AN2038 Datasheet, PDF (1/23 Pages) STMicroelectronics – I2C emulation with ST7MC in slave mode

AN2038
Application note
I2C emulation with ST7MC in slave mode
1
Introduction
This application note describes how to emulate I2C communication using an ST7MC as
slave device. Since there is no dedicated I2C peripheral in the ST7MC microcontroller, the
protocol is emulated using the SPI peripheral. This peripheral is common to different ST7
products so the software presented can be easily adapted to run in other ST7
microcontrollers. In this document, the hardware and software description refers to the
ST7MC microcontroller for motor control applications. See Section 7: Reference and related
materials to get more information about standard motor control libraries. Section 4: Software
modifications describes the modification you need to make to implement I2C communication
in the current standard libraries for specific types of motor.
Section 3: Hardware modifications describes the required modifications to the ST7MC
Starter Kit board (Softec AK-ST7FMC) for implementing I2C communication.
The two modules presented in this application note are C modules (.h and .c file) developed
to be compiled with Cosmic compiler v.4.5b (see www.cosmic-software.com for information
and free download) and used in Softec STVD7 v.3.10 Integrated Development Environment
(see www.softecmicro.com for information and free download). The first module, called I2C
module implements the low level I2C protocol, the second module, called ProtoSup
module is an example of a customized protocol based on I2C emulation. This protocol
implements a Frame of Communication that allows the master to send a set of typical
commands for a motor control application.
You should have a basic knowledge of C programming, motor control drives and basics of
I2C protocol in order to use this module. In-depth know-how of ST7MC functions is only
required for customizing existing modules or when adding new modules to develop your own
application.
June 2006
Rev 1
1/23
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