Fix bit timing for 500kbit

main.go

@@ -112,10 +112,11 @@ func sendMessages(txChan mcp2515.MsgChan) {
 	i := uint8(0)
 	for {
 		var message mcp2515.Message
-		message.Id = 0x110
+		message.Id = 0x2AA
 		message.Length = 8
-		message.Data[0] = i
-		message.Data[1] = 1
+		for j := 0; j < 8; j++ {
+			message.Data[j] = 0xAA
+		}
 		i += 1
 
 		select {

mcp2515/mcp2515.go

@@ -20,7 +20,6 @@ type MCP2515 struct {
 	mu          sync.RWMutex
 }
 
-
 // Prescalers for a 16 MHz oscillator with a 8 Time Quanta bit time
 var prescalers = map[int]int{
 	125000: 7,
@@ -49,9 +48,7 @@ func (d *MCP2515) Setup(baudRate int) error {
 	glog.V(1).Infof("mcp2515: setup")
 
 	d.baudRate = baudRate
-	//prescaler, ok := prescalers[baudRate]
-	prescaler := 3
-	ok := true
+	prescaler, ok := prescalers[baudRate]
 	if !ok {
 		return fmt.Errorf("Baud rate not supported %v", baudRate)
 	}
@@ -70,13 +67,13 @@ func (d *MCP2515) Setup(baudRate int) error {
 		initialCNF1(prescaler),
 	)
 
-	data, err := d.readRegister("CNF1", 1)
+	data, err := d.readRegister("CNF2", 1)
 
 	if err != nil {
 		return err
 	}
 
-	if data[0] != initialCNF1(prescaler) {
+	if data[0] != initialCNF2() {
 		return errors.New("CAN chip not responding")
 	}
 
@@ -99,7 +96,8 @@ func initialCNF2() uint8 {
 	// PHSEG1 = 3 TQ
 	// BTLMODE = 1 => Use CNF3 for PHSEG2
 	return (1 << bits["BTLMODE"]) |
-		(2 << bits["PHSEG10"])
+		(2 << bits["PHSEG10"]) |
+		(0 << bits["PRSEG"])
 }
 
 func initialCNF3() uint8 {

mcp2515/spi.go

@@ -13,7 +13,7 @@ func (d *MCP2515) writeRegister(register string, data ...uint8) error {
 		return err
 	}
 
-	glog.V(2).Infof("mcp2515: writeRegister %v", register)
+	glog.V(2).Infof("mcp2515: writeRegister %v=%v", register, data)
 
 	command := []uint8{commands["WRITE"], address}
 	buffer := append(command, data...)
@@ -27,27 +27,27 @@ func (d *MCP2515) readRegister(register string, length int) ([]uint8, error) {
 		return nil, err
 	}
 
-	glog.V(2).Infof("mcp2515: readRegister %v", register)
-
 	command := []uint8{commands["READ"], address}
 	buffer := make([]uint8, len(command) + length)
 	copy(buffer, command)
 
 	err = d.Bus.TransferAndReceiveData(buffer)
 	data := buffer[len(command):]
+
+	glog.V(2).Infof("mcp2515: readRegister %v=%v", register, data)
+
 	return data, err
 }
 
 func (d *MCP2515) readStatus() (uint8, error) {
-	glog.V(2).Infof("mcp2515: readStatus")
 	command := []uint8{commands["READ_STATUS"]}
 	buffer := make([]uint8, len(command) + 1)
 	copy(buffer, command)
 
 	err := d.Bus.TransferAndReceiveData(buffer)
 
 	data := buffer[len(command)]
-	glog.V(2).Infof("status=%v", data)
+	glog.V(4).Infof("mcp2515: readStatus=%v", data)
 
 	return data, err
 }
@@ -90,7 +90,7 @@ func (d *MCP2515) receiveMessage(rxBuffer uint8) (*Message, error) {
 	message := Message{
 		Id:       0,
 		Extended: (data[1] & (1 << bits["IDE"])) != 0,
-		Length:   (data[2] & 0xF),
+		Length:   (data[4] & 0xF),
 		Time:     time.Now(),
 	}