8
•
Observe on the computer that the following is received from the interface:
91 12
and
92 04 xx.
This is the ‘mode of operation’ report. $91 indicates that the message is a ‘board status
report’ with one byte to follow. The $12 indicates the interface is up and running at idle
awaiting a mode switch command. The $92 $04 $xx is the firmware version report, where
‘xx’ is the firmware version. Refer to the “Master Commands and Responses” document for
complete and up-to-date information.
Note:
The AVT Controller software only displays and accepts hex digits, no dollar signs.
•
At this point the AVT-718 hardware is operational.
3. Interface Hardware
The following sections provide a brief description of the hardware implementation of the AVT-718.
A block diagram of the AVT-718 Multiple Interface is shown in Figure 1.
Included on the block diagram are all signal assignments and pin numbers for JP1 and P3.
3.1 Introduction
The AVT-718 provides an isolated electrical interface between the control computer and the
connected vehicle network. The AVT-718 Interface can be connected directly to a vehicle and
derives its operating power from the vehicle. The serial interface to the host computer is electrically
isolated from the vehicle electrical and electronic systems. This is done to prevent damage to the
host computer due to spikes or surges from the vehicle electrical system. It is not recommended that
the control computer be connected directly to the vehicle electrical system.
The AVT-718 Multiple Interface performs the necessary data and protocol conversion functions as
well as many other functions that can be enabled or disabled by the user to meet specific application
needs.
3.2 Overview
The hardware is structured around a central microcontroller, including on-chip peripherals. The
microcontroller utilizes several off-chip peripheral devices: FLASH memory; RAM; FIFO’s;
serial communications controller (SCC); CAN controller; J1850 VPW DLC device; J1850 PWM
HBCC device; and a free running 24-bit microsecond clock.
Also included in the hardware are transceivers for the various network interfaces. These may be
unique devices or implementations using discrete components.
3.3 Microcontroller
The heart of the AVT-718 Multiple Interface is the Motorola 68332 microcontroller which contains
a CPU32 core. The microcontroller contains 2 Kbytes of on-board RAM as well as a number of
peripheral functions (chip select, SCI, SPI, TPU, etc.).
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
