Add I2C support for nRF51

5 files changed, 723 insertions, 2 deletions

diff --git a/os/hal/boards/WVSHARE_BLE400/board.h b/os/hal/boards/WVSHARE_BLE400/board.h
index 0a93c20..57578b5 100644
--- a/os/hal/boards/WVSHARE_BLE400/board.h
+++ b/os/hal/boards/WVSHARE_BLE400/board.h
@@ -34,11 +34,12 @@
 #define LED4           22
 #define UART_TX        9
 #define UART_RX        11
-
 #define SPI_SCK        25
 #define SPI_MOSI       24
 #define SPI_MISO       23
 #define SPI_SS         30
+#define I2C_SCL        1
+#define I2C_SDA        0
 
 #if !defined(_FROM_ASM_)
 #ifdef __cplusplus
diff --git a/os/hal/ports/NRF51/NRF51822/i2c_lld.c b/os/hal/ports/NRF51/NRF51822/i2c_lld.c
new file mode 100644
index 0000000..611a004
--- /dev/null
+++ b/os/hal/ports/NRF51/NRF51822/i2c_lld.c
@@ -0,0 +1,446 @@
+/*

+    Copyright (C) 2015 Stephen Caudle

+

+    Licensed under the Apache License, Version 2.0 (the "License");

+    you may not use this file except in compliance with the License.

+    You may obtain a copy of the License at

+

+        http://www.apache.org/licenses/LICENSE-2.0

+

+    Unless required by applicable law or agreed to in writing, software

+    distributed under the License is distributed on an "AS IS" BASIS,

+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

+    See the License for the specific language governing permissions and

+    limitations under the License.

+*/

+

+/**

+ * @file    NRF51822/i2c_lld.c

+ * @brief   NRF51822 I2C subsystem low level driver source.

+ *

+ * @addtogroup I2C

+ * @{

+ */

+

+#include "osal.h"

+#include "hal.h"

+#include "nrf51_delay.h"

+

+#if HAL_USE_I2C || defined(__DOXYGEN__)

+

+/*===========================================================================*/

+/* Driver local definitions.                                                 */

+/*===========================================================================*/

+

+/* These macros are needed to see if the slave is stuck and we as master send dummy clock cycles to end its wait */

+#define I2C_HIGH(p)   do { NRF_GPIO->OUTSET = (1UL << (p)); } while(0)   /*!< Pulls I2C line high */

+#define I2C_LOW(p)    do { NRF_GPIO->OUTCLR = (1UL << (p)); } while(0)   /*!< Pulls I2C line low  */

+#define I2C_INPUT(p)  do { NRF_GPIO->DIRCLR = (1UL << (p)); } while(0)   /*!< Configures I2C pin as input  */

+#define I2C_OUTPUT(p) do { NRF_GPIO->DIRSET = (1UL << (p)); } while(0)   /*!< Configures I2C pin as output */

+

+#define I2C_PIN_CNF \

+      ((GPIO_PIN_CNF_SENSE_Disabled  << GPIO_PIN_CNF_SENSE_Pos) \

+      | (GPIO_PIN_CNF_DRIVE_S0D1     << GPIO_PIN_CNF_DRIVE_Pos) \

+      | (GPIO_PIN_CNF_PULL_Disabled  << GPIO_PIN_CNF_PULL_Pos)  \

+      | (GPIO_PIN_CNF_INPUT_Connect  << GPIO_PIN_CNF_INPUT_Pos) \

+      | (GPIO_PIN_CNF_DIR_Input      << GPIO_PIN_CNF_DIR_Pos))

+

+#define I2C_PIN_CNF_CLR \

+      ((GPIO_PIN_CNF_SENSE_Disabled  << GPIO_PIN_CNF_SENSE_Pos) \

+      | (GPIO_PIN_CNF_DRIVE_S0D1     << GPIO_PIN_CNF_DRIVE_Pos) \

+      | (GPIO_PIN_CNF_PULL_Disabled  << GPIO_PIN_CNF_PULL_Pos)  \

+      | (GPIO_PIN_CNF_INPUT_Connect  << GPIO_PIN_CNF_INPUT_Pos) \

+      | (GPIO_PIN_CNF_DIR_Output     << GPIO_PIN_CNF_DIR_Pos))

