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Implement debugWire programming support. Several limitations are

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imposed by debugWire itself, so effectively, only flash ROM can be
read and written.

Currently, the required changes to avrdude.conf.in are only present
for the ATtiny44.


git-svn-id: svn://svn.savannah.nongnu.org/avrdude/trunk/avrdude@688 81a1dc3b-b13d-400b-aceb-764788c761c2
This commit is contained in:
Joerg Wunsch
2006-11-20 23:23:37 +00:00
parent 432ee9035b
commit 9b9df3e773
9 changed files with 477 additions and 48 deletions
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34
avrdude.1
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@@ -112,10 +112,11 @@ supported on a serial port.
.Pp
Atmel's JTAG ICE (both mkI and mkII) is supported as well to up- or download memory
areas from/to an AVR target (no support for on-chip debugging).
For the JTAG ICE mkII, both JTAG and ISP mode are supported.
For the JTAG ICE mkII, JTAG, debugWire and ISP mode are supported.
See below for the limitations of debugWire.
.Pp
The AVR Dragon is supported in all modes (ISP, JTAG, HVSP, PP).
When used in JTAG mode, the AVR Dragon behaves similar to a
The AVR Dragon is supported in all modes (ISP, JTAG, HVSP, PP, debugWire).
When used in JTAG and debugWire mode, the AVR Dragon behaves similar to a
JTAG ICE mkII, so all device-specific comments for that device
will apply as well.
When used in ISP mode, the AVR Dragon behaves similar to an
@@ -710,6 +711,33 @@ ll.
10 MISO (from MCU)
18-25 GND
.TE
.Ss debugWire limitations
The debugWire protocol is Atmel's proprietary one-wire (plus ground)
protocol to allow an in-circuit emulation of the smaller AVR devices,
using the
.Ql /RESET
line.
DebugWire mode is initiated by activating the
.Ql DWEN
fuse, and then power-cycling the target.
While this mode is mainly intented for debugging/emulation, it
also offers limited programming capabilities.
Effectively, the only memory area that can be read or programmed
in this mode is the flash ROM.
It is also possible to read out the signature.
All other memory areas cannot be accessed.
There is no
.Em chip erase
functionality in debugWire mode; instead, while reprogramming the
flash ROM, each flash ROM page is erased right before updating it.
This is done transparently by the JTAG ICE mkII (or AVR Dragon).
The only way back from debugWire mode is to initiate a special
sequence of commands to the JTAG ICE mkII (or AVR Dragon), so the
debugWire mode will be temporarily disabled, and the target can
be accessed using normal ISP programming.
This sequence is automatically initiated by using the JTAG ICE mkII
or AVR Dragon in ISP mode, when they detect that ISP mode cannot be
entered.
.Sh FILES
.Bl -tag -offset indent -width /dev/ppi0XXX
.It Pa /dev/ppi0