Equinox Systems GEMINI Podręcznik Użytkownika Pobierz pdf (Strona 32)

User Guide V1.10

Overview

The Gemini programmer has been designed to support most common 8051 target system

RESET circuit scenarios. The timings used to enter and exit ‘Serial Programming Mode’ are

user-programmable using the <Options><Target Settings> dialogue box. This dialogue allows

the RESET polarity, hold time and release time to be altered. The characteristics of the Vpp

generator can also be adjusted within this menu.

RESET Polarity

An 8051 microcontroller requires an ‘Active

HIGH’ reset signal. i.e. to reset the device,

the programmer must assert the RESET pin

HIGH. The Gemini programmer features

user-selectable RESET polarity which caters

for both standard C/R RESET circuits and

also more complicated RESET circuits which

may require an ‘Active LOW’ signal.

PROG_ACTIVE Polarity

The PROG_ACTIVE line can be used to warn

the target microcontroller that the RESET pin

is about to be asserted. If an LED on the

target system is connected to the

PROG_ACTIVE line of the programmer, the

polarity should be set to ‘Active LOW’. The

LED will illuminate when the programmer

asserts the PROG_ACTIVE line at the start of

the programming sequence.

Connect to

µC RESET

circuit

RESET

Vcc

C/R Network Active HIGH

Watchdog IC Check relevant data sheet

RESET circuit Reset Polarity

Target Settings continued

PROG_ACTIVE

Vcc

Figure 19

Figure 20

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Equinox Systems GEMINI Podręcznik Użytkownika Strona 32