LPC11C24: CanDriver::detectBitRate() - NOT TESTED, NOT FINISHED

libuavcan_drivers/lpc11c24/driver/include/uavcan_lpc11c24/can.hpp

@@ -29,6 +29,15 @@ public:
      */
     static CanDriver& instance() { return self; }
 
+    /**
+     * Attempts to detect bit rate of the CAN bus.
+     * This function may block for up to X seconds, where X is the number of bit rates to try.
+     * This function is NOT guaranteed to reset the CAN controller upon return.
+     * @return On success: detected bit rate, in bits per second.
+     *         On failure: zero.
+     */
+    static uavcan::uint32_t detectBitRate(void (*idle_callback)() = nullptr);
+
     /**
      * Returns negative value if the requested baudrate can't be used.
      * Returns zero if OK.

libuavcan_drivers/lpc11c24/driver/src/c_can.hpp

@@ -98,7 +98,7 @@ static_assert(offsetof(Type, IF[0].DB2) == 0x048, "C_CAN offset");
 static_assert(offsetof(Type, IF[1].DB2) == 0x0A8, "C_CAN offset");
 
 
-Type* const Can = reinterpret_cast<Type*>(0x40050000);
+Type& Can = *reinterpret_cast<Type*>(0x40050000);
 
 
 /*

libuavcan_drivers/lpc11c24/driver/src/can.cpp

@@ -156,6 +156,57 @@ BitTimingSettings computeBitTimings(std::uint32_t bitrate)
 
 CanDriver CanDriver::self;
 
+uavcan::uint32_t CanDriver::detectBitRate(void (*idle_callback)())
+{
+    static constexpr uavcan::uint32_t BitRatesToTry[] =
+    {
+        1000000,
+        500000,
+        250000,
+        125000
+    };
+
+    const auto ListeningDuration = uavcan::MonotonicDuration::fromMSec(1050);
+
+    Chip_Clock_EnablePeriphClock(SYSCTL_CLOCK_CAN);
+
+    for (auto bitrate : BitRatesToTry)
+    {
+        // Computing bit timings
+        const auto bit_timings = computeBitTimings(bitrate);
+        if (!bit_timings.isValid())
+        {
+            return 0;
+        }
+
+        // Configuring the CAN controller
+        {
+            CriticalSectionLocker locker;
+
+            c_can::Can.CNTL = c_can::CNTL_DAR | c_can::CNTL_CCE;
+
+            c_can::Can.BT     = bit_timings.canbtr;
+            c_can::Can.CLKDIV = bit_timings.canclkdiv;
+
+            c_can::Can.TEST = c_can::TEST_SILENT;
+
+            c_can::Can.CNTL = c_can::CNTL_DAR;
+        }
+
+        // Listening
+        const auto deadline = clock::getMonotonic() + ListeningDuration;
+        while (clock::getMonotonic() < deadline)
+        {
+            if (idle_callback != nullptr)
+            {
+                idle_callback();
+            }
+        }
+    }
+
+    return 0;
+}
+
 int CanDriver::init(uavcan::uint32_t bitrate)
 {
     CriticalSectionLocker locker;