Thanks Alan, I’ll measure the xtal socket and see what’s on each pin. I’ll have to be careful to put the voltage pin on a socket with 5v regulated voltage.
73 Tom

开云体育

Somebody asked me how I access the QMX terminal settings if the radio is connected to a headless Raspberry Pi that I can connect to only with a text based ssh connection (or through a browser window with ttyd). Without a graphical desktop system, tools like Putty don't work. So, here are some notes on using GNU screen for this.

GNU screen is a text based terminal multiplexer that is widely available on Linux machines. If it isn't installed on your raspberry pi, you can install it with 'sudo apt install screen'. I often use it so that, after I connect to the pi using ssh, I can create multiple windows (tabs) that I can switch between to run multiple programs. If my ssh network connection to the pi is closed, programs running in screen windows (like ardopcf or pat) continue to run, and I can reconnect to them later. See 'man screen' or various online articles and videos for a description of this normal usage.

A less well know use of screen is to connect to a serial device with it. So, if the QMX is connected to the pi with a USB cord, so that it appears as virtual serial port '/dev/ttyACM0', you can open the QMX terminal using the command: 'screen /dev/ttyACM0'.

Just like when connecting with Putty, this displays a blank black screen until you press <Enter>, and then you will see the QMX terminal menus. Keyboard input including arrow keys should then work as expected.

However, there are two things that are different than when using a program like Putty. First, Ctrl-Q, which Hans chose to use to back out of various sub-menus and screens, does not work when using GNU screen. To send Ctrl-Q to the QMX, you need to type Ctrl-a and then q. Second, to close a screen window, usually after selecting the 'Exit terminal' command in the QMX menus, type Ctrl-a and then k. This will prompt you with 'Really kill this window [y/n]', so type y.

If you are already running screen, perhaps with multiple windows, you can also open a new window to connect to the QMX by typing Ctrl-a and then typing ':screen /dev/ttyACM0' (without the quotes) and pressing <Enter>. Once you type the colon (:), it and the remainder of this command will appear in the lower left corner of the window until you press<Enter>. When you are done, typing Ctrl-a and then k will close this window but not any other screen windows that you have created.

Hopefully some of you will find these notes useful. Using the QMX terminal is even more important now with the changes in the new SSB beta firmware.

Peter LaRue
AI7YN

1. VDD = 4.5 V is higher than the rating and heavy stress for most of the IC connected to VDD. The controller, the heart of the QMX, is connected to VDD.
2. VDD = 4.5 V and a higher current looks like the zener diode D109 is in action. With regard to the characteristic the diode current could be 120 ... 160 mA and the power 540 ... 720 mW. This diode is rated 500 mW and may heat up to much from to much power. If this diode will break the resistance could go to a low value or a high value. For first case VDD would be lower and no problem for the controller and for the second case vice versa bringing more danger for the STM32 and others.

Also replug the front panel and look at the display connection and while it's out check for a tiny bridge or a whisker that may be in there. That will answer a lot of questions?

I'm wondering if you have a temperature-dependent issue that causes the 5V supply to get shorted to Vdd, pulling Vdd up and Vcc down.
Maybe also take a resistance measurement (with power off) between Vdd and Vcc.

When you said you could reproduce the problem by trying to attach the terminal, did it happen when you connected the cable, or when you hit enter in the terminal window to bring up the menu?