+

+#if NRF51_I2C_USE_I2C0

+#define I2C_IRQ_NUM     SPI0_TWI0_IRQn

+#define I2C_IRQ_PRI     NRF51_I2C_I2C0_IRQ_PRIORITY

+#elif NRF51_I2C_USE_I2C1

+#define I2C_IRQ_NUM     SPI1_TWI1_IRQn

+#define I2C_IRQ_PRI     NRF51_I2C_I2C1_IRQ_PRIORITY

+#endif

+

+/*===========================================================================*/

+/* Driver exported variables.                                                */

+/*===========================================================================*/

+

+/**

+ * @brief   I2C0 driver identifier.

+ */

+#if NRF51_I2C_USE_I2C0 || defined(__DOXYGEN__)

+I2CDriver I2CD1;

+#endif

+

+/**

+ * @brief   I2C1 driver identifier.

+ */

+#if NRF51_I2C_USE_I2C1 || defined(__DOXYGEN__)

+I2CDriver I2CD2;

+#endif

+

+uint8_t tx_resume_count;

+uint8_t rx_resume_count;

+uint8_t stop_count;

+

+/*===========================================================================*/

+/* Driver local variables and types.                                         */

+/*===========================================================================*/

+

+/*===========================================================================*/

+/* Driver local functions.                                                   */

+/*===========================================================================*/

+

+/**

+ * @brief Function for detecting stuck slaves (SDA = 0 and SCL = 1) and tries to clear the bus.

+ *

+ * @return

+ * @retval false Bus is stuck.

+ * @retval true Bus is clear.

+ */

+static void i2c_clear_bus(I2CDriver *i2cp)

+{

+  const I2CConfig *cfg = i2cp->config;

+  int i;

+

+  NRF_GPIO->PIN_CNF[cfg->scl_pad] = I2C_PIN_CNF;

+  NRF_GPIO->PIN_CNF[cfg->sda_pad] = I2C_PIN_CNF;

+

+  I2C_HIGH(cfg->sda_pad);

+  I2C_HIGH(cfg->scl_pad);

+

+  NRF_GPIO->PIN_CNF[cfg->scl_pad] = I2C_PIN_CNF_CLR;

+  NRF_GPIO->PIN_CNF[cfg->sda_pad] = I2C_PIN_CNF_CLR;

+

+  nrf_delay_us(4);

+

+  for(i = 0; i < 9; i++) {

+    if (palReadPad(IOPORT1, cfg->sda_pad)) {

+      if(i > 0)

+        break;

+      else

+        return;

+    }

+

+    I2C_LOW(cfg->scl_pad);

+    nrf_delay_us(4);

+    I2C_HIGH(cfg->scl_pad);

+    nrf_delay_us(4);

+  }

+

+  I2C_LOW(cfg->sda_pad);

+  nrf_delay_us(4);

+  I2C_HIGH(cfg->sda_pad);

+}

+

+static inline void i2c_setup_shortcut(I2CDriver *i2cp)

+{

+  uint32_t rxbytes = i2cp->rxbytes;

+  uint32_t txbytes = i2cp->txbytes;

+

+  osalDbgAssert(rxbytes + txbytes, "transfer must be greater than zero");

+

+  if (txbytes > 1 || (!txbytes && rxbytes > 1))

+    i2cp->i2c->SHORTS = TWI_SHORTS_BB_SUSPEND_Enabled << TWI_SHORTS_BB_SUSPEND_Pos;

+  else if (((txbytes == 1)  && !rxbytes) || ((rxbytes == 1) && !txbytes))

+    i2cp->i2c->SHORTS = TWI_SHORTS_BB_STOP_Enabled << TWI_SHORTS_BB_STOP_Pos;

+  else

+    i2cp->i2c->SHORTS = 0;

+}

+

+#if defined(__GNUC__)

+__attribute__((noinline))

+#endif

+/**

+ * @brief   Common IRQ handler.

+ * @note    Tries hard to clear all the pending interrupt sources, we don't

+ *          want to go through the whole ISR and have another interrupt soon

+ *          after.

