Equinox Systems GEMINI Podręcznik Użytkownika Pobierz pdf (Strona 40)

User Guide V1.10

The following target system requirements must be met for the Gemini-1 programmer to

reliably in-system program (ISP) a target microcontroller:

Target Oscillator

The ISP mode of these microcontrollers uses a ‘Boot Loader’ stored in the target

microcontroller. It follows, therefore, that the target microcontroller must be able to execute

the ‘Boot Loader’ firmware. The speed at which the ‘Boot Loader’ firmware is executed

depends on the target oscillator frequency.

To ensure the fastest and most reliable ISP operation, the target oscillator frequency should

be chosen to be the highest value possible within the specification of the device. It is not

necessary to choose a frequency which gives an exact ‘Baud rate’ as the ‘Boot Loader’ is

capable of auto-detecting most baud rates and compensating accordingly.

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.

Target System - ISP Design Requirements continued

PROG_ACTIVE

Vcc

Figure 27

1 2 ... 35 36 37 38 39 40 41 42 43 44 45 ... 57 58

Brak uwag

Equinox Systems GEMINI Podręcznik Użytkownika Strona 40