EME66xx

Hardware Description

Copyright © 2005, EM Microelectronic-Marin SA

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1.3.

Rear Panel

The V I/O adjustment allows the user to change the output drive level and input switching level of the V66xx

emulator. Thus, if it is required that the emulator operate in a system where the supply voltage is 0 to 3 volts,

then the inputs and outputs can be easily configured for this. The input switching level is CMOS compatible and

is around 0.5Vdd. So if V I/O is set to 3v then when input a Port will change from a logic 0 to a logic 1 at about

1.5V. In output mode a logic 0 will be approximately 0V and a logic 1 will be at approximately 3.0V.

In order to set V I/O it is necessary to do the following. Set an output line to drive a logic 1, e.g.

PortB-1. Then connect a voltmeter between PortB-1 and Ground (emulator side), turning the V I/O with a pot

trimmer will cause the output on the port pin to change, until the required level is obtained. It is possible to vary

the output drive between 1.5V and 5.5V.

Adjustment of the LCD drive levels are also possible using the VLCD trimmer pot. The output levels can be set

using a similar method to that outlined above, i.e. by setting a particular LCD column line high and measuring

with a voltmeter. The VLCD level can also be changed dynamically such that when display data is being

updated and the emulator is in RUN mode, it is possible to vary VLCD and observe what is happening to the

contrast on the display.

The POWER supply of the emulator is 12V DC/1A

1 2 3 4 5 6 7 8

1 2 3 4 5 6 7 8

V I/O

VLCD

S3

S4

RS-232

POWER