Enabled I2C_ASYNCH.

Author: anangl

hal/targets.json

@@ -1375,7 +1375,7 @@
         "supported_form_factors": ["ARDUINO"],
         "inherits": ["MCU_NRF51_32K"],
         "progen": {"target": "nrf51-dk"},
-        "device_has": ["ERROR_PATTERN", "I2C", "INTERRUPTIN", "PORTIN", "PORTINOUT", "PORTOUT", "RTC", "SERIAL", "SERIAL_ASYNCH", "SLEEP", "SPI", "SPI_ASYNCH"]
+        "device_has": ["ERROR_PATTERN", "I2C", "I2C_ASYNCH", "INTERRUPTIN", "PORTIN", "PORTINOUT", "PORTOUT", "RTC", "SERIAL", "SERIAL_ASYNCH", "SLEEP", "SPI", "SPI_ASYNCH"]
     },
     "NRF51_DK_BOOT": {
         "supported_form_factors": ["ARDUINO"],
@@ -1773,6 +1773,6 @@
             "NRF52_PAN_62",
             "NRF52_PAN_63"
         ],
-        "device_has": ["ERROR_PATTERN", "I2C", "INTERRUPTIN", "PORTIN", "PORTINOUT", "PORTOUT", "RTC", "SERIAL", "SERIAL_ASYNCH", "SLEEP", "SPI", "SPI_ASYNCH"]
+        "device_has": ["ERROR_PATTERN", "I2C", "I2C_ASYNCH", "INTERRUPTIN", "PORTIN", "PORTINOUT", "PORTOUT", "RTC", "SERIAL", "SERIAL_ASYNCH", "SLEEP", "SPI", "SPI_ASYNCH"]
     }
 }

hal/targets/hal/TARGET_NORDIC/TARGET_NRF5/i2c_api.c

@@ -122,7 +122,7 @@ void i2c_init(i2c_t *obj, PinName sda, PinName scl)
     }
 
     // No available peripheral
-    error("No available I2C");
+    error("No available I2C peripheral\r\n");
 }
 
 void i2c_reset(i2c_t *obj)
@@ -215,7 +215,7 @@ int i2c_byte_write(i2c_t *obj, int data)
 
 #if DEVICE_I2C_ASYNCH
 
-void i2c_transfer_asynch(i2c_t *obj, void *tx, size_t tx_length,
+void i2c_transfer_asynch(i2c_t *obj, const void *tx, size_t tx_length,
                          void *rx, size_t rx_length, uint32_t address,
                          uint32_t stop, uint32_t handler,
                          uint32_t event, DMAUsage hint)