simplei2c.c File Reference

#include "simplei2c.h"

Functions
HUBTEXT i2c *	i2c_open (i2c *bus, int sclPin, int sdaPin, int sclDrive)
	Open an i2c device.
HUBTEXT void	i2c_start (i2c *bus)
	Signal i2c start condition on bus.
HUBTEXT void	i2c_stop (i2c *bus)
	Send Signal i2c stop condition on bus.
HUBTEXT int	i2c_writeByte (i2c *bus, int byte)
	Send i2c byte and return acknowledgement from device. Does not set start or stop. Drives SCL line if i2c device opened using sclDrive = 1.
HUBTEXT int	i2c_readByte (i2c *bus, int ackState)
	Receive i2c byte and reply with ack state. Does not set start or stop. Drives SCL line if i2c device opened using sclDrive = 1.
HUBTEXT int	i2c_writeData (i2c *bus, const unsigned char *data, int count)
	Send a block of i2c data. Does not set start or stop.
HUBTEXT int	i2c_readData (i2c *bus, unsigned char *data, int count)
	Receive a block of i2c data. Does not send start or stop conditions.
HUBTEXT int	i2c_poll (i2c *bus, int devaddr)
	Send i2c start and addr byte. Looks for ACK (0) or NACK (1). This is useful for checking if a device is responding or starting a new i2c packet. No stop is sent.

Detailed Description

Provides simple i2c start, stop, send, and receive functions

Copyright (c) 2013, Parallax Inc.

Function Documentation

HUBTEXT i2c* i2c_open	(	i2c *	bus,
		int	sclPin,
		int	sdaPin,
		int	sclDrive
	)

Open an i2c device.

Parameters

[in]	*bus	is a pointer to an i2c storage variable.
	sclPin	is the number of the Propeller I/O pin connected to the I2C bus' SCL line.
	sdaPin	is the number of the Propeller I/O pin connected to the I2C bus' SDA line.
	sclDrive	says drive SCL (1) or not (0). No SCL drive is by far the most common arrangement. Some Propeller boards do not apply a pull- up resistor to the EEPROM's SCL line, and driving the SCL pin is useful in for communicating with EEPROMs on those particular boards.

Returns

Copy of the bus address.

HUBTEXT int i2c_poll	(	i2c *	bus,
		int	addr
	)

Send i2c start and addr byte. Looks for ACK (0) or NACK (1). This is useful for checking if a device is responding or starting a new i2c packet. No stop is sent.

Parameters

*bus	is the bus pointer returned by i2c_open.
addr	is the I2C device address.

Returns

(ACK = 0_ if device has responded.

HUBTEXT int i2c_readByte	(	i2c *	bus,
		int	ackState
	)

Receive i2c byte and reply with ack state. Does not set start or stop. Drives SCL line if i2c device opened using sclDrive = 1.

Parameters

*bus	is the bus pointer returned by i2c_open.
ackState	sets or clears the acknowledge bit that follows the data byte in I2C. Acknowledge is ACK = 0, and no-acknowledge (NACK = 1).

Returns

The byte Propeller chip reads from I2C device.

HUBTEXT int i2c_readData	(	i2c *	bus,
		unsigned char *	data,
		int	count
	)

Receive a block of i2c data. Does not send start or stop conditions.

The Propeller replies with ACK after each byte received. After the last byte, it replies with NACK to tell the I2C device that it's done receiving bytes.

Drive scl if i2c device opened using sclDrive.

Parameters

*bus	is the bus pointer returned by i2c_open.
data	is a pointer to an array of unsigned char bytes.
count	is the number of bytes to receive.

Returns

the number of bytes sent.

HUBTEXT void i2c_start

(

i2c *

bus

)

Signal i2c start condition on bus.

Parameters

*bus	is the bus pointer returned by i2c_open.

HUBTEXT void i2c_stop

(

i2c *

bus

)

Send Signal i2c stop condition on bus.

Parameters

*bus	is the bus pointer returned by i2c_open.

HUBTEXT int i2c_writeByte	(	i2c *	bus,
		int	byte
	)

Send i2c byte and return acknowledgement from device. Does not set start or stop. Drives SCL line if i2c device opened using sclDrive = 1.

Parameters

*bus	is the bus pointer returned by i2c_open.
byte	is the data byte the Propeller chip sends to the I2C device.

Returns

Acknowledge bit value (ACK = 0) or no-acknowledge (NACK = 1) from receiving device.

HUBTEXT int i2c_writeData	(	i2c *	bus,
		const unsigned char *	data,
		int	count
	)

Send a block of i2c data. Does not set start or stop.

If the device replies with NACK after receiving a particular data byte, the transmit will terminate. Drive scl if i2c device opened using sclDrive.

Parameters

*bus	is the bus pointer returned by i2c_open.
*data	is a pointer to the array of data to send.
count	is the number of bytes to send.

Returns

the number of bytes sent (including address byte).