I modified the source code of MCP2515.ccp
(http://code.google.com/p/netduino-mcp2515/downloads/list)
to meet my project's requirement.
It support two CAN bus protocol chips and control by one SPI interface.
//-------------------------------------------------------------------------------------------
using System;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
namespace System
{
/// <summary>
/// Represents a class that handles the CAN transceiver MCP2515.
/// </summary>
public class MCP2515
{
//-------------------------------------
#region REGISTERS
//-------------------------------------
private const byte RXF0SIDH = 0x00;
private const byte RXF0SIDL = 0x01;
private const byte RXF0EID8 = 0x02;
private const byte RXF0EID0 = 0x03;
private const byte RXF1SIDH = 0x04;
private const byte RXF1SIDL = 0x05;
private const byte RXF1EID8 = 0x06;
private const byte RXF1EID0 = 0x07;
private const byte RXF2SIDH = 0x08;
private const byte RXF2SIDL = 0x09;
private const byte RXF2EID8 = 0x0A;
private const byte RXF2EID0 = 0x0B;
private const byte BFPCTRL = 0x0C;
private const byte TXRTSCTRL = 0x0D;
private const byte CANSTAT = 0x0E;
private const byte CANCTRL = 0x0F;
private const byte RXF3SIDH = 0x10;
private const byte RXF3SIDL = 0x11;
private const byte RXF3EID8 = 0x12;
private const byte RXF3EID0 = 0x13;
private const byte RXF4SIDH = 0x14;
private const byte RXF4SIDL = 0x15;
private const byte RXF4EID8 = 0x16;
private const byte RXF4EID0 = 0x17;
private const byte RXF5SIDH = 0x18;
private const byte RXF5SIDL = 0x19;
private const byte RXF5EID8 = 0x1A;
private const byte RXF5EID0 = 0x1B;
private const byte TEC = 0x1C;
private const byte REC = 0x1D;
private const byte RXM0SIDH = 0x20;
private const byte RXM0SIDL = 0x21;
private const byte RXM0EID8 = 0x22;
private const byte RXM0EID0 = 0x23;
private const byte RXM1SIDH = 0x24;
private const byte RXM1SIDL = 0x25;
private const byte RXM1EID8 = 0x26;
private const byte RXM1EID0 = 0x27;
private const byte CNF3 = 0x28;
private const byte CNF2 = 0x29;
private const byte CNF1 = 0x2A;
private const byte CANINTE = 0x2B;
private const byte MERRE = 7;
private const byte WAKIE = 6;
private const byte ERRIE = 5;
private const byte TX2IE = 4;
private const byte TX1IE = 3;
private const byte TX0IE = 2;
private const byte RX1IE = 1;
private const byte RX0IE = 0;
private const byte CANINTF = 0x2C;
private const byte MERRF = 7;
private const byte WAKIF = 6;
private const byte ERRIF = 5;
private const byte TX2IF = 4;
private const byte TX1IF = 3;
private const byte TX0IF = 2;
private const byte TX0IF_MASK = 0x04;
private const byte RX1IF = 1;
private const byte RX0IF = 0;
private const byte RX1IF_MASK = 0x02;
private const byte RX0IF_MASK = 0x01;
private const byte EFLG = 0x2D;
private const byte TXB0CTRL = 0x30;
private const byte TXREQ = 3;
private const byte TXB0SIDH = 0x31;
private const byte TXB0SIDL = 0x32;
private const byte EXIDE = 3;
private const byte EXIDE_MASK = 0x08;
private const byte TXB0EID8 = 0x33;
private const byte TXB0EID0 = 0x34;
private const byte TXB0DLC = 0x35;
private const byte TXRTR = 7;
private const byte TXB0D0 = 0x36;
private const byte RXB0CTRL = 0x60;
private const byte RXM1 = 6;
private const byte RXM0 = 5;
private const byte RXRTR = 3;
// Bits 2:0 FILHIT2:0
private const byte RXB0SIDH = 0x61;
private const byte RXB0SIDL = 0x62;
private const byte RXB0EID8 = 0x63;
private const byte RXB0EID0 = 0x64;
private const byte RXB0DLC = 0x65;
private const byte RXB0D0 = 0x66;
//-------------------------------------
#endregion REGISTERS
//-------------------------------------
//MCP2515 Command Bytes
private readonly byte RESET = 0xC0;
private readonly byte READ = 0x03;
// private readonly byte READ_RX_BUFFER = 0x90;
private readonly byte WRITE = 0x02;
// private readonly byte LOAD_TX_BUFFER = 0x40;
// private readonly byte RTS = 0x80;
// private readonly byte READ_STATUS = 0xA0;
// private readonly byte RX_STATUS = 0xB0;
private readonly byte BIT_MODIFY = 0x05;
/// <summary>Represent a LOW (false) state.</summary>
private const bool LOW = false;
/// <summary>Represent a HIGH (true) state.</summary>
private const bool HIGH = true;
/// <summary></summary>
private const byte DataIndexOffset = 2;
/// <summary>The max CAN ID that can be represented on an 11 bit ID.</summary>
private const int CANID_11BITS = 0x7FF;
//-------------------------------------------------------------
//// This must be modified for your CAN ID
private const uint VMS_CAN0_ID = 0x7E8, VMS_CAN1_ID = 0x329;
//-------------------------------------------------------------
// This must be modified depend on hardware
/// <summary>SPI PIN for VMS control.</summary>
public const Cpu.Pin SPI_CAN1_SEL = (Cpu.Pin)45; // PC13
public const Cpu.Pin SPI_CAN0_SEL = (Cpu.Pin)1; // PA1
/// <summary>the SPI object that communicate with the transceiver.</summary>
private SPI spi;
// Configure SPI CAN channel0 and channel1
private SPI.Configuration [] configSPI = new SPI.Configuration[2];
/// <summary>
/// Represents the available baud rates.