+ *

+ * @param[in] i2cp         pointer to an I2CDriver

+ */

+static void serve_interrupt(I2CDriver *i2cp) {

+

+  NRF_TWI_Type *i2c = i2cp->i2c;

+

+  if(i2c->EVENTS_TXDSENT) {

+

+    i2c->EVENTS_TXDSENT = 0;

+

+    if(--i2cp->txbytes) {

+

+      i2c->TXD = *i2cp->txptr++;

+      i2c_setup_shortcut(i2cp);

+      i2c->TASKS_RESUME = 1;

+      tx_resume_count++;

+    }

+    else if (i2cp->rxbytes) {

+

+      i2c_setup_shortcut(i2cp);

+      i2c->TASKS_STARTRX = 1;

+    }

+  }

+  if(i2c->EVENTS_RXDREADY) {

+

+    i2c->EVENTS_RXDREADY = 0;

+    *i2cp->rxptr++ = i2c->RXD;

+

+    if(--i2cp->rxbytes) {

+      i2c_setup_shortcut(i2cp);

+      i2c->TASKS_RESUME = 1;

+      rx_resume_count++;

+    }

+  }

+  if(i2c->EVENTS_ERROR) {

+

+    uint32_t err = i2c->ERRORSRC;

+    i2c->EVENTS_ERROR = 0;

+

+    if (err & TWI_ERRORSRC_OVERRUN_Msk)

+      i2cp->errors |= I2C_OVERRUN;

+    if (err & (TWI_ERRORSRC_ANACK_Msk | TWI_ERRORSRC_DNACK_Msk))

+      i2cp->errors |= I2C_ACK_FAILURE;

+

+    i2c->TASKS_STOP = 1;

+    _i2c_wakeup_error_isr(i2cp);

+  } else if(i2c->EVENTS_STOPPED) {

+

+    stop_count++;

+    i2c->EVENTS_STOPPED = 0;

+    _i2c_wakeup_isr(i2cp);

+  }

+}

+

+/*===========================================================================*/

+/* Driver interrupt handlers.                                                */

+/*===========================================================================*/

+

+#if NRF51_I2C_USE_I2C0 || defined(__DOXYGEN__)

+

+OSAL_IRQ_HANDLER(Vector4C) {

+

+  OSAL_IRQ_PROLOGUE();

+  serve_interrupt(&I2CD1);

+  OSAL_IRQ_EPILOGUE();

+}

+

+#endif

+

+#if NRF51_I2C_USE_I2C1 || defined(__DOXYGEN__)

+

+OSAL_IRQ_HANDLER(Vector50) {

+

+  OSAL_IRQ_PROLOGUE();

+  serve_interrupt(&I2CD2);

+  OSAL_IRQ_EPILOGUE();

+}

+

+#endif

+

+/*===========================================================================*/

+/* Driver exported functions.                                                */

+/*===========================================================================*/

+

+/**

+ * @brief   Low level I2C driver initialization.

+ *

+ * @notapi

+ */

+void i2c_lld_init(void) {

+

+#if NRF51_I2C_USE_I2C0

+  i2cObjectInit(&I2CD1);

+  I2CD1.thread = NULL;

+  I2CD1.i2c = NRF_TWI0;

+#endif

+

+#if NRF51_I2C_USE_I2C1

+  i2cObjectInit(&I2CD2);

+  I2CD2.thread = NULL;

+  I2CD2.i2c = NRF_TWI1;

+#endif

+

+}

+

+/**

+ * @brief   Configures and activates the I2C peripheral.

+ *

+ * @param[in] i2cp      pointer to the @p I2CDriver object

+ *

+ * @notapi

+ */

+void i2c_lld_start(I2CDriver *i2cp) {

+

+  NRF_TWI_Type *i2c = i2cp->i2c;

+  const I2CConfig *cfg = i2cp->config;

+

+  if (i2cp->state != I2C_STOP)

+    return;

+

+  i2c_clear_bus(i2cp);

+

+  NRF_GPIO->PIN_CNF[cfg->scl_pad] = I2C_PIN_CNF;

+  NRF_GPIO->PIN_CNF[cfg->sda_pad] = I2C_PIN_CNF;

+

+  i2c->EVENTS_RXDREADY = 0;

+  i2c->EVENTS_TXDSENT = 0;

+  i2c->PSELSCL = cfg->scl_pad;

+  i2c->PSELSDA = cfg->sda_pad;

