[mbed][tests] Add CAN loopback test case

Add test case that configures a MUT for in CAN self-test mode and sends a
series of test messages to verify that it works.

Author: devanlai

libraries/tests/mbed/can_loopback/main.cpp

@@ -0,0 +1,50 @@
+#include "mbed.h"
+#include "test_env.h"
+
+#if defined(TARGET_LPC1549)
+CAN can1(D9, D8);
+#elif defined(TARGET_LPC1768) || defined(TARGET_LPC4088)
+CAN can1(p9, p10);
+#endif
+
+#define TEST_ITERATIONS     127
+
+int main() {
+    MBED_HOSTTEST_TIMEOUT(20);
+    MBED_HOSTTEST_SELECT(dev_null);
+    MBED_HOSTTEST_DESCRIPTION(CAN Loopback);
+    MBED_HOSTTEST_START("MBED_A27");
+
+    can1.mode(CAN::Reset);
+
+    if (!can1.mode(CAN::LocalTest)) {
+        printf("Mode change failed\n");
+    }
+
+    char success_count = 0;
+    for (char i=0; i < TEST_ITERATIONS; i++) {
+        unsigned int id = 1337;
+        CANMessage tx_msg(id, &i, sizeof(i));
+        bool sent = false;
+        if (can1.write(tx_msg)) {
+            printf("Sent %u: %d\n", id, i);
+            sent = true;
+        }
+        wait_ms(50);
+
+        bool read = false;
+        CANMessage rx_msg;
+        if (can1.read(rx_msg)) {
+            printf("Read %u: %d\n", rx_msg.id, rx_msg.data[0]);
+            read = (rx_msg.id == id) && (rx_msg.data[0] == i);
+        }
+
+        bool success = sent && read;
+
+        if (success) {
+            success_count++;
+        }
+    }
+
+    MBED_HOSTTEST_RESULT(success_count == TEST_ITERATIONS);
+}

workspace_tools/tests.py

@@ -80,7 +80,12 @@
   * i2c_eeprom:
       * LPC1*: (SDA=p28 , SCL=p27)
       * KL25Z: (SDA=PTE0, SCL=PTE1)
-      
+
+  * can_transceiver:
+     * LPC1768: (RX=p9,   TX=p10)
+     * LPC1549: (RX=D9,   TX=D8)
+     * LPC4088: (RX=p9,   TX=p10)
+
 """
 TESTS = [
     # Automated MBED tests
@@ -270,6 +275,15 @@
         "automated": True,
         "duration": 10,
     },
+    {
+        "id": "MBED_A27", "description": "CAN loopback test",
+        "source_dir": join(TEST_DIR, "mbed", "can_loopback"),
+        "dependencies": [MBED_LIBRARIES, TEST_MBED_LIB],
+        "automated": True,
+        "duration": 20,
+        "peripherals": ["can_transceiver"],
+        "mcu": ["LPC1549", "LPC1768"],
+    },
     {
         "id": "MBED_BLINKY", "description": "Blinky",
         "source_dir": join(TEST_DIR, "mbed", "blinky"),