/// </summary>
public enum enBaudRate
{
CAN_BAUD_10K = 1, CAN_BAUD_50K = 2, CAN_BAUD_100K = 3,
CAN_BAUD_125K = 4, CAN_BAUD_250K = 5, CAN_BAUD_500K = 6
}
/// <summary>Represents a CAN message.</summary>
public class CANMSG
{
public uint CANID { get; set; }
public bool IsExtended { get { return CANID > CANID_11BITS; } }
public bool IsRemote { get; set; }
public int DataLength { get { return data.Length; } }
public byte[] data = new byte[8];
}
/// <summary>Initialize the CAN transceiver.</summary>
/// <param name="baudrate">The selected baud rate.</param>
/// <returns>True if configuration was successful.</returns>
/// <remarks>Transceiver needs to be set to normal mode before starting TX/RX operations.</remarks>
public bool InitCAN(enBaudRate baudrate)
{
configSPI[0] = new SPI.Configuration(SPI_CAN0_SEL, LOW, 0, 0, HIGH, HIGH, 10000, SPI.SPI_module.SPI1);
configSPI[1] = new SPI.Configuration(SPI_CAN1_SEL, LOW, 0, 0, HIGH, HIGH, 10000, SPI.SPI_module.SPI1);
spi = new SPI(configSPI[0]);
// Write reset to the CAN0/CAN1 transceiver.
spi.Write(new byte[] {RESET});
spi.Config = configSPI[1];
spi.Write(new byte[] {RESET});
//Read mode and make sure it is config
Thread.Sleep(100);
byte mode0 = (byte)(ReadRegister(0,CANSTAT) >> 5);
byte mode1 = (byte)(ReadRegister(1,CANSTAT) >> 5);
if ((mode0 != 0x04) || (mode1 != 0x04))
{
return false;
}
else // ------ Config mode -------------------
{
VMS_FilterInit();
SetCANBaud(baudrate); // will set to normal
SetCANNormalMode();
VMS_CAN0IdFilter();
//--------------- normal mode -----------------
return true;
}
}
/// <summary>Set the CAN baud rate.</summary>
/// <param name="baudrate">The configured baud rate.</param>
/// <returns>True if configured.</returns>
private bool SetCANBaud(enBaudRate baudrate)
{
byte brp;
//BRP<5:0> = 00h, so divisor (0+1)*2 for 125ns per quantum at 16MHz for 500K
//SJW<1:0> = 00h, Sync jump width = 1
switch (baudrate)
{
case enBaudRate.CAN_BAUD_10K:
brp = 5;
break;
case enBaudRate.CAN_BAUD_50K:
brp = 4;
break;
case enBaudRate.CAN_BAUD_100K:
brp = 3;
break;
case enBaudRate.CAN_BAUD_125K:
brp = 2;
break;
case enBaudRate.CAN_BAUD_250K:
brp = 1;
break;
case enBaudRate.CAN_BAUD_500K:
brp = 0;
break;
default:
return false;
}
byte[] cmdBuffer = new byte[] { WRITE, CNF1, (byte)(brp & 0x3F) };
spi.Config = configSPI[0];
spi.Write(cmdBuffer);
//-------------------------------------------------
//PRSEG<2:0> = 0x01, 2 time quantum for prop
//PHSEG<2:0> = 0x06, 7 time constants to PS1 sample
//SAM = 0, just 1 sampling
//BTLMODE = 1, PS2 determined by CNF3
spi.Write(new byte[] { WRITE, CNF2, 0xB1 });
//-----------------------------------------------
//PHSEG2<2:0> = 5 for 6 time constants after sample
//SOF enable <bit7>
spi.Write(new byte[] { WRITE, CNF3, 0x85 });
spi.Config = configSPI[1];
spi.Write(cmdBuffer);
spi.Write(new byte[] { WRITE, CNF2, 0xB1 });
spi.Write(new byte[] { WRITE, CNF3, 0x85 });
//SyncSeg + PropSeg + PS1 + PS2 = 1 + 2 + 7 + 6 = 16
return true;
}
/// <summary>Writes a value to the selected register.</summary>
/// <param name="registerAddress">The address of the register.</param>
/// <param name="value">The value to be write to the register.</param>
private void WriteRegister(uint channel ,byte registerAddress, byte value)
{
spi.Config = configSPI[channel];
spi.Write(new byte[] { WRITE, registerAddress, value});
}
/// <summary>Reads the value of the selected register.</summary>
/// <param name="registerAddress">The address of the register.</param>
/// <returns>A byte with the value read from the register.</returns>
private byte ReadRegister(uint channel,byte registerAddress)
