Hitachi H8/300H boards

You can use the GDB remote serial protocol to communicate with a Hitachi H8/300H board. You must first link your programs with the "stub" module `src/gdb/config/H8/stub.c'. This module manages the communication with GDB. See section `The GDB remote serial protocol' in Debugging with GDB, for more details. Note that the Hitachi LCEVB running CMON has the stub already built-in.

Use the special gdb command `device port' if you need to explicitly set the serial device. The default port is the first available port on your host. This is only necessary on Unix hosts, where it is typically something like `/dev/ttya'.

GDB has another special command to set the communications speed: `speed bps'.

The following sample session illustrates the steps needed to start a program under GDB control on an H8/300, using a DOS host. The example uses a sample H8 program called `t.x'. The procedure is the same for other Hitachi chips in the series.

First hook up your development board. In this example, we use a board attached to serial port COM2. Call GDB with the name of your program as the argument. GDB prompts you, as usual, with the prompt `(gdb)'. Use two special commands to begin your debugging session: `target hms' to specify cross-debugging to the Hitachi board, and the load command to download your program to the board. load displays the names of the program's sections, and a `*' for each 2K of data downloaded. (If you want to refresh GDB data on symbols or on the executable file without downloading, use the GDB commands file or symbol-file. These commands, and load itself, are described in section `Commands to specify files' in Debugging with GDB.)

C:\H8\TEST> gdb t.x
GDB is free software and you are welcome to distribute copies
 of it under certain conditions; type "show copying" to see 
 the conditions.
There is absolutely no warranty for GDB; type "show warranty" 
for details.
GDB 4.13-94q4, Copyright 1994 Free Software Foundation, Inc...
(gdb) target hms com1
Connected to remote H8/300 HMS system.
(gdb) load t.x
.text   : 0x8000 .. 0xabde ***********
.data   : 0xabde .. 0xad30 *
.stack  : 0xf000 .. 0xf014 *

At this point, you're ready to run or debug your program. From here on, you can use all the usual GDB commands. The break command sets breakpoints; the run command starts your program; print or x display data; the continue command resumes execution after stopping at a breakpoint. You can use the help command at any time to find out more about GDB commands.

Remember, however, that operating system facilities aren't available on your development board; for example, if your program hangs, you can't send an interrupt--but you can press the RESET switch!

Use the RESET button on the development board:

• to interrupt your program (don't use Ctrl-C on the DOS host--it has no way to pass an interrupt signal to the development board).
• to return to the GDB command prompt after your program finishes normally. The communications protocol provides no other way for GDB to detect program completion.

In either case, GDB sees the effect of a RESET on the development board as a "normal exit" of your program.