Re: boards and kits and stuff

On Thu, Mar 20, 2025 at 08:43 AM, Tom - AJ8X wrote:

and the receiver doesn't come on like it does if there's no display cable installed ...

I've tested this.? The T41 doesn't get to the setup routine when a long display cable is used.? It gets stuck trying to create the RA8875 object.

Re: boards and kits and stuff

#33121

On Thu, Mar 20, 2025 at 07:56 AM, Greg KF5N wrote:

The next step is to investigate boosting the Teensy's GPIO drive strength and bandwidth via software changes.

I'm just wondering if the current design gets all it can from the default driver setting.? My tests show that crosstalk is a problem on the display cable and that modifying the SPI signal order on it more than doubles the allowed cable length.? This requires hand wiring the display with the v12 board, which is impractical. I checked my wiring many times when I tested it before turning on the power.? And I was still worried I'd blow up the display. But this could be easily accommodated in a new board design with a small connector board at the display to reorder the signal properly.

?

The SPI traces on the Main board are also routed next to each other.? Rerouting them, if possible, could be another opportunity to reduce crosstalk and possibly simplify the overall design and avoid changing the software.

?

Just a few thoughts for consideration in a future board update. ?Perhaps the testing required for these makes them impractical though.? It's probably just easier to boost the signal strength and call it a day.

Re: boards and kits and stuff

#33120

... and the receiver doesn't come on like it does if there's no display cable installed ...

Re: boards and kits and stuff

#33119

I just made a 20' cable. It works fine for the front panel buttons, but when I install it for the display the screen doesn't come on. Is that useful information, or did everyone expect that?

Re: boards and kits and stuff

#33118

Hi Terrance-

?

The original V11 Main board design uses a driver IC for the SPI bus which drives the display.? Same for the original kits.? No one complained about display issues that I can recall.

There was some moderate noise from the display which is for the most part, overridden by atmospheric noise when you connect an antenna.? Some of that noise was due to inadequate bypassing on the QSD board.

I have designed a new Main board, with an improved layout and more bypassing/decoupling.? It uses the same SPI driver as the original.? Also I have a new QSD2 which has improved bypassing/decoupling.

The display performance is solid and any display related noise is inconsequential.

It's a good assumption that if the original display driver had been incorporated into the V12 Main board, no one would be complaining about bad display behavior or display related noise (V12 has EMI improvements).

?

The next step is to investigate boosting the Teensy's GPIO drive strength and bandwidth via software changes.? If that is successful, the driver IC (and buffer board) could possibly be eliminated without anyone

complaining about bad display behavior, and with V12s EMI improvements, display noise would probably be a non-issue as well.

?

--

73 Greg KF5N

Re: boards and kits and stuff

#33117

开云体育

Routing has already been optimized… with the 4-layer board.

?

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it:

?

Moderator: North American QRO Group at Groups.IO.

Moderator: Amateur Radio Builders Group at Groups.IO.

?

email:? bill@...

?

Show quoted text

From: [email protected] <[email protected]> On Behalf Of Terrance Robertson, KN6ZDE via groups.io
Sent: Thursday, March 20, 2025 9:23 AM
To: [email protected]
Subject: Re: [SoftwareControlledHamRadio] boards and kits and stuff

?

I'll try mine out with a very long cable as well.

?

Regarding future Main board designs, has routing the SPI traces to minimize crosstalk been considered?

?

Re: boards and kits and stuff

#33116

开云体育

Plugs DIRECTLY into the display connector on the MAIN board and sits OVER the MAIN BOARD like the picture below:

?

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it:

?

Moderator: North American QRO Group at Groups.IO.

Moderator: Amateur Radio Builders Group at Groups.IO.

?

email:? bill@...

?

Show quoted text

From: [email protected] <[email protected]> On Behalf Of Greg KF5N via groups.io
Sent: Wednesday, March 19, 2025 2:32 PM
To: [email protected]
Subject: Re: [SoftwareControlledHamRadio] boards and kits and stuff

?

Hi Bill-

?

Is your board placed at the display end?? It seems like it is more of a "buffer board" rather than a driver board, if so.
I'm trying to visualize why it works.

?

--

73 Greg KF5N

Re: boards and kits and stuff

#33115

I'll try mine out with a very long cable as well.

?

Regarding future Main board designs, has routing the SPI traces to minimize crosstalk been considered?

?

Re: boards and kits and stuff

#33114

开云体育

In your case, try out a LONG cable… say 3 feet and see if that works.? If it does, I’ll start mass-producing them… and possibly get Oliver to place the circuitry on a V12.7 main board for future builds.

?

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it:

?

Moderator: North American QRO Group at Groups.IO.

Moderator: Amateur Radio Builders Group at Groups.IO.

?

email:? bill@...

?

Show quoted text

From: [email protected] <[email protected]> On Behalf Of Albert Peter via groups.io
Sent: Thursday, March 20, 2025 4:33 AM
To: [email protected]
Subject: Re: [SoftwareControlledHamRadio] boards and kits and stuff

?

Bill,

My system is working and without freeze-ups, but I will try out your board.

