Equinox Systems Micro-ISP IV Series User Manual page 22

Micro-ISP
Device Programming Guide continued
5 Setting of the 'SPI frequency'
The setting of the 'SPI frequency' also varies with the
target voltage. It may be necessary to change the 'SPI
frequency' (Fspi).
To alter the 'SPI frequency' select <Options><ISP
Settings>
Enter the recommended 'SPI frequency' -
see the 'Timing Characteristic Tables'.
These tables show the fastest programming speeds
achieved at Equinox Technologies on two different
target devices. The optimum timings for these and
other devices will vary. It may be necessary to
experiment with differing settings to achieve the
fastest times.
6 Setting the 'Target Reset Polarity'
Meridian automatically sets the polarity of the programmer RESET signal (PROG_RESET) to be
the correct default polarity for the target device being programmed. Some users may wish to
change the 'Target Reset Polarity' if the RESET circuit on the target system is inverted for
some reason.
7 Setting the 'ISP RESET Timing' parameters
The programmer outputs a sequence of pulses on the PROG_RESET, PROG_MOSI,
PROG_MISO, PROG_SCK1 and PROG_LED signal lines in order to force the target device into
'Serial Programming Mode'. The programmer effectively runs a statemachine where the
programmer I/O lines are set to certain states for periods of time as specified by the 'T1....T6'
timing parameters. The default settings are for a generic Capacitor/Resistor RESET circuit and
a target system operating at +5V.
For Atmel AVR, ATmega and ATtiny devices, the default timing parameters should operate
correctly for most target systems without any changes. However, the Atmel 89S
microcontroller family suffers from many problems in entering 'Serial Programming Mode'
correctly if the RESET circuit is changed from a C/R network. The choice of the correct RESET
circuit and relevant settings for the 'T1....T6' timing parameters is beyond the scope of this
manual. Further information is available in separate application notes to be found on the
Equinox Web Site.
IV User Manual V2.03
Series
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