Problem:
Programming fails. Target AVR chip cannot enter programming
mode.
Probable causes and solutions
:
ISP frequency might be too high. Set the ISP frequency to well below
¼ of target MCU clock. Please note that the AVR MCU clock depends
on its fuses configuration.
Target power might not be stable enough or supply voltage might be
too low. Check your target board circuit. Ensure that the used AVR
chip specifications match your supply voltage.
Target power supply VCC might not be connected to pin 2 of
ICSP6/10. Check your target board circuit.
The target AVR MCU might have fuses programmed for disabling SPI
ISP or selecting another programming method. In such case you'll
need a High Voltage Parallel programmer to unlock the chip.
The reset line cannot be pulled low by the programmer. Check your
schematic and ensure that only a weak pull-up (and possibly a
small capacitor) are connected to RESET. Otherwise, if the pull-up
is too small or there is another output driving RESET, the
programmer won't be able to pull it down.
Another circuit is driving the ISP lines (MISO, MOSI, SCK or RESET)
resulting in a contention with the programmer. The solution is to
remove all such circuits (LEDs, RS232 drivers, resistors below 2k,
etc) from the four ISP lines during programming. AVR-ISP500 is
more susceptible to this kind of fault than other programmers on
the market because it has 560 ohm resistors in series with all its
outputs. This protects both the target MCU and the target board
circuit.
ELECTRICAL CHARACTERISTICS:
Symb
ol
Description
Condition
Min
Typ
Max
Uni
ts
V
TARG
Target Supply Voltage.
1.8
5.5
V
F
ISP
ISP Frequency on SCK
SPI pin.
5
2000 kHz
V
CC
Programmer Power
Supply Voltage.
4.6
5.4
V
I
CC
Programmer Power
Supply Current.
Idle
25
mA
Programming with AvrStudio,
V
TARG
=1.8V, F
ISP
=2MHz
30
mA
Time for a full
programming and
verification of
ATmega128 (128k
FLASH + 4k
FUSES + LOCK +
Signature check)
Programming with AvrStudio,
V
TARG
=5V, F
ISP
=2MHz
60
s
Time for a FLASH
programming and
verification of
ATmega128 (128k
FLASH)
Programming with AvrStudio,
V
TARG
=5V, F
ISP
=2MHz
25
s
