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Public Member Functions
I2CSlave Class Reference

An I2C Slave, used for communicating with an I2C Master device. More...

#include <I2CSlave.h>

Inheritance diagram for I2CSlave:
NonCopyable< I2CSlave >

Public Member Functions

 I2CSlave (PinName sda, PinName scl)
 Create an I2C Slave interface, connected to the specified pins. More...
 
void frequency (int hz)
 Set the frequency of the I2C interface. More...
 
void timeout (uint32_t timeout)
 Configure the timeout duration in microseconds for blocking transmission. More...
 
int receive (void)
 Check if this I2C Slave has been addressed. More...
 
int read (char *data, int length)
 Read specified number of bytes from an I2C master. More...
 
int read (void)
 Read a single byte from an I2C master. More...
 
int write (const char *data, int length)
 Write to an I2C master. More...
 
int write (int data)
 Write a single byte to an I2C master. More...
 
void address (int address)
 Set the I2C slave address. More...
 
void stop (void)
 Reset the I2C slave back into the known ready receiving state. More...
 

Detailed Description

An I2C Slave, used for communicating with an I2C Master device.

Note
Synchronization level: Not protected

Example Simple I2C responder:

#include <mbed.h>
const int SLAVE_ADDRESS = 0xA0;
const char message[] = "Slave!";
I2CSlave slave(I2C_SDA, I2C_SCL);
int main() {
slave.address(SLAVE_ADDRESS);
while (1) {
int operation = slave.receive();
switch (operation) {
case I2CSlave::ReadAddressed:
int status = slave.write(message, sizeof(message));
if (status == 0) {
printf("Written message: %s\n", message);
} else {
printf("Failed to write message.\n");
}
break;
case I2CSlave::WriteGeneral:
int byte_read = slave.read();
printf("Read General: %c (%d)\n", byte_read, byte_read);
break;
case I2CSlave::WriteAddressed:
int byte_read = slave.read();
printf("Read Addressed: %c (%d)\n", byte_read, byte_read);
break;
}
}
}

Definition at line 73 of file I2CSlave.h.

Constructor & Destructor Documentation

I2CSlave ( PinName  sda,
PinName  scl 
)

Create an I2C Slave interface, connected to the specified pins.

Parameters
sdaI2C data line pin.
sclI2C clock line pin.

Member Function Documentation

void address ( int  address)

Set the I2C slave address.

Parameters
addressThe address to set for the slave (least significant bit is ignored).
Note
If address is set to 0, the slave will only respond to the general call address.
void frequency ( int  hz)

Set the frequency of the I2C interface.

Parameters
hzThe bus frequency in Hertz.
int read ( char *  data,
int  length 
)

Read specified number of bytes from an I2C master.

Parameters
dataPointer to the buffer to read data into.
lengthNumber of bytes to read.
Returns
Result of the operation.
Return values
0If the number of bytes read is equal to length requested.
nonzeroOn error or if the number of bytes read is less than requested.
int read ( void  )

Read a single byte from an I2C master.

Returns
The byte read.
int receive ( void  )

Check if this I2C Slave has been addressed.

Returns
A status indicating if the device has been addressed and how.
Return values
NoDataThe slave has not been addressed.
ReadAddressedThe master has requested a read from this slave.
WriteAddressedThe master is writing to this slave.
WriteGeneralThe master is writing to all slave.
void stop ( void  )

Reset the I2C slave back into the known ready receiving state.

void timeout ( uint32_t  timeout)

Configure the timeout duration in microseconds for blocking transmission.

Parameters
timeoutTransmission timeout in microseconds.
Note
If no timeout is set the default timeout is used. Default timeout value is based on I2C frequency. Byte timeout is computed as triple amount of time it would take to send 10bit over I2C and is expressed by the formula: byte_timeout = 3 * (1/frequency * 10 * 1000000)
int write ( const char *  data,
int  length 
)

Write to an I2C master.

Parameters
dataPointer to the buffer containing the data to be sent.
lengthNumber of bytes to send.
Returns
Return values
0If written all bytes successfully.
nonzeroOn error or if the number of bytes written is less than requested.
int write ( int  data)

Write a single byte to an I2C master.

Parameters
dataValue to write.
Returns
Result of the operation.
Return values
0If a NACK is received.
1If an ACK is received.
2On timeout.
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