To set up these Emerson embedded boards it is important to understand first what these are PowerPC-based projects, using the MPC7457 CPU which uses a core with a generic FPU unit.
The reason why I bring this up as an interesting project is because the issue I run into with the 6500. These are boards that are inserted, generally, unto a chassis. Once inserted, the chassis is powered on and then the you can serial-connect to the specific board you want. In my case, I was not seeing anything booted at the time. So, what do you do? Well, you get the bootloader and the hardware manual from the manufacturer or from the OS company. In this case, WindRiver made the bootloader for this and the instructions indicated a few pins you had to change to allow some memory banks to be reasable and loaded at boot time.
This didnt work with the default settings. And this is where experience comes handy, which allows you to try things you otherwise wouldn’t date to. I moved the pins to exactly the opposite of what the instructions said. THis was dangarous as the process was copying memory from one bank no another, thus this could result in catastrophy and the need to send back the board back to the manufacturer to be fixed. It worked though!
When working with embedded systems, partners, manuals and all kinds of software, firmare and hardware, it is important to also trust your gut and your experience. I did not want to mention any specific details as this project had confidential agreements, but I thought it would be interesting to mention the experience I had 🙂
When working with embedded systems, partners, manuals and all kinds of software, firmare and hardware, it is important to also trust your gut and your experience. I did not want to mention any specific details as this project had confidential agreements, but I thought it would be interesting to mention the experience I had 🙂
Enable remote serial connection
This wasn’t all. I needed to enable remote access through serial connection. The board would be connected to a Linux host with a mini-serial to USB cable. In order to connect via serial connection to the board, we need to:
1) ssh to the host
2) Connect using a serial connection to the board through the right USB device. The USB connected with the board in this case was is /deb/ttyUSB0. Very easy information to get from a Linux host.
In order to connect to the USB, we need to make sure first that the user doing it belongs to the same group as the device. Let’s take a look at the device group:
[/home/victor] ssh serial-server
Last login: Wed Mar 19 13:46:30 2022
Load:
13:52:05 up 15 min, 1 user, load average: 0.00, 0.01, 0.02
[/home/victor] ls -l /dev/ttyUSB0
crw-rw---- 1 root uucp 188, 4 Mar 19 13:37 /dev/ttyUSB0
As we can see, the device belongs to group “uucp”. I need to make sure that my user (“victor” in this example), also belongs to the same group:
[/home/victor] groups
wheel engineers
As we can see, user victor does not belong to the same group as the device. This means that we will not be able to connect to the USB device. If we try, we will get the following error message:
[/home/victor] cu -l /dev/ttyUSB0 -s 9600
cu: open (/dev/ttyUSB0): Permission denied
cu: /dev/ttyUSB0: Line in use
Let’s then add the user victor to the group uucp. We need to be root for this:
[root ~]# usr/sbin/usermod -a -G uucp victor
Once we do this, we need to log out, and log back in as user victor. Then, let’s see if we are now joined to the same group:
[victor@serialb /home/victor] groups
wheel uucp engineers
Yes, we are! The final step is then connecting to the USB device that is connected to the serial port at the board:
[victor@serialb /home/victor] cu -l /dev/ttyUSB0 -s 9600
Connected.
We are connected! Now, we can go ahead and power-on the board. We should see the VxWorks kernel loading.
Enable remote power cycle
Lastly, I also needed to In order to enable the board to be power-cycled, we need to find first jumper JP12 in the board (very close to the power connection). This jumper allows you to bypass the power button on the board so that any time power is applied the board will be powered on. This should allow us to remotely power cycle the board from your power server. The default setting of this jumper is 2-3 which enables the power button. Setting this to 1-2 will bypass it.
