Merge pull request #19 from leres/master

Add MCP2515::setClkOut() to allow use of the CLKOUT prescaler

Author: autowp

mcp2515.cpp

@@ -226,7 +226,7 @@ MCP2515::ERROR MCP2515::setBitrate(const CAN_SPEED canSpeed, CAN_CLOCK canClock)
             cfg3 = MCP_8MHz_31k25BPS_CFG3;
             break;
 
-            case (CAN_33KBPS):                                             //  33.33KBPS
+            case (CAN_33KBPS):                                              //  33.333KBPS
             cfg1 = MCP_8MHz_33k3BPS_CFG1;
             cfg2 = MCP_8MHz_33k3BPS_CFG2;
             cfg3 = MCP_8MHz_33k3BPS_CFG3;
@@ -313,7 +313,7 @@ MCP2515::ERROR MCP2515::setBitrate(const CAN_SPEED canSpeed, CAN_CLOCK canClock)
             cfg3 = MCP_16MHz_20kBPS_CFG3;
             break;
 
-            case (CAN_33KBPS):                                              //  20Kbps
+            case (CAN_33KBPS):                                              //  33.333Kbps
             cfg1 = MCP_16MHz_33k3BPS_CFG1;
             cfg2 = MCP_16MHz_33k3BPS_CFG2;
             cfg3 = MCP_16MHz_33k3BPS_CFG3;
@@ -336,7 +336,7 @@ MCP2515::ERROR MCP2515::setBitrate(const CAN_SPEED canSpeed, CAN_CLOCK canClock)
             cfg3 = MCP_16MHz_80kBPS_CFG3;
             break;
 
-            case (CAN_83K3BPS):                                              //  83.3333Kbps
+            case (CAN_83K3BPS):                                             //  83.333Kbps
             cfg1 = MCP_16MHz_83k3BPS_CFG1;
             cfg2 = MCP_16MHz_83k3BPS_CFG2;
             cfg3 = MCP_16MHz_83k3BPS_CFG3;
@@ -387,6 +387,12 @@ MCP2515::ERROR MCP2515::setBitrate(const CAN_SPEED canSpeed, CAN_CLOCK canClock)
         case (MCP_20MHZ):
         switch (canSpeed)
         {
+            case (CAN_33KBPS):                                              //  33.333Kbps
+            cfg1 = MCP_20MHz_33k3BPS_CFG1;
+            cfg2 = MCP_20MHz_33k3BPS_CFG2;
+            cfg3 = MCP_20MHz_33k3BPS_CFG3;
+	    break;
+
             case (CAN_40KBPS):                                              //  40Kbps
             cfg1 = MCP_20MHz_40kBPS_CFG1;
             cfg2 = MCP_20MHz_40kBPS_CFG2;
@@ -405,6 +411,12 @@ MCP2515::ERROR MCP2515::setBitrate(const CAN_SPEED canSpeed, CAN_CLOCK canClock)
             cfg3 = MCP_20MHz_80kBPS_CFG3;
             break;
 
+            case (CAN_83K3BPS):                                             //  83.333Kbps
+            cfg1 = MCP_20MHz_83k3BPS_CFG1;
+            cfg2 = MCP_20MHz_83k3BPS_CFG2;
+            cfg3 = MCP_20MHz_83k3BPS_CFG3;
+	    break;
+
             case (CAN_100KBPS):                                             // 100Kbps
             cfg1 = MCP_20MHz_100kBPS_CFG1;
             cfg2 = MCP_20MHz_100kBPS_CFG2;
@@ -452,7 +464,6 @@ MCP2515::ERROR MCP2515::setBitrate(const CAN_SPEED canSpeed, CAN_CLOCK canClock)
         break;
     }
 
-
     if (set) {
         setRegister(MCP_CNF1, cfg1);
         setRegister(MCP_CNF2, cfg2);
@@ -464,6 +475,31 @@ MCP2515::ERROR MCP2515::setBitrate(const CAN_SPEED canSpeed, CAN_CLOCK canClock)
     }
 }
 
