Building a CAN API for Arduino DUE

haha2k:
Thank you Palliser and AddeD for the pointer and insight. I think I am truely confuse with the way this is set up. What I am going after at the moment is to just listen/spy on the bus for the traffic. Whether it be OBD2 or vehicle's internal bus I have been able to plug into it via an OBD2 shield in conjunction with UNO or simply a CAN232 without participating as a node and see data flow through. Yes, I am aware of how OBD2 work :slight_smile: on top of the request and respond the power train CAN in my vehicle contains hundreds of frames per seconds of other propriatary information aside from RPM, speed, temperature, etc. Again, thanks Palliaer I'll give it shot. The OBD2 is at 500 and I had tried them all. Here is another question, how come 100K isn't part of the constants list? Thanks,

If that's the case then I think what you want is to set one or more mailboxes to receive mode, not consumer mode. In consumer mode it sends a remote frame request on a certain ID and expects a reply back on that ID. I'm not sure how that'd work with OBDII. You merely need to set up a receive box and let traffic flow to it.

As for 100K, I'd guess it's not on the list because it just isn't that common. You should be able to add it though.

Hello jeancarlo19,

Here a procedure that should make the CAN sketches compile OK. I know the following is going to look drastic but it is the easiest way to do it.

Before proceed with the following steps, MAKE SURE to BACKUP your current Arduino 1.5.2 files.

Step 1: copy and replace ALL the folders/files from ...\Arduino-can\Arduino-can*.*
to ...\arduino-1.5.2-windows\arduino-1.5.2*.*

I want to clarify that ...\Arduino-can\Arduino-can\ refers to the CAN github stuff.
and ...\arduino-1.5.2-windows\arduino-1.5.2\ refers to your current arduino 1.5.2 stuff.

Step 2: Open the Arduino IDE 1.5.2

Step 3: Open any CAN sketch (now under ...\arduino-1.5.2-windows\arduino-1.5.2\hardware\arduino\sam\libraries\CAN).

Step 4: Import the CAN library (don't forget to set the Arduino Due (Programming Port) board)

And that's it. Now, you should be able to compile the sketch without errors/warnings.

The reason for the above procedure is because the CAN library was built as Arduino staging using in a prior Ardunio stuff.
Besides the CAN library itself, there are few files that have to be updated in the current 1.5.2 version. I will make time
to find and tell the only necessary files to copy/replace. Regards!

Attached to this post is the newest version of my copy of the canbus library. I've changed a lot but the examples are updated to reflect how it works now. It would be good to get feedback on whether this is a good direction to take the library or not. I'm not totally done with my modifications yet but it is in a usable state currently.

CAN.zip (24.8 KB)

Success!!! AdderD & Palliser thank you both again the priceless HINTS. After an hour of tweaking the code this evening I was able to tap into both the internal and OBD2 bus, the data flowed through into the serial monitor as if a flood gate was opened. Sorry TI for doubting the 3.3V compatibility to 5V (after the disappointment last night I ordered 10pcs of TJA1055/c thinking 3.3V is not what TI claimed to be). Next stop, double back to the consumer mode, set the ACK bit and make DUE as a node on the bus. It's exciting. Again without the inputs from both of you I would still be going in circles. The IRQ worked like charm, it's better than having to loop and loop to get the serial stream from CAN232 and miss 5-10% of the frames. I am SOLD!!!

Hello AdderD,

You are doing an amazing job. Thank you. I haven't get through all the improvements (just a glance) but looks/works very pretty now. Thank you also for adding a third sketch. This is how value is added here.

haha2k
I am happy you are on the move with the CAN library. Keep us posted about your progress.

I invite the CAN bus fans in the forum to join us and let us know how the library is working, picture of the CAN shield, etc. Regards!

Hi Palliser!

Thx for your help. Now it's working!!! I guess I had downloaded a wrong repository because I've already did without good results but I downloaded the repo again and now everything is compiling.

Gracias Pana!!

Here is another zip. I made a mistake in setting the ID for canbus frames and so basically all frames were being sent as ID 0. It works now. Whoops...

CAN.zip (24.9 KB)

Hi guys!

I've been trying out the CAN API and it works all right.