+

+  switch (cfg->clock) {

+    case 100000:

+      i2c->FREQUENCY = TWI_FREQUENCY_FREQUENCY_K100 << TWI_FREQUENCY_FREQUENCY_Pos;

+      break;

+    case 250000:

+      i2c->FREQUENCY = TWI_FREQUENCY_FREQUENCY_K250 << TWI_FREQUENCY_FREQUENCY_Pos;

+      break;

+    case 400000:

+      i2c->FREQUENCY = TWI_FREQUENCY_FREQUENCY_K400 << TWI_FREQUENCY_FREQUENCY_Pos;

+      break;

+    default:

+      osalDbgAssert(0, "invalid I2C frequency");

+      break;

+  };

+

+  nvicEnableVector(I2C_IRQ_NUM, I2C_IRQ_PRI);

+

+  i2c->INTENSET = TWI_INTENSET_TXDSENT_Msk | TWI_INTENSET_STOPPED_Msk |

+    TWI_INTENSET_ERROR_Msk | TWI_INTENSET_RXDREADY_Msk;

+

+  i2c->ENABLE = TWI_ENABLE_ENABLE_Enabled << TWI_ENABLE_ENABLE_Pos;

+}

+

+/**

+ * @brief   Deactivates the I2C peripheral.

+ *

+ * @param[in] i2cp      pointer to the @p I2CDriver object

+ *

+ * @notapi

+ */

+void i2c_lld_stop(I2CDriver *i2cp) {

+

+  NRF_TWI_Type *i2c = i2cp->i2c;

+  const I2CConfig *cfg = i2cp->config;

+

+  if (i2cp->state != I2C_STOP) {

+

+    i2c->ENABLE = TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos;

+

+    i2c->INTENCLR = TWI_INTENSET_TXDSENT_Msk | TWI_INTENSET_STOPPED_Msk |

+      TWI_INTENSET_ERROR_Msk | TWI_INTENSET_RXDREADY_Msk;

+

+    nvicDisableVector(I2C_IRQ_NUM);

+

+    NRF_GPIO->PIN_CNF[cfg->scl_pad] = I2C_PIN_CNF_CLR;

+    NRF_GPIO->PIN_CNF[cfg->sda_pad] = I2C_PIN_CNF_CLR;

+  }

+}

+

+static inline msg_t _i2c_txrx_timeout(I2CDriver *i2cp, i2caddr_t addr,

+                                      const uint8_t *txbuf, size_t txbytes,

+                                      uint8_t *rxbuf, size_t rxbytes,

+                                      systime_t timeout) {

+

+  NRF_TWI_Type *i2c = i2cp->i2c;

+

+  (void)timeout;

+  msg_t msg;

+

+  i2cp->errors = I2C_NO_ERROR;

+  i2cp->addr = addr;

+

+  i2cp->txptr = txbuf;

+  i2cp->txbytes = txbytes;

+

+  i2cp->rxptr = rxbuf;

+  i2cp->rxbytes = rxbytes;

+

+  i2c->ADDRESS = addr;

+

+  tx_resume_count = 0;

+  rx_resume_count = 0;

+  stop_count = 0;

+

+  if (i2cp->txbytes) {

+

+    i2c->TXD = *i2cp->txptr++;

+    i2c_setup_shortcut(i2cp);

+    i2c->TASKS_STARTTX = 1;

+  } else if (i2cp->rxbytes) {

+

+    i2c_setup_shortcut(i2cp);

+    i2c->TASKS_STARTRX = 1;

+  } else {

+

+    osalDbgAssert(0, "no bytes to transfer");

+  }

+

+  msg = osalThreadSuspendTimeoutS(&i2cp->thread, timeout);

+

+  if (msg == MSG_TIMEOUT)

+    i2c->TASKS_STOP = 1;

+

+  return msg;

+}

+

+/**

+ * @brief   Receives data via the I2C bus as master.

+ *

+ * @param[in] i2cp      pointer to the @p I2CDriver object

+ * @param[in] addr      slave device address

+ * @param[out] rxbuf    pointer to the receive buffer

+ * @param[in] rxbytes   number of bytes to be received

+ * @param[in] timeout   the number of ticks before the operation timeouts,

+ *                      the following special values are allowed:

+ *                      - @a TIME_INFINITE no timeout.