+MCP2515::ERROR MCP2515::setClkOut(const CAN_CLKOUT divisor)
+{
+    ERROR res;
+    uint8_t cfg3;
+
+    if (divisor == CLKOUT_DISABLE) {
+	/* Turn off CLKEN */
+	modifyRegister(MCP_CANCTRL, CANCTRL_CLKEN, 0x00);
+
+	/* Turn on CLKOUT for SOF */
+	modifyRegister(MCP_CNF3, CNF3_SOF, CNF3_SOF);
+        return ERROR_OK;
+    }
+
+    /* Set the prescaler (CLKPRE) */
+    modifyRegister(MCP_CANCTRL, CANCTRL_CLKPRE, divisor);
+
+    /* Turn on CLKEN */
+    modifyRegister(MCP_CANCTRL, CANCTRL_CLKEN, CANCTRL_CLKEN);
+
+    /* Turn off CLKOUT for SOF */
+    modifyRegister(MCP_CNF3, CNF3_SOF, 0x00);
+    return ERROR_OK;
+}
+
 void MCP2515::prepareId(uint8_t *buffer, const bool ext, const uint32_t id)
 {
     uint16_t canid = (uint16_t)(id & 0x0FFFF);

mcp2515.h

@@ -149,6 +149,10 @@
 #define MCP_20MHz_100kBPS_CFG2 (0xFA)
 #define MCP_20MHz_100kBPS_CFG3 (0x87)
 
+#define MCP_20MHz_83k3BPS_CFG1 (0x04)
+#define MCP_20MHz_83k3BPS_CFG2 (0xFE)
+#define MCP_20MHz_83k3BPS_CFG3 (0x87)
+
 #define MCP_20MHz_80kBPS_CFG1 (0x04)
 #define MCP_20MHz_80kBPS_CFG2 (0xFF)
 #define MCP_20MHz_80kBPS_CFG3 (0x87)
@@ -161,6 +165,10 @@
 #define MCP_20MHz_40kBPS_CFG2 (0xFF)
 #define MCP_20MHz_40kBPS_CFG3 (0x87)
 
+#define MCP_20MHz_33k3BPS_CFG1 (0x0B)
+#define MCP_20MHz_33k3BPS_CFG2 (0xFF)
+#define MCP_20MHz_33k3BPS_CFG3 (0x87)
+
 enum CAN_CLOCK {
     MCP_20MHZ,
     MCP_16MHZ,
@@ -186,6 +194,14 @@ enum CAN_SPEED {
     CAN_1000KBPS
 };
 
+enum CAN_CLKOUT {
+    CLKOUT_DISABLE = -1,
+    CLKOUT_DIV1 = 0x0,
+    CLKOUT_DIV2 = 0x1,
+    CLKOUT_DIV4 = 0x2,
+    CLKOUT_DIV8 = 0x3,
+};
+
 class MCP2515
 {
     public:
@@ -264,6 +280,8 @@ class MCP2515
         static const uint8_t CANSTAT_OPMOD = 0xE0;
         static const uint8_t CANSTAT_ICOD = 0x0E;
 
+        static const uint8_t CNF3_SOF = 0x80;
+
         static const uint8_t TXB_EXIDE_MASK = 0x08;
         static const uint8_t DLC_MASK       = 0x0F;
         static const uint8_t RTR_MASK       = 0x40;
@@ -298,7 +316,6 @@ class MCP2515
             TXB_TXP    = 0x03
         };
 
-
         static const uint8_t EFLG_ERRORMASK = EFLG_RX1OVR
                                             | EFLG_RX0OVR
                                             | EFLG_TXBO
@@ -446,6 +463,7 @@ class MCP2515
         ERROR setSleepMode();
         ERROR setLoopbackMode();
         ERROR setNormalMode();
+        ERROR setClkOut(const CAN_CLKOUT divisor);
         ERROR setBitrate(const CAN_SPEED canSpeed);
         ERROR setBitrate(const CAN_SPEED canSpeed, const CAN_CLOCK canClock);
         ERROR setFilterMask(const MASK num, const bool ext, const uint32_t ulData);