{
byte[] CmdBuffer = new byte[] { READ, registerAddress };
byte[] outData = new byte[1];
spi.Config = configSPI[channel];
spi.WriteRead(CmdBuffer, outData, 2);
return outData[0];
}
/// <summary>Writes a bit to a register.</summary>
/// <param name="registerAddress">The address of the register that supports bit writing.</param>
/// <param name="bitNumber">The zero index based of the bit to write.</param>
/// <param name="value">the value of the bit to write.</param>
private void WriteRegisterBit(uint channel,byte registerAddress, byte bitNumber, byte value)
{
spi.Config = configSPI[channel];
//spi.Write(new byte[] { BIT_MODIFY, regno, (byte)(1 << bitno) });
if (value != 0)
{
spi.Write(new byte[] { BIT_MODIFY, registerAddress, (byte)(1 << bitNumber), 0xFF });
}
else
{
spi.Write(new byte[] { BIT_MODIFY, registerAddress, (byte)(1 << bitNumber), 0x00 });
}
}
/// <summary>Transmit a CAN message to the bus.</summary>
/// <param name="message">The CAN Message to be transmitted.</param>
/// <param name="timeout"></param>
/// <returns></returns>
public bool Transmit(uint channel ,CANMSG message, int timeout)
{
// Holds if message was sent or not.
bool sentMessage = false;
// Calculate the end time based on current device time.
TimeSpan startTime = Utility.GetMachineTime();
TimeSpan endTime = startTime.Add(new TimeSpan(0,0,0,0,timeout));
//--------------------------------------
// Set the CAN ID.
byte val = 0x00;
uint bit11Address = 0x00;
uint bit18Address = 0x00;
// Build Extended CAN ID
if (message.IsExtended)
{
// Split the 11 bit and 18 bit sections of the ID.
bit11Address = (uint)((message.CANID >> 16) & 0xFFFF);
bit18Address = (uint)(message.CANID & 0xFFFFF);
// Set the first part of the ID
val = (byte)(bit11Address >> 5);
WriteRegister(channel,TXB0SIDH, val);
// Set the second part of the ID.
val = (byte)(bit11Address << 3);
val |= (byte)(bit11Address & 0x07);
// Mark the message as extended.
val |= 1 << EXIDE;
WriteRegister(channel, TXB0SIDL, val);
// Write the 18 bit part of the ID
val = (byte)(bit18Address >> 8);
WriteRegister(channel, TXB0EID8, val);
val = (byte)(bit18Address);
WriteRegister(channel, TXB0EID0, val);
}
else
{
// Transmit a 11 bit ID.
bit11Address = (uint)(message.CANID);
val = (byte)(bit11Address >> 3);
WriteRegister(channel, TXB0SIDH, val);
val = (byte)(bit11Address << 5);
WriteRegister(channel, TXB0SIDL, val);
}
//--------------------------------------
val = (byte)(message.DataLength & 0x0f);
// Check if is a remote frame
if (message.IsRemote)
{
// Mark the frame as remote
val |= (byte)(1UL << (TXRTR));
WriteRegisterBit(channel, val, TXRTR, 1);
}
WriteRegister(channel, TXB0DLC, val);
//--------------------------------------
//Write Message Data
byte[] txDATA = new byte[10];
txDATA[0] = WRITE;
txDATA[1] = TXB0D0;
for (int i = DataIndexOffset; i < message.DataLength + DataIndexOffset; i++)
{
txDATA[i] = message.data[i - DataIndexOffset];
}
spi.Config = configSPI[channel];
spi.Write(txDATA);
//----------------------
// Command to transmit the CAN message
WriteRegisterBit(channel,TXB0CTRL, TXREQ, 1);
//----------------------
// Wait until time out to get confirmation of message was sent.
while (Utility.GetMachineTime() < endTime)
{
val = ReadRegister(channel, CANINTF);
if((val & TX0IF_MASK ) == TX0IF_MASK )
{
sentMessage = true;
break;
}
}
////Abort the send if failed
WriteRegisterBit(channel, TXB0CTRL, TXREQ, 0);
////And clear write interrupt
WriteRegisterBit(channel, CANINTF, TX0IF, 0);
return sentMessage;
}
/// <summary>
/// Check if a new message was received by the transceiver.