My sincere congrats to all developers. You have done an excellent work!

I have been testing the CAN api and everything works smooth at all speeds up to 1Mbps.

Although I have some comments:

The Can mailbox config structure "can_mb_conf_t" contains only two possible data, datah and datal. Is there any direct way to address individual bytes (B0 - B7) of the CAN message? Obviously the DLC param should has to be correctly set.

I'm using Line Driver SN65HVD232 (without any kind of low power mode, or anytingh else than pure CAN line driving) and I think that it is a little bit unconfortable to start up the transceiver as SSN65HVD234_Data can0_transceiver; instead of just using a generic CAN pin enable. Other options could also be using any 3V-5V line transceiver and using after any standard 5V Can driver.

Thank you again folks!

Lufe

lufegimenez:
Although I have some comments:

The Can mailbox config structure "can_mb_conf_t" contains only two possible data, datah and datal. Is there any direct way to address individual bytes (B0 - B7) of the CAN message? Obviously the DLC param should has to be correctly set.

You must not have downloaded the version I uploaded yesterday. In my new version there is an RX_CAN_FRAME structure which does expose all 8 data bytes.

I'm using Line Driver SN65HVD232 (without any kind of low power mode, or anytingh else than pure CAN line driving) and I think that it is a little bit unconfortable to start up the transceiver as SSN65HVD234_Data can0_transceiver; instead of just using a generic CAN pin enable. Other options could also be using any 3V-5V line transceiver and using after any standard 5V Can driver.

Yes, right now the code basically assumes you will be using a 234 chip. If you use my new version you might be able to set both Rs and En pins to be the same pin number. That would probably work alright for your use. Eventually we should support disabling the use of certain pins so that chips like 232 can be supported without wasting pins.

Just starting to try out!

Thanks!

Hi guys,

After being successful in the test between CAN bus 0 and 1 in Arduino Due, I've tried to receive messages from an ECU. This ECU sends 13 CAN frames of 64 bytes each one. I'm able to read the first frame but I have no idea about how to read the rest of them. By reading, I guess that the ECU is working with extended frame so I've been trying to mask the whole ID (CAN_ID and frame_ID), setting uc_id_ver=1 and some other options but nothing worked... Am I right with the extended frame CAN bus version? Has anybody experience on that? Is this library working with this kind of CAN bus?

Thanks!!

jeancarlo19:
After being successful in the test between CAN bus 0 and 1 in Arduino Due, I've tried to receive messages from an ECU. This ECU sends 13 CAN frames of 64 bytes each one.

Something is not right with this statement. You cannot send more than 8 bytes per frame. It is totally against the spec. This is not to mention that it is impossible to even set a DLC of more than 15 since it only uses 4 bits. So, you either mean 64 bits (8 bytes) or you mean that the ECU uses some form of higher level protocol to send messages as a series of frames. In the latter case there is no support for higher level protocols so that might be a problem.

I'm able to read the first frame but I have no idea about how to read the rest of them. By reading, I guess that the ECU is working with extended frame so I've been trying to mask the whole ID (CAN_ID and frame_ID), setting uc_id_ver=1 and some other options but nothing worked... Am I right with the extended frame CAN bus version? Has anybody experience on that? Is this library working with this kind of CAN bus?
Thanks!!

Yes, if you are using the official version of the library then uc_id_ver being set to 1 means extended frame. To tell you the truth, I have not tried the library (either the official one or the newer one I've worked on) with extended frames. It should work but I just haven't tested.

If you use my newer/modified version of the canbus library you will get hardware interrupts and a software buffer so you can just keep reading new frames out of the software buffer and not worry about messing with mailboxes. If you are using the official version then you need to check for whether a given mailbox has a new message and grab it if so. The act of grabbing the message clears the box to accept another message. So, that part is handled for you. Below are the relevant lines necessary to grab a message. If they're put in a loop you should be able to keep grabbing new messages as they come in.

  // Wait for CAN1 mailbox 0 to receive the data
  while (!(CAN.mailbox_get_status(CAN1, 0) & CAN_MSR_MRDY)) {
  }

  // Read the received data from CAN1 mailbox 0
  CAN.mailbox_read(CAN1, &can1_mailbox);

Of course, I'm going to suggest that you download the version of the library I posted a few messages back and use that. To me it's easier to work with. It will require quite a bit of changing your code around though since I changed so much. As luck would have it, I did update the examples so it should be pretty easy to get up to speed with the different way of doing things.

