Interfaces

Having discussed about Embedded Robotic Controllers in my previous post its now time to discuss about the Interfaces.

A number of interfaces are available on most embedded systems. These are
digital inputs, digital outputs, and analog inputs. Analog outputs are not
always required and would also need additional amplifiers to drive any actuators.
Instead, DC motors are usually driven by using a digital output line and a
pulsing technique called “pulse width modulation” (PWM).





The Motorola M68332 microcontroller already provides a number of
digital I/O lines, grouped together in ports. We are utilizing these CPU ports as can be seen in IMAGE below.



But it also provide additional digital I/O pins through latches.Most important is the M68332’s TPU. This is basically a second CPU integrated on the same chip, but specialized to timing tasks. It simplifies tremendously many time-related functions, like periodic signal generation or pulse counting, which are frequently required for robotics applications.

First 2 pictures above shows the EyeCon board with all its components and interface connections from the front and back. Our design objective was to make the construction of a robot around the EyeCon as simple as possible. Most interface connectors allow direct plug-in of hardware components. No adapters or special cables are required to plug servos, DC motors, or PSD sensors into the EyeCon. Only the HDT software needs to be updated by simply downloading the new configuration from a PC; then each user program can access the new hardware.

The parallel port and the three serial ports are standard ports and can be used to link to a host system, other controllers, or complex sensors/actuators.Serial port 1 operates at V24 level, while the other two serial ports operate at TTL level.
The Motorola background debugger (BDM) is a special feature of the M68332 controller. Additional circuitry is included in the EyeCon, so only a cable is required to activate the BDM from a host PC. The BDM can be used to debug an assembly program using breakpoints, single step, and memory or register display. It can also be used to initialize the flash-ROM if a new chip is inserted or the operating system has been wiped by accident.



At The University of Western Australia, they are using a stand-alone, boxed version of the EyeCon controller for lab experiments in the Embedded Systems course. They are used for the first block of lab experiments until we switch to the EyeBot Labcars.