Wire (using member functions))

Wire (using member function)

The method using member functions has a relatively low level of abstraction and follows the general API system as provided by the C library. The procedures for operating the two-wire serial bus are more intuitive.

However, it is necessary to be explicitly aware of the start and end of bus usage.

Read

requestFrom()

size_type requestFrom(
    uint8_t u8address,
    size_type length,
    bool b_send_stop = true)

Reads the specified number of bytes at once. Since the result of reading is stored in a queue, call the .read() method immediately afterward until the queue is empty.

Parameters	Description
u8address	I2C address to be read
length	Number of bytes read
b_send_stop=true	When true, the STOP bit is set at the end of reading.
return type size_type	Number of bytes read. 0 means read failure.

Code Example

int len = Wire.requestFrom(0x70, 6);
for (int i = 0; i < 6; i++) {
  if (Wire.available()) {
		  au8data[i] = Wire.read();
    Serial.print(buff[i], HEX);
  }
}
// skip the rest (just in case)
// while (Wire.available()) Wire.read(); // normally, not necessary.

Writing

Writing is performed by the write() method after executing beginTransmission(). Call endTranmission() after a series of writing is finished.

	#define DEV_ADDR (0x70)
	const uint8_t msg[2] = 
	  {SHTC3_SOFT_RST_H, SHTC3_SOFT_RST_L};

	Wire.beginTransmission(DEV_ADDR);
	Wire.write(msg, sizeof(msg));
	Wire.endTransmission();

beginTransmission()

void beginTransmission(uint8_t address)

Initialize the export transfer. Call endTransmission() as soon as the writing process is finished.

Parameters	Description
u8address	I2C address to be written out

write(value)

size_type write(const value_type value)

Writes one byte.

Parameters	Description
Return value value	Bytes to be written.
Return value size_type	Number of bytes written. A value of 0 is an error.

write(*value, quantity)

size_type write(
  const value_type* value,
  size_type quantity)

Writes a byte sequence.

Parameters	Description
*value	the byte sequence to be written
Return value size_type	Number of bytes to be written.
Return value size_type	Number of bytes written. 0 is an error.

endTransmission()

uint8_t endTransmission(bool sendStop = true)

Processes the end of the export.

Parameters	Description
sendStop = true	Issue the STOP bit.
Return value uint8_t	0: Success 4: Failure