I will try to do some testing with extended frames to make sure that the library is working with them as well.

Hello chamo jeancarlo19,

please, confirm if your ECU is working with extended frames.

By default, all the CAN sample sketches work in the standard frame mode. For extended frames you will have to change the Mailbox ID register to CAN_MID_MIDvB instead of CAN_MID_MIDvA. This register CAN_MID_MIDvB needs to be SET for the mailbox to handle the extended format. Don't worry about the acceptance masking (MAM). The samples ORit depending on the format type.

In the same way as AdderD, I will be revising the extended format and try to bring an example using it. Regards!

Ok, I made a 4th example sketch in my copy of the canbus library. It turns out that extended frames do work fine already with the library. The sketch is a ping/pong type where the two canbus devices are set up to fire and receive frames pointing at each other so one sends, the other receives,then that one sends and the first receives, back and forth. Currently I have 100uS delay between each sending to slow things down a bit. I have tested this to be pretty stable. Right now I am looking at a serial monitor showing 5 million ping/pongs in a row. If I take the 100us delay out it will work VERY quickly but usually lock up after around 1 million ping/pongs. I don't know why quite yet, I assume the speed is causing it to sometimes miss setting things right and even one failed send will stop the sequence from happening.

Word to the wise, I test with a canbus to usb dongle also connected so I can see the traffic. I don't have a dongle that can handle 100,000 frames per second and you probably don't either. But, it appears the Due can do it. So, you kind of have to trust that the sent and received counters are accurate because it's hard to find another piece of hardware to verify.

I've attached the newest version of the library with the above 4th example.

Edit: I tested up to 100 million successful ping/pongs and quit. If it's stable to that much it seems stable enough. It would be good if someone wanted to try testing how little delay you can add and still have the traffic stay stable.

CAN.zip (26.5 KB)

Hi AllerD,

You're right... it's out of specs but frame format is 64 bytes and I'm supposed to received 13 frames of 64 bytes each one. In fact, by changing MAX_CAN_FRAME_DATA_LEN to 64 I'm received all bytes and reading the first frame. I guess ECU is using some higher level of protocol... I'll have to investigate. In any case, I'll download your library to test the extended version.

Hi Palliser,

I've already tested to change the Mailbox ID register to CAN_MID_MIDvB and everything worked the same way, I mean, I received the first frame as before but I don't know how to get the other 12 frames...

Whatever, I'll have to investigate further before continuing.

Thanks for your help!

perhaps the while loop at the very end of loop method? I sometimes overlook the simplest things and over complicate them (life of a code monkey!!!)

Hello friends

I've been programming for a while with the API and there are some questions that I don't get very well.

These are my questions for the gurus:

  1. I wasn't able to find the structure of "can_mb_conf_t" and the correspondence of the different elements with the CAN Register mapping (Section 41.9 of SAM3XA of Atmel documentation) so I get a little lost...
  2. I also would appreciate a list with all defined parameters.

Thats all by this time.

Thank you a lot!!!

Lufe

No problem Lufe,

typedef struct {
	uint32_t ul_mb_idx;
	uint8_t uc_obj_type;  //! Mailbox object type, one of the six different objects.
	uint8_t uc_id_ver;    //! 0 stands for standard frame, 1 stands for extended frame.
	uint8_t uc_length;    //! Received data length or transmitted data length.
	uint8_t uc_tx_prio;   //! Mailbox priority, no effect in receive mode.
	uint32_t ul_status;   //! Mailbox status register value.
	uint32_t ul_id_msk;   //! No effect in transmit mode.
	uint32_t ul_id;       //! Received frame ID or the frame ID to be transmitted.
	uint32_t ul_fid;      //! Family ID.
	uint32_t ul_datal;
	uint32_t ul_datah;
} can_mb_conf_t;

This can be found within the can.h file in the libsam files.