Al

Re: boards and kits and stuff

#33113

Bill,

My system is working and without freeze-ups, but I will try out your board.

Al

Re: boards and kits and stuff

#33112

I believe that this is the "correct" solution.

Re: boards and kits and stuff

#33111

开云体育

I have both M and C parts, but it doesn’t seem to make a difference.

?

If there is a software fix for this, I really wonder why someone hasn’t done it.? There are posts all over the PRJC site about it yet no one has done a damn thing to fix it.

?

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it:

?

Moderator: North American QRO Group at Groups.IO.

Moderator: Amateur Radio Builders Group at Groups.IO.

?

email:? bill@...

?

Show quoted text

From: [email protected] <[email protected]> On Behalf Of Greg KF5N via groups.io
Sent: Wednesday, March 19, 2025 6:49 PM
To: [email protected]
Subject: Re: [SoftwareControlledHamRadio] boards and kits and stuff

?

I hope you got the M version.? The C version is only specified to 25 MHz.

?

Also, remember there is a potential software solution to boost the Teensy drivers.

That will require drilling into the device specification and writing some low level code.

The TeensyDuino does not provide support for the faster and more powerful modes the GPIO is apparently capable of.

?

--

73 Greg KF5N

Re: boards and kits and stuff

#33110

I hope you got the M version.? The C version is only specified to 25 MHz.

?

Also, remember there is a potential software solution to boost the Teensy drivers.

That will require drilling into the device specification and writing some low level code.

The TeensyDuino does not provide support for the faster and more powerful modes the GPIO is apparently capable of.

?

--

73 Greg KF5N

Re: boards and kits and stuff

#33109

I use these ferrite sleeves for ribbon cables. Seems to work FB.

Tim W4YN

Re: boards and kits and stuff

#33108

Another wacky, but successful solution is to hand wire the display with the SPI signals separated by the ground/power lines.? I used the following order successfully on an 8.5" cable:

?

1. SCLK (gray)

2. GND (white)

3. VCC (black)

4. CS (brown)

5. VCC (red)

6. MISO (orange)

7. GND (yellow)

8. MOSI (green)

?

The display and Main board have a few other ground connections that could be used to make this more robust, but I didn't try that after this worked with just the display dedicated connections.

Re: boards and kits and stuff

#33107

开云体育

Well, the ISO7241 is a specially designed SPI buss buffer/ isolator/ driver chip…, it plugs into the T41 display socket on the main board (close to the Teensy) and the display cable plugs into it.? We know that the problem with the display lines are the poor SPI line driver transistors on the Teensy.? This essentially puts a much higher power (lower impedance) driver/ buffer after, but close to those transistors…? PS thinks this was genius… I’m thinking it was more desperation in searching for and finding it.? ?Short J3 and leave U2 off if the display is 3.3V.? Leave J3 open and add U2 if its 5V.? Super simple.

?

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it:

?

Moderator: North American QRO Group at Groups.IO.

Moderator: Amateur Radio Builders Group at Groups.IO.

?

email:? bill@...

?

Show quoted text

From: [email protected] <[email protected]> On Behalf Of Greg KF5N via groups.io
Sent: Wednesday, March 19, 2025 2:32 PM
To: [email protected]
Subject: Re: [SoftwareControlledHamRadio] boards and kits and stuff

?

Hi Bill-

?

Is your board placed at the display end?? It seems like it is more of a "buffer board" rather than a driver board, if so.
I'm trying to visualize why it works.

?

--

73 Greg KF5N

T41_Display_Adapter_3.3&5V_V2.00_02-06-25.pdf

Main_Board_Mockup_For_Display_Board_V1.00_071424.JPG

Re: boards and kits and stuff

#33106

Hi Bill-

?

Is your board placed at the display end?? It seems like it is more of a "buffer board" rather than a driver board, if so.
I'm trying to visualize why it works.

?

--

73 Greg KF5N

Re: boards and kits and stuff

#33105

开云体育

The driver board seems to extend that to 6 feet (I can only measure the effect on a scope, not with the display)… someone else will give me the real story.

?

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it:

?

Moderator: North American QRO Group at Groups.IO.

Moderator: Amateur Radio Builders Group at Groups.IO.

?

email:? bill@...

?

Show quoted text

From: [email protected] <[email protected]> On Behalf Of Terrance Robertson, KN6ZDE via groups.io
Sent: Wednesday, March 19, 2025 1:40 PM
To: [email protected]
Subject: Re: [SoftwareControlledHamRadio] boards and kits and stuff

?

I've continued my T41 v12 display experiments.? A 9mm clamp-on ferrite worked with my 5.5" ribbon cable.?

?

It didn't work with the 11" or 15" cables I had on hand to test.? So somewhere between 6" and 11" seems to be the limit for this method.

?

Re: boards and kits and stuff

#33104

I've continued my T41 v12 display experiments.? A 9mm clamp-on ferrite worked with my 5.5" ribbon cable.?

?

It didn't work with the 11" or 15" cables I had on hand to test.? So somewhere between 6" and 11" seems to be the limit for this method.

?

Re: boards and kits and stuff

#33103

I have a 5V display.