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Mention -B in the error message

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One of possible problems of failed initialization is too hight frequency
of ISP clock. Mention using -B option as a possible solution.

Closes #1133
This commit is contained in:
Łukasz Stelmach
2022-10-20 17:34:21 +02:00
parent 9977f1ed12
commit c890ff90eb
2 changed files with 10 additions and 8 deletions
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13
src/doc/avrdude.texi
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@@ -3046,14 +3046,15 @@ See also: @url{http://www.libusb.org/ticket/6}
@item
Problem: after flashing a firmware that reduces the target's clock
speed (e.g. through the @code{CLKPR} register), further ISP connection
attempts fail.
attempts fail. Or a programmer cannot initialize communication with
a brand new chip.
Solution: Even though ISP starts with pulling @var{/RESET} low, the
target continues to run at the internal clock speed as defined by the
firmware running before. Therefore, the ISP clock speed must be
reduced appropriately (to less than 1/4 of the internal clock speed)
using the -B option before the ISP initialization sequence will
succeed.
target continues to run at the internal clock speed either as defined by
the firmware running before or as set by the factory. Therefore, the
ISP clock speed must be reduced appropriately (to less than 1/4 of the
internal clock speed) using the -B option before the ISP initialization
sequence will succeed.
As that slows down the entire subsequent ISP session, it might make
sense to just issue a @emph{chip erase} using the slow ISP clock