Running an eCos threads demo on a GP4020 receiver

1.0: Overview

Here's how to run the "two threads demo" included in the ecos source. It's a great little demo, and will show you how the whole eCOS + application thing works. Here's what we're going to do:

1. Build eCOS configured for the GP4020 into a library (libtarget.a, in fact).
2. build the twothreads.c demo and link to the eCOS library.
3. Upload the file and run it on the GP4020 using gdb

This demo assumes you already have redboot running from the flash - see RedBootOnTheMG5001.

1.1: Build eCOS

• Once again, create a directory. I called it ecos_twothreads.
• In that directory, run the configtool.
• Choose Template from the Build menu.
• Choose GPS 4020 from the hardware drop down list. Then choose default from the Packages drop down.
• You shouldn't have to do much:
  • The eCOS HAL / ARM Architecture / GPS4020 evaluation board / Startup time (CYG_HAL_STARTUP option) should be set to RAM.
  • The eCOS HAL / ROM Monitor Support / Work with ROM monitor should be checked, and the value should be GDB_stubs.
  • Massa suggests turning on asserts and tracing, and I can't disagree: Under Infrastructure, check Asserts & Tracing and Use Asserts
• Choose Save from the File menu and save that file in the directory you made above. I called it ecos_default.ecc.
• Choose Build, Library and now the configtool will build you the eCOS library for GP4020 meant to run in RAM. The library can be found in ecos_twothreads/ecos_default_install/lib directory.

1.2: Build the Application and link with eCOS

• makes sure you're in the ecos directory from above, in my case ecos_twothreads.
• Get the .c file and the Makefile: cp /opt/ecos/ecos-2.0/examples/twothreads.c and cp /opt/ecos/ecos-2.0/examples/Makefile.
• Now the Makefile we just copied is a generic make file for all the examples and for all platforms. So we'll give make some settings specific to this demo: make twothreads INSTALL_DIR=ecos_default_install ECOS_COMMAND_PREFIX=arm-elf-
• You should get twothreads and twothreads.o.
• Now turn it into a Motorola S-record format: arm-elf-objcopy -O srec twothreads twothreads.srec
• And yes, although it's impossibly big, it will fit (since the SREC format is much larger than what's ending up in memory)
• And just for the heck of it, let's just give it a quick spin using redboot's go command, which knows the start address of the loaded code because of the last record in the SREC file:

RedBoot> load -v -m xmodem CEntry point: 0x20008040, address range: 0x20008000-0x2001c088 xyzModem - CRC mode, 1924(SOH)/0(STX)/0(CAN) packets, 1 retries RedBoot> go Entering twothreads' cyguserstart() function Beginning execution; thread data is 0 Beginning execution; thread data is 1 Thread 0: and now a delay of 239 clock ticks Thread 1: and now a delay of 230 clock ticks Thread 1: and now a delay of 221 clock ticks Thread 0: and now a delay of 214 clock ticks Thread 1: and now a delay of 224 clock ticks . . . . . . . . .

1.3: Using gdb

If you did use redboot to run the demo application, then reset your board so it's running redboot again. And make sure to exit minicom.

• From the same directory (ecos_twothreads), type arm-elf-gdb
• type set remotebaud 57600
• type target remote /dev/ttyS0
• type load twothreads
• type continue

And voila! You've got gdb up and running an eCOS application on the GP4020-based receiver. Now THAT'S cool.

Here's a transcript of the commands:

$ arm-elf-gdb GNU gdb 5.3 (eCosCentric) Copyright 2002 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or 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. This GDB was configured as "--host=i686-pc-linux-gnu --target=arm-elf". (gdb) set remotebaud 57600 (gdb) target remote /dev/ttyS0 Remote debugging using /dev/ttyS0 0x600033f4 in ?? () (gdb) load twothreads Loading section .romvectors, size 0x40 lma 0x20008000 Loading section .text, size 0x106d8 lma 0x20008040 Loading section .rodata, size 0x35f0 lma 0x20018718 Loading section .data, size 0x380 lma 0x2001bd08 Start address 0x20008040, load size 82056 Transfer rate: 36469 bits/sec, 299 bytes/write. (gdb) continue Continuing. Entering twothreads' cyguser_start() function Beginning execution; thread data is 0 Beginning execution; thread data is 1 Thread 0: and now a delay of 239 clock ticks Thread 1: and now a delay of 230 clock ticks [New Thread 1]

Program received signal SIGINT, Interrupt.
[Switching to Thread 1]
0x2000c934 in ?? ()
(gdb) continue
Continuing.
Thread 1: and now a delay of 221 clock ticks
Thread 0: and now a delay of 214 clock ticks
Thread 1: and now a delay of 224 clock ticks

Program received signal SIGINT, Interrupt.
0x2000c938 in ?? ()
(gdb) q
The program is running.  Exit anyway? (y or n) y
$