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Post by ssnow on Dec 2, 2016 13:58:36 GMT
Hi all,
I've got a ShieldBuddy here which I'm experimenting with using the Arduino IDE and I can't seem to get the CAN transmit to work. I used the User Manual to create a simple sketch:
/*** Don't worry, the normal Arduino setup() and loop() are below this block! ***/
/* LMU uninitialised data */
StartOfUninitialised_LMURam_Variables
/* Put your LMU RAM fast access variables that have no initial values here e.g. uint32 LMU_var; */
EndOfUninitialised_LMURam_Variables
/* LMU uninitialised data */
StartOfInitialised_LMURam_Variables
/* Put your LMU RAM fast access variables that have an initial value here e.g. uint32 LMU_var_init = 1; */
EndOfInitialised_LMURam_Variables
/* If you do not care where variables end up, declare them here! */
uint8_t i;
/*** Core 0 ***/
void setup()
{
SerialASC.begin(115200);
SerialASC.println("Setting pins");
pinMode(LED_BUILTIN, OUTPUT);
SerialASC.println("Init CAN0");
CAN0_Init(500000);
SerialASC.println("Setup CAN msgs");
CAN0_TxInit(0x100, 0x7FFFFFFFUL, 8, 11, 0); // (msg ID, acceptance mask, DLC, 11 or 29 bit ID, msg object to use)
SerialASC.println("Booted");
}
void loop()
{
SerialASC.println(i++);
digitalWrite(LED_BUILTIN, !digitalRead(LED_BUILTIN));
CAN0_SendMessage(0x100, 0x12340000, 0x9abc0000, 8); // (msg ID, 32 bits low data, 32 bits high data, DLC)
delay(100);
}
/*** Core 1 ***/
/* CPU1 Uninitialised Data */
StartOfUninitialised_CPU1_Variables
/* Put your CPU1 fast access variables that have no initial values here e.g. uint32 CPU1_var; */
EndOfUninitialised_CPU1_Variables
void setup1()
{
}
void loop1()
{
}
/*** Core 2 ***/
/* CPU2 Uninitialised Data */
StartOfUninitialised_CPU2_Variables
/* Put your CPU2 fast access variables that have no initial values here e.g. uint32 CPU2_var; */
EndOfUninitialised_CPU2_Variables
/* CPU2 Initialised Data */
StartOfInitialised_CPU2_Variables
/* Put your CPU2 fast access variables that have an initial value here e.g. uint32 CPU2_var_init = 1; */
EndOfInitialised_CPU2_Variables
void setup2()
{
// put your setup code for core 2 here, to run once:
}
void loop2()
{
// put your main code for core 2 here, to run repeatedly:
}
My serial output is
Setting pins
Init CAN0
Setup CAN msgs
Booted
0
1
Which would indicate that the initialisation works fine, then the first time around loop (i = 0) the CAN send line is executed OK but the second time around (i = 1) the program hangs at the CAN send line. I don't see any messages on my CAN monitor.
What am I missing here? Is there a way to know if a message was transmitted successfully?
Cheers,
Stuart
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Post by mjb on Dec 2, 2016 14:33:45 GMT
Hi, If it is stuck in the CAN transmit function then it is caused by the CAN module being busy already.
A few things to check:
Is there another CAN node on the bus generating the ACK response? Have you got 120Ohm terminating resistors? A CAN test sketch is attached which sends messages from TC275 CAN0 to CAN1. iLLD_CAN.ino (5.15 KB) _
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ssnow
New Member
Posts: 3 
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Post by ssnow on Dec 5, 2016 10:49:15 GMT
Hi,
Checked my hardware and I'd miswired my transceiver slightly, however I believe I've found a bug in the CAN API - the CAN modules appear to get set to double the baud rate specified with CANn_Init();.
So if I write
CAN0_Init(500000);
that sketch in my first post will transmit at 1 Mbit/s. 250000 (as in the examples) produces 500 kbit and 125000 = 250 kbit. Can you replicate?
Cheers.
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Post by mjb on Dec 5, 2016 14:23:50 GMT
That's very strange. I will check!
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Post by mjb on Dec 5, 2016 15:17:58 GMT
OK, I can see why. The CAN module is being clock at double the expected rate. We will fix this in the next release.
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Post by mjb on Dec 6, 2016 11:11:08 GMT
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ssnow
New Member
Posts: 3
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Post by ssnow on Dec 7, 2016 11:57:48 GMT
Confirmed v1.19 has fixed the problem - tested at 100, 125, 250, 500, 800 and 1000 kbit.
Thanks!
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joao
New Member
Posts: 31
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Post by joao on Mar 7, 2017 8:44:46 GMT
Hello,
Does anyone have more examples of CAN codes?
I am being able to send messages using CAN0 but i am really struggling to receive them,
Thing how to get the message ID out from a received message, how to read the message,
The example provided is a starting point but its sending from CAN0 to CAN1 and it is a little confusing, at least for me.
thank you
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Post by Admin on Mar 7, 2017 9:26:07 GMT
The commonest reasons for the CAN transmit hanging up is that:
(i) There is no other device on the network generating an ACK response.
(ii) There are no 120Ohm terminating resistors on the network. This is critical for Baud rates > 100kBit/s
(iii) Baud rate too high for the physical layer design.
There are some other forum members who have used the CAN so hopefully one of them will chip in!