+ *                      .

+ * @return              The operation status.

+ * @retval MSG_OK       if the function succeeded.

+ * @retval MSG_RESET    if one or more I2C errors occurred, the errors can

+ *                      be retrieved using @p i2cGetErrors().

+ * @retval MSG_TIMEOUT  if a timeout occurred before operation end. <b>After a

+ *                      timeout the driver must be stopped and restarted

+ *                      because the bus is in an uncertain state</b>.

+ *

+ * @notapi

+ */

+msg_t i2c_lld_master_receive_timeout(I2CDriver *i2cp, i2caddr_t addr,

+                                     uint8_t *rxbuf, size_t rxbytes,

+                                     systime_t timeout) {

+

+  return _i2c_txrx_timeout(i2cp, addr, NULL, 0, rxbuf, rxbytes, timeout);

+}

+

+/**

+ * @brief   Transmits data via the I2C bus as master.

+ *

+ * @param[in] i2cp      pointer to the @p I2CDriver object

+ * @param[in] addr      slave device address

+ * @param[in] txbuf     pointer to the transmit buffer

+ * @param[in] txbytes   number of bytes to be transmitted

+ * @param[out] rxbuf    pointer to the receive buffer

+ * @param[in] rxbytes   number of bytes to be received

+ * @param[in] timeout   the number of ticks before the operation timeouts,

+ *                      the following special values are allowed:

+ *                      - @a TIME_INFINITE no timeout.

+ *                      .

+ * @return              The operation status.

+ * @retval MSG_OK       if the function succeeded.

+ * @retval MSG_RESET    if one or more I2C errors occurred, the errors can

+ *                      be retrieved using @p i2cGetErrors().

+ * @retval MSG_TIMEOUT  if a timeout occurred before operation end. <b>After a

+ *                      timeout the driver must be stopped and restarted

+ *                      because the bus is in an uncertain state</b>.

+ *

+ * @notapi

+ */

+msg_t i2c_lld_master_transmit_timeout(I2CDriver *i2cp, i2caddr_t addr,

+                                      const uint8_t *txbuf, size_t txbytes,

+                                      uint8_t *rxbuf, size_t rxbytes,

+                                      systime_t timeout) {

+

+  return _i2c_txrx_timeout(i2cp, addr, txbuf, txbytes, rxbuf, rxbytes, timeout);

+}

+

+#endif /* HAL_USE_I2C */

+

+/** @} */

diff --git a/os/hal/ports/NRF51/NRF51822/i2c_lld.h b/os/hal/ports/NRF51/NRF51822/i2c_lld.h
new file mode 100644
index 0000000..be3ea5b
--- /dev/null
+++ b/os/hal/ports/NRF51/NRF51822/i2c_lld.h
@@ -0,0 +1,222 @@
+/*

+    Copyright (C) 2015 Stephen Caudle

+

+    Licensed under the Apache License, Version 2.0 (the "License");

+    you may not use this file except in compliance with the License.

+    You may obtain a copy of the License at

+

+        http://www.apache.org/licenses/LICENSE-2.0

+

+    Unless required by applicable law or agreed to in writing, software

+    distributed under the License is distributed on an "AS IS" BASIS,

+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

+    See the License for the specific language governing permissions and

+    limitations under the License.

+*/

+

+/**

+ * @file    NRF51822/i2c_lld.h

+ * @brief   NRF51822 I2C subsystem low level driver header.

+ *

+ * @addtogroup I2C

+ * @{

+ */

+

+#ifndef _I2C_LLD_H_

+#define _I2C_LLD_H_

+

+#if HAL_USE_I2C || defined(__DOXYGEN__)

+

+/*===========================================================================*/

+/* Driver constants.                                                         */

+/*===========================================================================*/

+

+#define STATE_STOP    0x00

+#define STATE_SEND    0x01

+#define STATE_RECV    0x02

+#define STATE_DUMMY   0x03

+

+/*===========================================================================*/

+/* Driver pre-compile time settings.                                         */

+/*===========================================================================*/

+

+/**

+ * @name    Configuration options

+ * @{

+ */

+/**

+ * @brief   I2C0 driver enable switch.

+ * @details If set to @p TRUE the support for I2C0 is included.

+ * @note    The default is @p FALSE.

