IIC library

Enumerations
enum	iic_index_t { IIC0 = 0, IIC1 = 1, NUM_IICS = 2 }

Functions
void	iic_init (const iic_index_t iic)
void	iic_destroy (const iic_index_t iic)
bool	iic_read_register (const iic_index_t iic, const uint8_t addr, const uint8_t reg, uint8_t *data, uint16_t length)
bool	iic_write_register (const iic_index_t iic, const uint8_t addr, const uint8_t reg, uint8_t *data, uint16_t length)
bool	iic_set_slave_mode (const iic_index_t iic, const uint8_t addr, uint32_t *register_map, const uint32_t rm_length)
void	iic_slave_mode_handler (const iic_index_t iic)
void	iic_reset (const iic_index_t iic)

Detailed Description

Functions to use the Inter-Integrated Circuit (IIC).

High-level functions to read/write to clients connected to the two integrated IIC modules. Before sending and receiving bytes the IIC2 must be connect to some I/O pins through the switchbox (see switchbox.h), e.g. Pmod A:

switchbox_set_pin(IO_PMODA3, SWB_IIC0_SCL);
switchbox_set_pin(IO_PMODA4, SWB_IIC0_SDA);

or the SCL and SDA Arduino IIC pins:

switchbox_set_pin(IO_AR_SCL, SWB_IIC0_SCL);
switchbox_set_pin(IO_AR_SDA, SWB_IIC0_SDA);

The Pmod A pins (see pinmap.h) are good because they have 2K2 pull-up resistors built in. If you want to use more than three IICs then you can use different pins with an external 2K2 pull-up resistor, which should work for more than three boards.

After that, an example of how to use this library for the MASTER.

#include <libpynq.h>
int main (void)
{
  // initialise all I/O
  pynq_init();
  iic_init(IIC0);
  uint32_t i;
  // you can use multiple slaves, here only one is shown
  uint32_t slave_address = 0x70;
  // read out all registers of the slave
  for (int reg=0; reg < 32; reg++) {
    if (iic_read_register(IIC0, slave_address, reg, (uint8_t *) &i, 4)) {
      // 4 means 4 bytes, do not change
      printf("register[%d]=error\n",reg); } else {
      printf("register[%d]=%d\n",reg,i);
    }
  }
  // clean up after use
  pynq_destroy();
  return EXIT_SUCCESS;
}

An example of how to use this library for the SLAVE.

int main(void)
{
  // this is the address by which this slave is reached by the master
  // different slaves must have different addresses
  const uint32_t my_slave_address = 0x70;
  // array contains 32 registers that can be written & read by the master
  // the slave can of course modify the values of the registers
  uint32_t my_register_map[32] = {1,2,3,4,5,6,7,8,9,10,11,12,13,
       14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32};
  const uint32_t my_register_map_length =
                       sizeof(my_register_mmap)/sizeof(uint32_t);
 
  pynq_init();
  iic_init(IIC0);
  iic_reset(IIC0);
  iic_set_slave_mode(IIC0, my_slave_address,
                     &(my_register_map[0]), my_register_map_length);
  while (1) {
    // the slave mode handler must be run regularly to react to the master
    iic_slave_mode_handler(IIC0);
    // insert your own code here, to do whatever the slave needs to do;
    // but ensure that you execute the slave mode handler regularly enough
    sleep_msec(10);
  }
  iic_destroy(IIC0);
  pynq_destroy();
  return EXIT_SUCCESS;
}

Enumeration Type Documentation

iic_index_t

enum iic_index_t

Enum of IICs. Functions use a switch numbered from 0..NUM_IICS-1.

Enumerator
IIC0
IIC1
NUM_IICS

Definition at line 114 of file iic.h.

Function Documentation

iic_destroy()

void iic_destroy

(

const iic_index_t

iic

)

Close the shared memory handle for the specified IIC index.

Parameters

uart	The IIC index to remove from the shared memory space.

Warning

Fails with program exit if the IIC channel is outside valid range.

Definition at line 3 of file iic.c.

iic_init()

void iic_init

(

const iic_index_t

iic

)

Initialize the IIC specified by the index with a shared memory handle and a buffer size of 4096 bytes.

Parameters

uart	The IIC index to initialize.

Warning

Fails with program exit if the IIC channel is outside valid range or when the shared memory system has not been instantiated.

Definition at line 2 of file iic.c.

iic_read_register()

bool iic_read_register	(	const iic_index_t	iic,
		const uint8_t	addr,
		const uint8_t	reg,
		uint8_t *	data,
		uint16_t	length
	)

Parameters

iic	The IIC index to initialize.
addr	The IIC address of the client to access.
reg	The clients register address.
data	Buffer where the register content is stored. [out]
length	The amount of data to read.

Reads the content of the register into data.

Returns

0 if successful, 1 on error

Definition at line 7 of file iic.c.

iic_reset()

void iic_reset

(

const iic_index_t

iic

)

Parameters

iic	The IIC index of the hardware to use. Return the IIC module into its default mode. This way it can be used as master.

Definition at line 6 of file iic.c.

iic_set_slave_mode()

bool iic_set_slave_mode	(	const iic_index_t	iic,
		const uint8_t	addr,
		uint32_t *	register_map,
		const uint32_t	rm_length
	)

Definition at line 4 of file iic.c.

iic_slave_mode_handler()

void iic_slave_mode_handler

(

const iic_index_t

iic

)

Parameters

iic	The IIC index of the hardware to use.

This handles requests that came in to the IIC unit when it is in slave mode.

Definition at line 302 of file iic.c.

iic_write_register()

bool iic_write_register	(	const iic_index_t	iic,
		const uint8_t	addr,
		const uint8_t	reg,
		uint8_t *	data,
		uint16_t	length
	)

Parameters

iic	The IIC index to initialize.
addr	The IIC address of the client to access.
reg	The clients register address.
data	Buffer where new the register content is stored.
length	The amount of data to write.

Writes data to register.

Returns

0 if successful, 1 on error

Definition at line 10 of file iic.c.