I2C interface modules for Cocotb

GitHub repository: https://github.com/alexforencich/cocotbext-i2c

Introduction

I2C simulation models for cocotb.

Installation

Installation from pip (release version, stable):

$ pip install cocotbext-i2c

Installation from git (latest development version, potentially unstable):

$ pip install https://github.com/alexforencich/cocotbext-i2c/archive/master.zip

Installation for active development:

$ git clone https://github.com/alexforencich/cocotbext-i2c
$ pip install -e cocotbext-i2c

Documentation and usage examples

See the tests directory, taxi, and verilog-i2c for complete testbenches using these modules.

I2C Master

The I2cMaster class can be used to issue read and write operations on an I2C bus.

Example:

from cocotbext.i2c import I2cMaster

i2c_master = I2cMaster(dut.sda_i, dut.sda_o, dut.scl_i, dut.scl_o, 400e3)

To issue I2C operations with an I2cMaster, call read() or write(). These are the preferred methods, as they will manage the bus state automatically. Lower-level methods must be called in the appropriate order. The read() and write() methods will leave the bus active, so call send_stop() to release the bus.

Constructor parameters:

• sda: serial data in/out
• sda_o: serial data output
• scl: clock in/out
• scl_o: clock output
• speed: nominal data rate in bits per second (default 400e3)

Attributes:

• speed: nominal data rate in bits per second

Methods

• write(addr, data): send data to device at address addr (blocking)
• read(addr, count): read count bytes from device at address addr (blocking)
• send_start(): send a start condition on the bus
• send_stop(): send a stop condition and release the bus
• send_byte(): send a byte on the bus
• recv_byte(): read a byte from the bus

I2C Device

The I2cDevice class emulates an I2C device. This class cannot be used directly, instead it should extended and the methods handle_start(), handle_write(), handle_read(), and handle_stop() implemented appropriately. See I2cMem for an example.

Constructor parameters:

• sda: serial data in/out
• sda_o: serial data output
• scl: clock in/out
• scl_o: clock output

I2C Memory

The I2cMemory class emulates a simple memory like an I2C EEPROM.

Example:

from cocotbext.i2c import I2cMemory

i2c_mem = I2cMemory(dut.sda_i, dut.sda_o, dut.scl_i, dut.scl_o, 0x50, 256)

The memory can then be read/written via I2C operations on the bus, with the first bytes written after a start bit setting the address, and subsequent reads/writes advancing the internal address and reading/writing the memory. The memory can also be accessed via read_mem() and write_mem().

Constructor parameters:

• sda: serial data in/out
• sda_o: serial data output
• scl: clock in/out
• scl_o: clock output
• addr: device address (default 0x50)
• size: size in bytes (default 256)

Methods

• read_mem(addr, count): read count bytes from memory, starting at addr
• write_mem(addr, data): write data to memory, starting at addr