NET OS 6.1 Training

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NETOS 6.1 Training
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I2C
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I2C device topics

• Introduction
• I2C APIs
• I2C examples

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I2C device basic

• Simple 4-wire device. Multiple I2C devices can
  be connected to the same I2C bus.
• We support two types (all) I2C devices I2C
  Master and I2C Slave.

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Performance

• We support 100Kbits/sec or 400Kbits/sec.
• Support 7 10 bit addressing
• Dedicated I/O. No change to the gpio.h

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IC2 Master Interface
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I2C Slave
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7bit addressing format
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10bit addressing format
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Device Open()

• Calls i2c_dev_open()
• Example
• i2cPort open("/i2c/0",I2C_SLAVE) or
• i2cPort open("/i2c/0",I2C_MASTER)
• I2C device channel /i2c/0
• I2C device mode I2C_MASTER, or I2C_SLAVE.

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Device close()

• Calls i2c_dev_close()
• Closes the I2C channel.
• Example
• ret close(fd)

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Device Read()

• Calls i2c_dev_read().
• int i2c_dev_read(int channel, void i2cMsg, int
  notUsed, int notUsed1)
• Note i2cMsg is pointer to the i2cMsg type.
• The i2cMeg will be returned by a read callback
  function in an ISR. DO NOT access it before it
  is returned.

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Device Write()

• Calls i2c_dev_write().
• int i2c_dev_write(int channel, void i2cMsg, int
  notUsed, int notUsed1)
• The i2cMsg will be returned by a write callback
  function in an ISR context.
• DO NOT access the message before it is returned.

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Device Ioctl()

• Calls i2c_dev_ioctl()
• Important flags
• I2C_SET_READ_CALLBACK_FUNC
• I2C_SET_WRITE_CALLBACK_FUNC
• I2C_SET_CLOCK_SPEED
• I2C_SET_GCA_IRQ_ENABLE
• I2C_FLUSH_BUFFER

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Other APIs

• void MCI2cBuildMsg(MC_I2C_MESSAGE_TYPE i2cMsg,
  char buf, unsigned long bufLength, unsigned char
  addr)

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I2C Specific.

• I2C driver is interrupt driven and the I2C
  interrupt is part of the BBUS interrupt. After
  we install the I2C interrupt function, on
  receiving every data byte and I2C commannd, we
  will receive an interrupt generated by the I2C
  IP. The MCI2cInterrupt() function will then be
  called by the ISR handler. Based on the state of
  the current I2C bus and whether the Mercury is
  acting as an I2C Master or Slave, the appropriate
  function will be called. Please refer to the I2C
  Master or Slave State machine for ISR handling
  details.
• A semaphore is used to keep multiple I2C port
  from opening at the same time.
• A Event flag is created in the application
  example but it is up to the application to
  decide whether to use it or not. The same
  applies to the Event flag in the nausbdevapp
  example as well.

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Example

• Typical User application
• A typical open function call is
• fd open(i2c/0, I2C_MASTER)
• Or
• fd open(i2c/0, I2C_SLAVE)
• A typical close function call is
• Ret close(fd)

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Read() Example

• Typical usage The third parameter is ignored.
• RetRead(fd, i2cMsg, 0x0)
• If (ret -1) printf( read failed.\n)

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Write() example

• Typical usage The third parameter is ignored.
• Retwrite(fd, i2cMsg, 0x0)
• If (ret -1) printf( write failed.\n)

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I2C message defination

• typedef struct _MESSAGE_TYPE
• char buffer
• unsigned short address
• unsigned long bufLength / size of the
  buffer /
• unsigned long availableDataLen
• MC_I2C_BUFFER_STATE state
• MC_I2C_MESSAGE_TYPE

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Typical write Callback function

• void writeCallBackFunc(MC_I2C_MESSAGE_TYPE
  ptrData)
• if (ptrData-gtstate ! I2C_INIT)
• tx_event_flags_set(i2cEvent,I2C_WRITE_EVENT_F
  LAG, TX_OR)
• / free(ptrData) /
• return

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Typical read callback function

• void readCallBackFunc(MC_I2C_MESSAGE_TYPE
  ptrData)
• if (ptrData-gtstate ! I2C_INIT)
• tx_event_flags_set(i2cEvent,I2C_READ_EVEN
  T_FLAG, TX_OR)
• / free(ptrData) /
• return

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Example application

• MCI2cBuildMsg(i2cMsg, ptrTemp, 26, 0x60)
• ret write(i2cPort, i2cMsg, 0)
• MCInstallIsr (I2C_INTERRUPT, (MC_ISR_HANDLER)
  MCI2cInterrupt, (void ) 0, 0)
• while( 1 / mySleepCount lt 6 /)
• ret tx_event_flags_get(i2cEvent,
  I2C_WRITE_EVENT_FLAGI2C_READ_EVENT_FLAG,
  TX_OR_CLEAR, actualEvent, TX_WAIT_FOREVER)

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Important files

• Driver Src/bsp/devices/i2c/
• Example
• Src/examples/nai2capp/itc_test.c