Evalu8r User Manual V2.00

12

An important difference between the Atmel 89C/89S and AVR microcontrollers is the polarity

of the RESET pin. The 89C/89S devices feature an ACTIVE HIGH Reset, where as the AVR

devices feature an ACTIVE LOW Reset. The Evalu8r module features user configurable RESET

polarity. It is necessary to change only two jumper settings as detailed below to support

either ACTIVE HIGH or ACTIVE LOW RESET polarity.

RESET Configurations

C7

10

µF

Vcc

R4

10K

R11

120

S6

RESET

8051

Con 8

Pin 10

EXTERNAL

RESET

C10

10

µF

Vcc

R10

10K

R11

120

S6

RESET

AVR

Con 8

Pin 10

EXTERNAL

RESET

Active High RESET Function

Active Low RESET Function

Figure 29

Figure 30

Suitable for 8051 microcontroller family

e.g. 87C/89C/89S devices

Suitable for:

All AVR microcontrollers

Link 3

Link 4

1-2

1-2

Link 3

Link 4

2-3

2-3

Please note the use of a C/R RESET circuit

will not prevent corruption of the on-chip

AVR EEPROM

Figure 31

Figure 32