cI2C

Arduino Hardware I2C for AVR (plain c)

Hardware I2C library for AVR MCUs (lib intended for I2C protocols development in c, for easier ports to other MCUs)

Library choice:

• cI2C library implements I2C bus for AVR tagets (Uno, Nano, Mega...)
  • you may prefer this one when:
    • working on AVR targets
    • interrupts are not needed
• WireWrapper implements I2C bus for every platform that includes Wire library
  • you would have to use this one when:
    • working on non-AVR targets
    • portability is needed (using Wire library)

No refactoring is required when switching between cI2C & WireWrapper libs; Both libs share same Typedefs, Functions & Parameters.

Notes:

• cI2C is written in plain c (intentionally)
• cI2C does not use any interrupt (yet, but soon will have to)
• cI2C is designed to act as bus Master (Slave mode will be considered in future releases)
• cI2C is set to work on AVR targets only
  • for other targets, you may use WireWrapper instead (will be using Wire)

Usage:

This library is intended to be able to work with multiple slaves connected on the same I2C bus. Thus, the I2C bus and Slaves are defined separately.

• On one hand, I2C bus has to be initialised with appropriate speed:
  • use I2C_init(speed): speed can be choosen from I2C_SPEED enum for convenience, or passing an integer as parameter
• On the other hand, Slave(s) have to be defined and initialised too:
  • use I2C_SLAVE typedef to declare slaves structs
  • use I2C_slave_init(pSlave, addr, regsize)
    • pSlave is a pointer to the slave struct to initialise
    • addr is the slave I2C address (don't shift addr, lib takes care of that)
    • regsize is the width of internal slave registers (to be choosen from I2C_INT_SIZE)
  • in case you need to use custom R/W procedures for a particular slave:
    • use I2C_slave_set_rw_func(pSlave, pFunc, rw)
      • pSlave is a pointer to the slave declaration to initialise
      • pFunc is a pointer to the Read or Write bypass function
      • rw can be choosen from I2C_RW enum (wr=0, rd=1)

After all inits are done, the lib can basically be used this way:

• I2C_read(pSlave, regaddr, pData, bytes)
  • pSlave is a pointer to the slave struct to read from
  • regaddr is the start address to read from
  • pData is a pointer to the place where datas read will be stored
  • bytes number of bytes to read from slave
  • returns true if read is ok, false otherwise
• I2C_write(pSlave, regaddr, pData, bytes)
  • pSlave is a pointer to the slave struct to write to
  • regaddr is the start address to write to
  • pData is a pointer to the block of datas to write to slave
  • bytes number of bytes to write to slave
  • returns true if write is ok, false otherwise

Examples included:

following examples should work with any I2C EEPROM/FRAM with address 0x50 (yet function to get Chip ID are device dependant (and will probably only work on FUJITSU devices))

• ci2c_master_write.ino: Write some bytes to FRAM and compare them with what's read afterwards
• ci2c_master_read.ino: Read some bytes in FRAM
• ci2c_advanced.ino: Redirecting slave write & read functions (to custom functions following typedef)

Doxygen doc can be generated for the library using doxyfile

Links:

Feel free to share your thoughts @ xgarmanboziax@gmail.com about:

• issues encountered
• optimisations
• improvements & new functionalities

cI2C

• https://github.com/SMFSW/cI2C
• https://bitbucket.org/SMFSW/ci2c

WireWrapper

• https://github.com/SMFSW/WireWrapper
• https://bitbucket.org/SMFSW/wirewrapper