Here are some other relevant structures which are found in component_can.h in the CMSIS files:

typedef struct {
  RwReg  CAN_MMR;       // (CanMb Offset: 0x0) Mailbox Mode Register
  RwReg  CAN_MAM;       // (CanMb Offset: 0x4) Mailbox Acceptance Mask Register
  RwReg  CAN_MID;       /**< \brief (CanMb Offset: 0x8) Mailbox ID Register 
  RwReg  CAN_MFID;      /**< \brief (CanMb Offset: 0xC) Mailbox Family ID Register
  RwReg  CAN_MSR;       /**< \brief (CanMb Offset: 0x10) Mailbox Status Register 
  RwReg  CAN_MDL;       /**< \brief (CanMb Offset: 0x14) Mailbox Data Low Register 
  RwReg  CAN_MDH;       /**< \brief (CanMb Offset: 0x18) Mailbox Data High Register 
  RwReg  CAN_MCR;       /**< \brief (CanMb Offset: 0x1C) Mailbox Control Register 
} CanMb;
/** \brief Can hardware registers
#define CANMB_NUMBER 8
typedef struct {
  RwReg  CAN_MR;        /**< \brief (Can Offset: 0x0000) Mode Register 
  WoReg  CAN_IER;       /**< \brief (Can Offset: 0x0004) Interrupt Enable Register 
  WoReg  CAN_IDR;       /**< \brief (Can Offset: 0x0008) Interrupt Disable Register 
  RoReg  CAN_IMR;       /**< \brief (Can Offset: 0x000C) Interrupt Mask Register 
  RoReg  CAN_SR;        /**< \brief (Can Offset: 0x0010) Status Register 
  RwReg  CAN_BR;        /**< \brief (Can Offset: 0x0014) Baudrate Register 
  RoReg  CAN_TIM;       /**< \brief (Can Offset: 0x0018) Timer Register 
  RoReg  CAN_TIMESTP;   /**< \brief (Can Offset: 0x001C) Timestamp Register 
  RoReg  CAN_ECR;       /**< \brief (Can Offset: 0x0020) Error Counter Register 
  WoReg  CAN_TCR;       /**< \brief (Can Offset: 0x0024) Transfer Command Register 
  WoReg  CAN_ACR;       /**< \brief (Can Offset: 0x0028) Abort Command Register 
  RoReg  Reserved1[46];
  RwReg  CAN_WPMR;      /**< \brief (Can Offset: 0x00E4) Write Protect Mode Register 
  RoReg  CAN_WPSR;      /**< \brief (Can Offset: 0x00E8) Write Protect Status Register 
  RoReg  Reserved2[69];
  CanMb  CAN_MB[CANMB_NUMBER]; /**< \brief (Can Offset: 0x200) MB = 0 .. 7 
} Can;

If you look in the files I referenced you'll find a whole bunch of definitions. You can reference back and forth between those things and section 41 of the SAM3XA docs to figure things out.

However, the whole point of the canbus library is to make it so that you don't have to worry about all of these details. Palliser, I, and others have already been working on the library so that you don't have to worry about all these low-level details. My hope is that soon nobody will really wonder about can_mb_conf_t or any of the other low level structures. In my version of the lib I already basically removed all references and uses of that struct since it seems overly tied to hardware and complex to work with.

Thank you a lot!

I appreciate very much your work. I know how difficult it is to write libraries that match the needs of everybody. I will give a good use of this info!

I grow up in engineering through pages and pages of datasheets (when you had to get them in paper, long long time ago...) so although it is not the Arduino Spirit, sometimes I prefer go to a low level...

In any case THANK YOU!!!!! You guys have my full respect!

Lufe

Hello all, firstly may I please apologise if this appears to be a daft question, I am new to Arduino Can Bus on the Due.

I've had a look at the examples given and the library and the SAM manual section 41.7.2.1, but I'm at a loss to understand how to setup the Due to receive ALL messages regardless of id.

Or if it was setup to receive SAE J1939 messages (29 bit messages) that uses a 3 bit priority, then a 18 bit Parameter Group Number (PGN), and then an 8 bit source address for the message. The PGN allows for destination specific communication and broadcast communication. How to set it up to receive a range or all PGN messages or a bank of PGN messages.

Thanks for your time & advice in advance.

Rob