Timo's NMEA2000 stm32 mcp2515

jsj · June 9, 2022, 2:09pm

Hi.
I’m trying to use Timo’s great NMEA2000 library on a STM32.
How do I specify which SPI port to use?
I also have a TFT connected, which needs max SPI-speed, but the CAN controller has a max of 10MHz, so I want to use two SPI-ports on my STM32.

Im using a Bluepill, but changed the STM to a STM32F103CBT6 (more memory).
I’m using Visual Studio Code with PlatformIO - a ST-LINK for upload/debug, a MCP2515 as controller and MCP2542 for transceiver.

Libraries (Timo’s):
N2kMsg.h
NMEA2000.h
mcp_can.h
NMEA2000_mcp.h
N2kMessages.h

The micro should have 2xSPI, but I can’t find info how to use SPI2
Just tell me if you need more information…

maxgerhardt · June 9, 2022, 2:30pm

I think library specific questions should go to Issues · ttlappalainen/NMEA2000 · GitHub.

I see that the library constructs this type of object which has a SetSPI function

github.com

ttlappalainen/NMEA2000_mcp/blob/master/NMEA2000_mcp.h#L138-L141


      
          public:
              tNMEA2000_mcp(unsigned char _N2k_CAN_CS_pin, unsigned char _N2k_CAN_clockset = MCP_16MHz,
                            unsigned char _N2k_CAN_int_pin = 0xff, uint16_t _rx_frame_buf_size=MCP_CAN_RX_BUFFER_SIZE);
              void SetSPI(SPIClass *_pSPI) { N2kCAN.setSPI(_pSPI); }

at this place

github.com

ttlappalainen/NMEA2000/blob/ad30dced133cf7063b97aaa9ea05e434912e9100/src/NMEA2000_CAN.h#L211


      
          #if !defined(USE_MCP_CAN_CLOCK_SET)
          #define USE_MCP_CAN_CLOCK_SET 16
          #endif
          
          
#if USE_MCP_CAN_CLOCK_SET == 8
          #define MCP_CAN_CLOCK_SET MCP_8MHz
          #else
          #define MCP_CAN_CLOCK_SET MCP_16MHz
          #endif
          
          
tNMEA2000 &NMEA2000=*(new tNMEA2000_mcp(N2k_SPI_CS_PIN,MCP_CAN_CLOCK_SET,N2k_CAN_INT_PIN,MCP_CAN_RX_BUFFER_SIZE));
          
          
#endif
          
          

          
#endif

So technically it might be possible to recast this pionter to its original type and call the SetSPI function on that…

#include <SPI.h>
//            MOSI  MISO  SCLK
SPIClass SPI_3(PC12, PC11, PC10);

void setup() {
  tNMEA2000_mcp* pNMEA = (tNMEA2000_mcp*) &NMEA2000;
  pNMEA->SetSPI(&SPI_3);
}

Creating a new SPI object is per API · stm32duino/wiki Wiki · GitHub.

(untested).

jsj · June 9, 2022, 3:42pm

Thanks - I’ll try in the weekend…I’m very new to C++ so I might get back with questions