Integration Guide

Integration Guide 17
Chapter 4
Software Interface
Communication Protocol
The engine provides a bidirectional control interface for the communication
with the integrating platform based on the I
2
C communication. This is a
master/slave and host-initiated command/response type of protocol, and
the engine always acts as a slave.
It does not support unsolicited responses, meaning
that all transactions that
involve sending a command and receiving a response are always initiated by
the host system.
The time needed for execution depends on the command sent. If the engine
do
es not respond when requested by the host, it is possible that the com-
mand is still being processed. In this cas
e, the master will be forced into a
wait state until the slave is ready.
The maximum waiting time between receiving a command and the response
r
equest is 1 second. After this time a system timeout occurs and the engine
will reset.
Command Format
Commands sent via I
2
C from host (master) to engine (slave) should have the
following format:
Start bit Address Command
(hex code)
Command
Parameters
…
Checksum Stop bit
I
2
C Element
Description
Start bit:
Start bit as I
2
C standard specification.
Address:
Target slave address includes device address plus write option
(0x00).
For the engine, slave address is 0x5C (or 0xB8 after shifting to
7bit MSB).
Command:
See list of possible command codes for DE2011 in I2C Com-
mand Codes, starting on page 19
or Table 5 on page 19 .