embitz) i pro CubeMX (to prekladam v Atollic TRUEstudiu) a nedokazu
>>     prijit na to kde je zakopan pes.
>>     Uvitam jakekoliv tipy.
>>
>>     Nize je relevantni vysek programu pro SPL (CAN je na pinech PA11,PA12):
>>
>>
>>      GPIO_InitTypeDef  GPIO_InitStructure;
>>       NVIC_InitTypeDef  NVIC_InitStructure;
>>       CAN_InitTypeDef   CAN_InitStructure;
>>       CAN_FilterInitTypeDef  CAN_FilterInitStructure;
>>
>>
>>       /* CAN GPIOs configuration **************************************************/
>>
>>       /* Enable GPIO clock */
>>       //RCC_AHBPeriphClockCmd(CAN_GPIO_CLK, ENABLE);
>>       RCC_AHBPeriphClockCmd(RCC_APB1Periph_CAN, ENABLE);
>>       RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
>>
>>       /* Connect CAN pins to AF7 */
>>       GPIO_PinAFConfig(CAN_GPIO_PORT, CAN_RX_SOURCE, CAN_AF_PORT);
>>       GPIO_PinAFConfig(CAN_GPIO_PORT, CAN_TX_SOURCE, CAN_AF_PORT);
>>
>>       /* Configure CAN RX and TX pins */
>>       GPIO_InitStructure.GPIO_Pin = CAN_RX_PIN | CAN_TX_PIN;
>>       GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
>>       GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
>>       GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
>>       GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_UP;
>>       GPIO_Init(CAN_GPIO_PORT, &GPIO_InitStructure);
>>
>>       /* CAN NVIC  configuration **************************************************/
>>       NVIC_InitStructure.NVIC_IRQChannel = CEC_CAN_IRQn;
>>       NVIC_InitStructure.NVIC_IRQChannelPriority = 0;
>>       NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
>>       NVIC_Init(&NVIC_InitStructure);
>>
>>       /* CAN configuration ********************************************************/
>>       /* Enable CAN clock */
>>       RCC_APB1PeriphClockCmd(CAN_CLK, ENABLE);
>>
>>       /* CAN register init */
>>       CAN_DeInit(CANx);
>>       CAN_StructInit(&CAN_InitStructure);
>>
>>       /* CAN cell init */
>>       CAN_InitStructure.CAN_TTCM = DISABLE;
>>       CAN_InitStructure.CAN_ABOM = DISABLE;
>>       CAN_InitStructure.CAN_AWUM = DISABLE;
>>       CAN_InitStructure.CAN_NART = DISABLE;
>>       CAN_InitStructure.CAN_RFLM = DISABLE;//ENABLE;
>>       CAN_InitStructure.CAN_TXFP = DISABLE;//ENABLE;
>>       CAN_InitStructure.CAN_Mode = CAN_Mode_Normal;
>>       CAN_InitStructure.CAN_SJW = CAN_SJW_1tq;
>>
>>       /* CAN Baudrate = 1MBps (CAN clocked at 36 MHz) */
>>       CAN_InitStructure.CAN_BS1 = CAN_BS1_9tq;
>>       CAN_InitStructure.CAN_BS2 = CAN_BS2_8tq;
>>       CAN_InitStructure.CAN_Prescaler = 2;
>>       CAN_Init(CANx, &CAN_InitStructure);
>>
>>       /* CAN filter init "FIFO0" */
>>       CAN_FilterInitStructure.CAN_FilterNumber = 0;
>>       CAN_FilterInitStructure.CAN_FilterMode = CAN_FilterMode_IdList;
>>       CAN_FilterInitStructure.CAN_FilterScale = CAN_FilterScale_32bit;
>>       CAN_FilterInitStructure.CAN_FilterIdHigh = 0x6420;
>>       CAN_FilterInitStructure.CAN_FilterIdLow = 0x2461;
>>       CAN_FilterInitStructure.CAN_FilterMaskIdHigh = 0x0000;
>>       CAN_FilterInitStructure.CAN_FilterMaskIdLow = 0x0000;
>>       CAN_FilterInitStructure.CAN_FilterFIFOAssignment = 0;
>>       CAN_FilterInitStructure.CAN_FilterActivation = ENABLE;
>>       CAN_FilterInit(&CAN_FilterInitStructure);
>>
>>       /* Transmit Structure preparation */
>>       TxMessage.StdId = 0x321;
>>       TxMessage.ExtId = 0x00;
>>       TxMessage.RTR = CAN_RTR_DATA;
>>       TxMessage.IDE = CAN_ID_STD;
>>       TxMessage.DLC = 1;
>>
>>       /* Enable FIFO 0 full Interrupt */
>>       //CAN_ITConfig(CANx, CAN_IT_FF0, ENABLE);
>>       CAN_ITConfig(CANx, CAN_IT_FMP0, ENABLE);
>>
>>     ...
>>
>>     TxMessage.Data[0] = (uint8_t)(tick);
>>     CAN_Transmit(CANx, &TxMessage);
>>
>>
>>     Dekuji. TM.
>>
>>
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