+ */

+#if !defined(NRF51_I2C_USE_I2C0) || defined(__DOXYGEN__)

+#define NRF51_I2C_USE_I2C0               FALSE

+#endif

+

+/**

+ * @brief   I2C1 driver enable switch.

+ * @details If set to @p TRUE the support for I2C1 is included.

+ * @note    The default is @p FALSE.

+ */

+#if !defined(NRF51_I2C_USE_I2C1) || defined(__DOXYGEN__)

+#define NRF51_I2C_USE_I2C1               FALSE

+#endif

+

+/**

+ * @brief   I2C0 interrupt priority level setting.

+ */

+#if !defined(NRF51_I2C_I2C0_IRQ_PRIORITY) || defined(__DOXYGEN__)

+#define NRF51_I2C_I2C0_IRQ_PRIORITY         10

+#endif

+

+/**

+ * @brief   I2C1 interrupt priority level setting.

+ */

+#if !defined(NRF51_I2C_I2C1_IRQ_PRIORITY) || defined(__DOXYGEN__)

+#define NRF51_I2C_I2C1_IRQ_PRIORITY         10

+#endif

+/** @} */

+

+/*===========================================================================*/

+/* Derived constants and error checks.                                       */

+/*===========================================================================*/

+

+/*===========================================================================*/

+/* Driver data structures and types.                                         */

+/*===========================================================================*/

+

+/* @brief Type representing I2C address. */

+typedef uint8_t i2caddr_t;

+

+/* @brief Type of I2C Driver condition flags. */

+typedef uint32_t i2cflags_t;

+

+/* @brief Type used to control the ISR state machine. */

+typedef uint8_t intstate_t;

+

+/**

+ * @brief   Driver configuration structure.

+ * @note    Implementations may extend this structure to contain more,

+ *          architecture dependent, fields.

+ */

+

+/**

+ * @brief Driver configuration structure.

+ */

+typedef struct {

+

+  /* @brief Clock to be used for the I2C bus. */

+  uint32_t             clock;

+  /* @brief Pad number for SCL */

+  uint8_t              scl_pad;

+  /* @brief Pad number for SDA */

+  uint8_t              sda_pad;

+

+} I2CConfig;

+

+/**

+ * @brief   Type of a structure representing an I2C driver.

+ */

+typedef struct I2CDriver I2CDriver;

+

+/**

+ * @brief Structure representing an I2C driver.

+ */

+struct I2CDriver {

+  /**

+   * @brief   Driver state.

+   */

+  i2cstate_t                state;

+  /**

+   * @brief   Current configuration data.

+   */

+  const I2CConfig           *config;

+  /**

+   * @brief   Error flags.

+   */

+  i2cflags_t                errors;

+#if I2C_USE_MUTUAL_EXCLUSION || defined(__DOXYGEN__)

+#if CH_CFG_USE_MUTEXES || defined(__DOXYGEN__)

+  /**

+   * @brief   Mutex protecting the bus.

+   */

+  mutex_t                   mutex;

+#elif CH_CFG_USE_SEMAPHORES

+  semaphore_t               semaphore;

+#endif

+#endif /* I2C_USE_MUTUAL_EXCLUSION */

+#if defined(I2C_DRIVER_EXT_FIELDS)

+  I2C_DRIVER_EXT_FIELDS

+#endif

+  /* @brief Thread waiting for I/O completion. */

+  thread_reference_t        thread;

+  /* @brief     Current slave address without R/W bit. */

+  i2caddr_t                 addr;

+

+  /* End of the mandatory fields.*/

+

+  /* @brief Pointer to the buffer with data to send. */

+  const uint8_t             *txptr;

+  /* @brief Number of bytes of data to send. */

+  size_t                    txbytes;

+  /* @brief Pointer to the buffer to put received data. */

+  uint8_t                   *rxptr;

+  /* @brief Number of bytes of data to receive. */

+  size_t                    rxbytes;

+  /* @brief Tracks current ISR state. */

+  intstate_t                intstate;

+  /* @brief Low-level register access. */

+  NRF_TWI_Type              *i2c;

+};

+

+/*===========================================================================*/

+/* Driver macros.                                                            */

+/*===========================================================================*/

+

+/**

+ * @brief   Get errors from I2C driver.

