AVR debugger

This post shows some possible debuggers for the ATMEL AVR MCU. Due to a more and more difficult handling with the debug server AVARICE under Linux the subject is no longer pursued.

Because it's hard to find a serial interface (RS232) on todays PC's the Olimex-Debugger must be connected with a serial to USB adapter like the PL2303 to a PC.

The Linux kernel should load the module usbserial and have an udev device entry /dev/ttyUSBx created.
A new udev rule must be created:

~# vi /etc/udev/rules.d/z60_olimex.rules

The new rule should add a link from /dev/avrjtag to /dev/usbx while detecting the PL2303. Then the Olimex debugger is accessible under /dev/avrjtag.

SUBSYSTEM=="tty", KERNEL=="ttyUSB*", ATTRS{idVendor}=="067b", ATTRS{idProduct}=="2303"  SYMLINK+="avrjtag"

~# lsusb
.............
Bus 004 Device 003: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port
.............

The Olimex JTAG debugger can be used both to flash or debug the ATMEL AVR MCU.

The debugger is similar to an Atmel JTAG ICE MKI. It is also an equivalent and cheap replacement for the Olimex JTAG debugger. The device is detected as a simple “USB to serial” adapter on /dev/ttyUSBx. The entry in the udev rules is according to the rules of the Olimex debugger:

~# vi /etc/udev/rules.d/z60_jtagicemki.rules

The new rule should add a link from /dev/avrjtagicemki to /dev/usbx while detecting the debugger. The JTAG ICE MKI debugger is then accessible under /dev/avrjtagicemki.

SUBSYSTEM=="tty", KERNEL=="ttyUSB*", ATTRS{idVendor}=="1a86", ATTRS{idProduct}=="7523"  SYMLINK+="avrjtagicemki"

~# lsusb
.............
Bus 007 Device 004: ID 1a86:7523 QinHeng Electronics HL-340 USB-Serial adapter
.............

The JTAG ICE MKI debugger can be used both to flash or debug the ATMEL AVR MCU.

The JTAGICE3 is more up-to-date than the devices describes before. It supports also the ATMEGA 644 MCU in contrast to the Olimex or JTAG ICE MKI.

When the device is connect to the PC's USB port, it appears as /dev/usb/hiddev0. For having a distinct name a udev rule must create a link:

~# vi /etc/udev/rules.d/z61_jtagice3.rules

ACTION=="add", SUBSYSTEM=="usb", ATTRS{idVendor}=="03eb", ATTRS{idProduct}=="2140"  SYMLINK+="avrjtagice3"
SUBSYSTEM=="usbmisc", KERNEL=="hiddev*", MODE="0664", GROUP="plugdev"

~# lsusb
.............
Bus 004 Device 005: ID 03eb:2140 Atmel Corp.
.............

The tool AVRDUDE can be used on your PC to program the MCU attached local by one of the debugger. In order to program flash of the ATMEGA by AVRDUDE with one of the debugger (/dev/avrjtag, /dev/avrjtagicemki or /dev/avrjtagice3) over the network from one PC to another, the device must be made transparent by the tool ser2net. The tool offers telnet or raw connections over TCP/IP to a local serial interface.
First install ser2net:

~# apt-get install ser2net

The matching config file /etc/ser2net.conf contains entries to make /dev/avrjtag available as raw interface with 115200 Baud on port 4244 in IP based network:

4244:raw:0:/dev/avrjtag:115200 8DATABITS NONE 1STOPBIT

On the client PC the connection with AVRDUDE to /dev/avrjtag on the server can be established by calling AVRDUDE with options -P net:<servername>:4244. In Eclipse there is an entry needed in properties of menu AVR → AVRDUDE, Tab Programmer → Edit, “Override Default Port (-P)”.

Calling AVRDUDE on command line:

guest:~$ avrdude -cjtagmkI -P/dev/avrjtag

AVARICE is a GDB-server which offers a AVR-GDB remote session over network.
Installation:

~# apt-get install avarice

AVARICE must be started as user in a shell. In this example it should listen on port 4242 for incoming GDB remote sessions. A JTAG-frequency of 250kHz is the default.
The MCU in our example is a ATMEGA16:

guest:~$ avarice -1 --ignore-intr -d -l -j /dev/avrjtag -P atmega16 :4242

guest:~$ avarice -1 --ignore-intr -d -l -j /dev/avrjtagicemki -P atmega16 :4242

guest:~$ avarice -4 -P atmega169 -d :4242

The last option is only possible with the latest version of avarice from the SVN repositories.

Because AVARICE refuses proper operation on a ATMEGA644, debugging is not possible. It seems the AVARICE development is orphaned. For a good working debug session ATMELStudio of Microchip is needed, but is running only on Windows systems.