Image retrieval program crashing on still image Pi

[sten]

Short version:

We can no longer pull images from the still image payload using the ground station laptop (we used to be able to!). I have plugged in a monitor and keyboard to the Pi on the still image payload to try and figure out the issue. I understand that the Pi is supposed to run a program on start-up that waits to hear from the ground station laptop and then sends the image over the modem. I can start this program manually, but every time the ground station laptop requests an image, the program on the Pi crashes. I will get a screenshot of this error message later this afternoon while we are working on it again.


Long version:

Following the instructions, we could retrieve images from the still image payload and view them on the ground station laptop. However, this did not work 100% of the time. Sometimes we could not save an image and the system behaved as if the modems were not connected even though we were getting solid green lights on both modems and hadn't changed anything from the working setup. It seemed that after switching the still image computer off and then back on (using the keys), we could then retrieve pictures again (sometimes multiple hard restarts were required). However, it seems like doing this endangers the SD card and if I understand correctly, we should be shutting the still image computer down by ssh-ing in over the adhoc wireless network and sending the 'sudo shutodwn -h now command'.

To try and get to 100% retrieval rate, we followed some advice on the forum here and disabled ssh over serial. This didn't change the success rate and then we could no longer ssh via Putty and shut down the computer properly. After restoring ssh over serial by plugging the still image Pi into a monitor, we now have a 0% retrieval rate of images. The modem lights are both solid green, but we can not retrieve an image using the ground station laptop and are met with a flurry of "Waiting For Acknowledge". So either we messed something up by disabling ssh over serial and re-enabling it, or something else is going on. As mentioned in the "short version" above, it seems that when we try and retrieve an image from the ground station laptop, the program on the Pi crashes (error message coming soon!).

Thanks for any help you can offer on this one.

Sten

[undballooning]

The exact same thing is happening to us- none of the fixes work. We were having spotty success before, but now we are also getting a 0% retrieval rate.

[sten]

So we think we may have figured this out. We were able to retrieve a still image 3 times in a row.

It turns out we were shooting ourselves in the foot in a couple of areas:

• Before doing anything, verify the modems are connected with the 3DRRadio application. Sometimes we thought the modems were connected because the green lights were solid, but one time this application indicated that they were not. I think I saw somewhere on the forum mention that they may only blink once every 30 seconds or so. When both modems are on, start the application. Change the COM port to the proper port and change the Baud to 38400. Then hit "Load Settings". If the local RFD and remote RFD pop up, you are good to go.
  
• Disable ssh over serial in raspi-config (not ssh, ssh over serial). This is something that David has said many times and something we thought we were doing correctly. However, it seems possible that during a hard reset (turning key without shutdown), the setting reverts back? We have not confirmed this, but we have had to go through the raspi-config to disable ssh over serial multiple times.
  
• Perhaps don't be logged on to Pi while trying to retrieve images? In my debugging process, the program on the Pi that runs at startup would crash if I was logged in on the Pi while trying to retrieve images from the ground station computer. I have not confirmed this, but if you are having issues, maybe make sure you do not log in to the Pi while trying to retrieve images from the ground station.

The big issue, however, seemed to be the first bullet. Definitely verify the connection using the 3DRRadio application before trying to do anything.

I'll post again if we run in to issues, but we *think* everything is working fine.

[David MSGC]

Stens last post is 100% correct. If the led on the modem blinks even once over a long period of time you have to get it to be solid and restart the program on the ground station computer. If ssh over serial is enabled the RFD program on the either side will not be able to communicate with one another, none of it will work but it will still keep taking pictures and you will not be able to communicate with it. If you log into the pi and manually start the program it may or may not work, you essentially have two instances of the same program running and sharing the serial port, there is no way for the two programs to coordinate serial traffic.If you want to manually run the program and use a monitor to watch the output you have to stop the program that starts at startup.
Make sure radios are paired, no blinking green LED for at least 30 seconds, then start the program on the ground station side.
Never enable ssh over serial.
If you want to run the program manually you can only have one instance of the program running at a time, either comment out the line in crontab and reboot, or find the process id of the program with "top" and kill it with "sudo kill xxx" xxx is the process ID.