+ *

+ * @param[in] i2cp      pointer to the @p I2CDriver object

+ *

+ * @notapi

+ */

+#define i2c_lld_get_errors(i2cp) ((i2cp)->errors)

+

+/*===========================================================================*/

+/* External declarations.                                                    */

+/*===========================================================================*/

+

+#if !defined(__DOXYGEN__)

+

+#if NRF51_I2C_USE_I2C0

+extern I2CDriver I2CD1;

+#endif

+

+#if NRF51_I2C_USE_I2C1

+extern I2CDriver I2CD2;

+#endif

+

+#endif

+

+#ifdef __cplusplus

+extern "C" {

+#endif

+  void i2c_lld_init(void);

+  void i2c_lld_start(I2CDriver *i2cp);

+  void i2c_lld_stop(I2CDriver *i2cp);

+  msg_t i2c_lld_master_transmit_timeout(I2CDriver *i2cp, i2caddr_t addr,

+                                        const uint8_t *txbuf, size_t txbytes,

+                                        uint8_t *rxbuf, size_t rxbytes,

+                                        systime_t timeout);

+  msg_t i2c_lld_master_receive_timeout(I2CDriver *i2cp, i2caddr_t addr,

+                                       uint8_t *rxbuf, size_t rxbytes,

+                                       systime_t timeout);

+#ifdef __cplusplus

+}

+#endif

+

+#endif /* HAL_USE_I2C */

+

+#endif /* _I2C_LLD_H_ */

+

+/** @} */

diff --git a/os/hal/ports/NRF51/NRF51822/nrf51_delay.h b/os/hal/ports/NRF51/NRF51822/nrf51_delay.h
new file mode 100644
index 0000000..2a672db
--- /dev/null
+++ b/os/hal/ports/NRF51/NRF51822/nrf51_delay.h
@@ -0,0 +1,51 @@
+/*
+    Copyright (C) 2015 Stephen Caudle
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+        http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+*/
+
+/**
+ * @file    NRF51822/nrf51_delay.h
+ * @brief   NRF51822 Delay routines
+ *
+ * @{
+ */
+
+#ifndef _NRF_DELAY_H
+#define _NRF_DELAY_H
+
+inline static void nrf_delay_us(uint32_t volatile number_of_us) __attribute__((always_inline));
+inline static void nrf_delay_us(uint32_t volatile number_of_us)
+{
+register uint32_t delay asm ("r0") = number_of_us;
+__asm volatile (
+".syntax unified\n"
+    "1:\n"
+    " SUBS %0, %0, #1\n"
+    " NOP\n"
+    " NOP\n"
+    " NOP\n"
+    " NOP\n"
+    " NOP\n"
+    " NOP\n"
+    " NOP\n"
+    " NOP\n"
+    " NOP\n"
+    " NOP\n"
+    " NOP\n"
+    " NOP\n"
+    " BNE 1b\n"
+    ".syntax divided\n"
+    : "+r" (delay));
+}
+#endif //__NRF_DELAY_H
diff --git a/os/hal/ports/NRF51/NRF51822/platform.mk b/os/hal/ports/NRF51/NRF51822/platform.mk
index 885b16e..35c71fa 100644
--- a/os/hal/ports/NRF51/NRF51822/platform.mk
+++ b/os/hal/ports/NRF51/NRF51822/platform.mk
@@ -6,7 +6,8 @@ PLATFORMSRC = ${CHIBIOS}/os/hal/ports/common/ARMCMx/nvic.c \
               ${CHIBIOS}/community/os/hal/ports/NRF51/NRF51822/st_lld.c \
               ${CHIBIOS}/community/os/hal/ports/NRF51/NRF51822/spi_lld.c \
               ${CHIBIOS}/community/os/hal/ports/NRF51/NRF51822/ext_lld_isr.c \
-              ${CHIBIOS}/community/os/hal/ports/NRF51/NRF51822/ext_lld.c
+              ${CHIBIOS}/community/os/hal/ports/NRF51/NRF51822/ext_lld.c \
+              ${CHIBIOS}/community/os/hal/ports/NRF51/NRF51822/i2c_lld.c
 
 # Required include directories
 PLATFORMINC = ${CHIBIOS}/os/hal/ports/common/ARMCMx \