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Post by Admin on Mar 7, 2017 9:59:01 GMT
The CAN functions provided in the ShieldBuddy are simplified compared the underlying ones. The CANx_Receive() function has a prototype:
IfxMultican_Status CAN1_ReceiveMessage(uint32 CAN_Id, IfxMultican_Message *msg1, uint8 dlc)
The *msg parameter is a structure of type:
typedef struct
{
uint32 id; /**< \brief CAN message ID */
IfxMultican_DataLengthCode lengthCode; /**< \brief CAN message data length code */
uint32 data[2]; /**< \brief CAN message data */
boolean fastBitRate; /**< \brief CAN FD fast bit rate enable/disable */
} IfxMultican_Message;
Thus to get the received information:
ID = msg1.id;
DLC = msg1.lengthCode;
FirstPayloadByte = msg1.data[0] & 0x000000FF;
SecondPayloadByte = msg1.data[0] & 0x0000FF00;
ThirdPayloadByte = msg1.data[0] & 0x00FF0000;
FourthPayloadByte = msg1.data[1] & 0x000000FF;
And so on.
Note that the msg1.id will always be the value that was specified in the original function call:
RxStatus = CAN1_ReceiveMessage(0x100, &msg1, 8);
The RxStatus is an enum error report that has the meaning:
typedef enum
{
IfxMultican_Status_noError = 0x00000000,
IfxMultican_Status_notInitialised = 0x00000001,
IfxMultican_Status_wrongParam = 0x00000002,
IfxMultican_Status_wrongPin = 0x00000004,
IfxMultican_Status_busHeavy = 0x00000008,
IfxMultican_Status_busOff = 0x00000010,
IfxMultican_Status_notSentBusy = 0x00000020,
IfxMultican_Status_receiveEmpty = 0x00000040,
IfxMultican_Status_messageLost = 0x00000080,
IfxMultican_Status_newDataButOneLost = 0x00000100
} IfxMultican_Status;
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Post by sparrowdclxvi on Mar 7, 2017 10:02:16 GMT
What are you using to receive the CAN messages?
I always use a CAN bus reader, that way I can confirm the packets are being sent correctly.
I have some code I wrote in the Eclipse IDE, but I can't find the equivalent I had in the Arduino IDE. Would that help?
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joao
New Member
Posts: 31
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Post by joao on Mar 7, 2017 11:10:20 GMT
I am using a MCP2551 transciever connected to CAN0 RX and Tx.
i am only using CAN0 so i use:
CAN0_SendMessage(0x201, Lowdata, Highdata, 8); // to send messages
and
RxStatus = CAN0_ReceiveMessage(0x151, &msg1, 4); // ro recieve data
And i am being able to put the messages out, but when i recieve the RxStatus is always 0x40 so no message there...
I am using the Arduino IDE to program so the exal-mple here would be great, still i think that looking at the Eclipse IDe code can be of use.
TY
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joao
New Member
Posts: 31
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Post by joao on Mar 7, 2017 16:03:01 GMT
So this is the code i am using to receive the CAN communication:
void setup() {
// put your setup code for core 0 here, to run once:
SerialASC.begin(250000);
CAN0_Init(250000);
/* Parameters CAN ID, Acceptance mask, data length, 11 or 29 bit ID, Message object to use */
CAN0_TxInit(0x100, 0x7FFFFFFFUL, 8, 29, 0);
CAN0_RxInit(0x100, 0x7FFFF000UL, 8, 29, 1);
SerialASC.print("Multican is Initialized\n\r");
}
void loop() {
IfxMultican_Message msg1;
IfxMultican_Status RxStatus;
RxStatus = CAN0_ReceiveMessage(0x151, &msg1, 8); // Original
if (RxStatus != IfxMultican_Status_noError){
SerialASC.print("ERROR: single IfxMultican_Can_MsgObj_read Message returned ");SerialASC.print(RxStatus,HEX); SerialASC.print("\n\r");
}
SerialASC.print("Multican Basic data transactions are finished\n\r\n\r");
delay(500);
}
I want to recieve 8bytes in the ID 0x151 but RxStatus is returning 0x40 all the time.
Does anyone see any problem?
i am sending from an arduino Mega using mcp_can.h library, as told before i am being able to send from the shield buddy and read in the arduino but not in the opposite direction.
i am using a simple code to send the command in the arduino:
// demo: CAN-BUS Shield, send data
#include <mcp_can.h>
#include <SPI.h>
MCP_CAN CAN0(53); // Set CS to pin 10
void setup()
{
Serial.begin(250000);
// init can bus, baudrate: 500k
if(CAN0.begin(CAN_250KBPS) == CAN_OK) Serial.print("can init ok!!\r\n");
else Serial.print("Can init fail!!\r\n");
}
unsigned char stmp[8] = {0, 1, 2, 3, 4, 5, 6, 7};
void loop()
{
// send data: id = 0x00, standrad flame, data len = 8, stmp: data buf
CAN0.sendMsgBuf(0x151, 1, 8, stmp);
Serial.print("sent \r\n");
delay(1000);
}
Thaks for the help
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Post by Admin on Mar 7, 2017 16:10:12 GMT
Please try:
/* Parameters CAN ID, Acceptance mask, data length, 11 or 29 bit ID, Message object to use */
CAN0_RxInit(0x151, 0x7FFFFFFFUL, 8, 11, 1);
This matches the Arduino's transmissions, if the comments are correct!
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joao
New Member
Posts: 31
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Post by joao on Mar 7, 2017 16:25:20 GMT
Please try: /* Parameters CAN ID, Acceptance mask, data length, 11 or 29 bit ID, Message object to use */ CAN0_RxInit(0x151, 0x7FFFFFFFUL, 8, 11, 1); This matches the Arduino's transmissions, if the comments are correct! It did not worked, i am using 29bit IDs, the 1 in CAN0.sendMsgBuf(0x151, 1, 8, stmp); goes for 29bit, standart is 0 for 11 bits. |
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