On May 12, 2025, at 13:01, Jody - K3JZD via groups.io <k3jzd.jody@...> wrote:

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Note - This is a follow up to my 29APR25 Posting, which almost got me there.? Some of the background that is that original posting may be of interest as it is not repeated here.

Goal

Make my zBITX usable for manual Straight Key CW Mode and manual Iambic Paddle CW Mode.? At any speed.

Approach

Fix it in software.?? Work within the confines of the existing zBITX and sBitx software.? In other words, apply band-aids, not do a major rewrite.

Solution

The solution was achieved by modifying just the sbitx_gtk.c file, which is a bridge between the underlying sBitx software and the zBITX software/hardware.? My solution was to change the two CW input pins (Dit & Dah) to use Interrupts (IRQs), add IRQ handlers, and then modify the ui_tick() function.

The ui_tick() function is a very busy function that, among many other things, calls the existing sBitx function that looks at the Ptt(Dit) and Dah hardware inputs. The ui_tick() function is triggered periodically by a hardware clock.? The ui_tick() function runs nearly every millisecond.? But, if the ui_tick() function has not completed all of the processing from the previous clocked trigger, that new trigger is not acted on.? So, it is not deterministic.

What was happening was that the ui_tick() process was frequently busy doing something else that took some time to complete whenever it needed to be processing a manual CW key-down occurrences in real time.?? Thus, it had a very poor and unpredictable response, and would not support rhythmic manual CW keying ?

My solution was to:

1.????? Have my Ptt(Dit) and Dah IRQ handlers immediately make the initial call to the existing sBitx function that looks at the Ptt(Dit) and Dah hardware inputs. ?If that existing function (and it¡¯s cast of supporting functions) finds a key down situation, the device is then put into Transmit Mode (the? in_tx? variable is set to True).

2.????? Move the call to the to the existing sBitx function that looks at the Ptt(Dit) and Dah hardware inputs to the very top of the ui_tick() function.? Right after making that call to check for CW activity, I then test the state of the ??in_tx ??variable.? If the? in_tx ?variable is True, then I exit out of the ui_tick() function right away so that I am not getting bogged down by processing anything else in that function.

3.????? Modify the ui_tick() function to test the state of the ?in_tx ?variable after each of the other various tasks that it does. ?If the? in_tx ?variable is True, then I exit out of the ui_tick() function right away so that I am not getting bogged down by processing anything else in that function.? (These additional exits were added because ui_tick() could already be doing something whenever the key down IRQ occurs. ?My multiple test and exit strategy gets me out of the ui_tick() function cleanly, as soon as it is practical to do so.

Result

My zBITX is now quite responsive to manual CW.? With a Straight Key and with Iambic Paddles.? It is Semi-QSK, not Full QSK.? I use a 750ms Semi-QSK Tail-Timer (this is the ¡®Delay¡¯, which is user adjustable from the zBITX GUI ¡®Set¡¯ selection). ?This tail timing suits my operating style.? Whenever the device is sending CW, the GUIs are no longer being updated. ?And the knob is disabled.

Giving up the GUI activity was the price I paid to make the device responsive to manual CW without doing a total software rewrite.? Because ?ui_tick() ?may already be executing some task that happens to be updating the screen during each initial Receive to Transmit switchover, you will occasionally see something ¡®blip¡¯ on the display during the Receive to Transmit switchovers.? Then the display will become static.

Implementing This Change

This is not an official zBITX release.? It is not in the zBITX github repository.? It is only here, in the sbitx_gtk.c file that I have attached to this posting.? ??If you are willing to rebuild your sbitx executable, which lives in your zBITX ??/home/pi/sbitx ??subdirectory, you can try out my solution:

1.????? Save the existing /home/pi/sbitx/sbitx_gtk.c file to a safe place.

2.????? Put my sbitx_gtk.c? file into your /home/pi/sbitx subdirectory.

3.????? From the command line. Execute ??./build??? ?Expect no errors.

4.????? Verify that you have a sbitx executable in your/home/pi/sbitx subdirectory.? It should be around 1.1 gb in size (I would occasionally get a zero length sbitx file).

5.????? Reboot your zBITX?? Plug in your Straight Key or Paddles.? You should now be good to go with manual CW.

Caveat

This is not an official zBITX release.? I am not setup for using SSB, AM, FT8, or any other mode with my zBITX.? ?While I do not see where my changes to the sbitx_gtk.c file to make manual CW usable will have any impact on these other modes, I have not tested any of them.

Going Forward

Perhaps Ashhar Farhan, zBITX developer, will consider my changes to allow manual CW at any speed to be usable on his zBITX, and perhaps will implement them (or some other solution) in a future official zBITX firmware release.? All of the changes that I made to my sbitx_gtk.c? file are identified with a ¡®k3jzd¡¯ comment.

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I am considering this resolved.? It meets my needs.? Look for you on the air (on CW). ???

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72,

Jody ¨C K3JZD

<sbitx_gtk.c>

On May 11, 2025, at 00:30, Gerald Sherman via groups.io <ve4gks@...> wrote:

One thing that might be worthwhile is to offer the V4 with different Pis, depending on the amount of RAM (2, 4, or 8 Gb) individual users desire. I realize this option would have to be reflected in the pricing. I would be willing to pay more for more memory.