RTEMS BBB D-CAN Development Quick Reference

quick commands

Convert it into a bootable U-Boot image:

arm-rtems7-objcopy hello_dcan.exe \
  -O binary app.bin

gzip -9 app.bin


mkimage -A arm -O linux -T kernel -a 0x80000000 -e 0x80000000 -n RTEMS -d app.bin.gz rtems-app.img

In U-Boot:
BBB U-Boot configuration:

setenv ipaddr 192.168.5.4
setenv serverip 192.168.5.1

Transfer files:

tftpboot 0x80800000 rtems-app.img

tftpboot 0x88000000 am335x-boneblack.dtb

Run:

bootm 0x80800000 - 0x88000000

1. Build Workflow

Build RTEMS application

Inside repo:

cd ~/development/app/rtems-bbb-dcan

Build:

./waf

2. When to Run Configure

First time only

Run configure when:

  • first build
  • BSP changes
  • RTEMS toolchain changes
  • build directory deleted
  • configure options changed
./waf configure \
  --rtems=$HOME/development/rtems/7 \
  --rtems-tools=$HOME/development/rtems/7 \
  --rtems-bsp=arm/beagleboneblack

Normally

After source code changes:

./waf

No need to reconfigure.

3. Generated Files

After build:

build/arm-rtems7-beagleboneblack/hello_dcan.exe

4. Generate Bootable RTEMS Image

objcopy

arm-rtems7-objcopy \
  build/arm-rtems7-beagleboneblack/hello_dcan.exe \
  -O binary \
  app.bin

gzip

gzip -9 -f app.bin

Generates:

app.bin.gz

mkimage

mkimage \
  -A arm \
  -O linux \
  -T kernel \
  -a 0x80000000 \
  -e 0x80000000 \
  -n RTEMS \
  -d app.bin.gz \
  rtems-app-dcantest.img

5. TFTP Workflow

TFTP working directory

mkdir ~/tftpboot

macOS TFTP export directory

/private/tftpboot

sudo ln -sf ~/tftpboot/rtems-app-dcantest.img \
  /private/tftpboot/rtems-app-dcantest.img

sudo ln -sf ~/tftpboot/am335x-boneblack.dtb \
  /private/tftpboot/am335x-boneblack.dtb

Only needed once.

Copy updated image

After rebuild:

cp rtems-app-dcantest.img ~/tftpboot/

6. Start TFTP Server on macOS

Start

sudo launchctl load -F \
/System/Library/LaunchDaemons/tftp.plist

Stop

sudo launchctl unload \
/System/Library/LaunchDaemons/tftp.plist

Check status

sudo launchctl list | grep tftp

7. BBB U-Boot Network Setup

Configure BBB IP

setenv ethact ethernet@4a100000
setenv ipaddr 192.168.5.4
setenv serverip 192.168.5.1

Test connection

ping 192.168.5.1

Expected:

host 192.168.5.1 is alive

8. TFTP Download on BBB

Download RTEMS image

tftpboot 0x80800000 rtems-app-dcantest.img

Download DTB

tftpboot 0x88000000 am335x-boneblack.dtb

9. Boot RTEMS

bootm 0x80800000 - 0x88000000

10. Serial Console

Find serial device

ls /dev/cu.*

screen without logging

screen /dev/cu.usbserial-XXXXX 115200

screen with logging

TERM=xterm screen -L /dev/cu.usbserial-XXXXX 115200

Creates:

screenlog.0

11. Exit screen Properly

Ctrl-A
then k
then y

12. Kill Stuck screen Sessions

Find process

lsof /dev/cu.usbserial-XXXXX

Kill process

kill -9 <PID>

or:

pkill screen

13. Useful Git Commands

Check changes

git status

Add files

git add .

Commit

git commit -m "message"

Push

git push

14. .gitignore Recommended

/build
/build-*
doc
/*.ini
.lock*
*.pyc
.waf*

*.o
*.a
*.exe
*.bin
*.img
*.map
*.gz

15. Current Development Flow

Modify source code
    ↓
./waf
    ↓
objcopy
    ↓
gzip
    ↓
mkimage
    ↓
copy image to ~/tftpboot
    ↓
BBB tftpboot
    ↓
bootm
    ↓
observe UART logs

16. Current Driver Development Stages

Stage 1
RTEMS boot + D-CAN base address test
[Completed]

Stage 2
Enable DCAN clock

Stage 3
Read DCAN_CTL / DCAN_ES safely

Stage 4
Initialize D-CAN controller

Stage 5
Transmit CAN frame

Stage 6
Linux candump receives frame

Stage 7
Receive CAN frame on BBB

Stage 8
Interrupt handling

Stage 9
RTEMS CAN framework integration
/dev/can0