/// </summary>
/// <param name="msg">The CAN message that will contain the retrived message.</param>
/// <param name="timeout">The time to wait if a message become available.</param>
/// <returns>True if a message was received.</returns>
public bool Receive(uint channel,out CANMSG msg, int timeout)
{
bool gotMessage = false;
uint val;
msg = new CANMSG();
TimeSpan startTime = Utility.GetMachineTime();
TimeSpan endTime = startTime.Add(new TimeSpan(0, 0, 0, 0, timeout));
gotMessage = false;
while (Utility.GetMachineTime() < endTime)
{
val = ReadRegister(channel, CANINTF);
//If we have a message available, read it
if ((val & RX0IF_MASK) == RX0IF_MASK)
{
gotMessage = true;
break;
}
}
if (gotMessage)
{
val = ReadRegister(channel, RXB0CTRL);
msg.IsRemote = ((val & 0x04) == 0x04) ? true : false;
//Address received from
uint adddresVal = 0;
val = ReadRegister(channel, RXB0SIDH);
adddresVal |= (val << 3);
val = ReadRegister(channel, RXB0SIDL);
adddresVal |= (val >> 5);
bool isExtended = ((val & EXIDE_MASK) == EXIDE_MASK) ? true : false;
uint adddresExtVal = 0;
if (isExtended)
{
adddresExtVal = (uint)((val & 0x03) << 16);
val = ReadRegister(channel, RXB0EID8);
adddresExtVal |= (uint)(val << 8);
val = ReadRegister(channel, RXB0EID0);
adddresExtVal |= val;
adddresVal = ((adddresVal << 18) | adddresExtVal);
}
msg.CANID = (uint)adddresVal;
//Read data bytes
val = ReadRegister(channel,RXB0DLC);
uint dataLen = (val & 0xf);
byte[] CmdBuffer = new byte[] { READ, RXB0D0 };
msg.data = new byte[dataLen];
spi.Config = configSPI[channel];
spi.WriteRead(CmdBuffer, msg.data, 2);
//And clear read interrupt
WriteRegisterBit(channel,CANINTF, RX0IF, 0);
}
else
{
}
return gotMessage;
}
/// <summary>Set transceiver to normal state.</summary>
/// <remarks>This state needs to be selected before starting TX/RX.</remarks>
public void SetCANNormalMode()
{
//REQOP2<2:0> = 000 for normal mode
//ABAT = 0, do not abort pending transmission
//OSM = 0, not one shot
//CLKEN = 1, disable output clock
//CLKPRE = 0b11, clk/8
WriteRegister(0,CANCTRL,0x07);
WriteRegister(1,CANCTRL,0x07);
//Read mode and make sure it is normal
byte mode = ReadRegister(0,CANSTAT);
ReadRegister(1, CANSTAT);
mode = (byte)(mode >> 5);
if (mode != 0)
{ }
// Set RX buffer control to turn filters OFF and receive any message.
WriteRegister(0,RXB0CTRL, 0x60);
WriteRegister(1,RXB0CTRL, 0x60);
}
//--------------------------------------------------------------
// VMS_FilterInit()
//purpose : write the filter to CAN0'Receiver buf0 and buf1
// to receive the VMS_CAN0_ID and VMS_CAN1_ID
//-------------------------------------------------------------
private void VMS_FilterInit()
{
WriteRegister(0, RXF0SIDH, (byte)(VMS_CAN0_ID >> 3));
WriteRegister(0, RXF0SIDL , (byte)((VMS_CAN0_ID << 5)&0xe0));
WriteRegister(0, RXF1SIDH, (byte)(VMS_CAN1_ID >> 3));
WriteRegister(0, RXF1SIDL, (byte)((VMS_CAN1_ID << 5) & 0xe0));
WriteRegister(0, RXM0SIDH, 0xff); // config the MASK
WriteRegister(0, RXM0SIDL, 0xff);
}
//---------------------------------------------
public void VMS_CAN0IdFilter()
{
WriteRegister(0, RXB0CTRL, 0x0); // receive the standard/ext ID with RXF0 filter
}
//---------------------------------------------
public void VMS_CAN1IdFilter()
{
WriteRegister(0, RXB0CTRL, 0x1); // receive the standard/ext ID with RXF1 filter
}
//---------------------------------------------
public void SetConfigMode(uint channel)
{
WriteRegister(channel, CANCTRL, 0x87);
}
}
}
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