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Display driver board reality
¿ªÔÆÌåÓýOh brother, this is starting to get complicated. ? The RA8875 is a 3.3V chip¡ and the inputs, as far as I can tell¡ from my research so far¡ are only 3.3V tolerant.?? ? To make this more confusing, some of the display.com displays have level shifting hardware onboard that you can enable to use the display as a 3.3V display or as a 5V display (in line with the power selections on the MAIN board).? However, not all do (particularly the smaller displays). ?The boards I made work with 3.3V and 5V display boards¡ which is fine for 3.3V operation for all display boards¡. The problem comes if you select 5V operation bon the MAIN board¡ but either don¡¯t have a 5V control line selection on the display board for level change to 3.3V for the RA8875¡ or if you DO have the level change hardware on your display board but have not selected it.? In this case, you will destroy the RA8875 chip. ? I can do two things.? One is to put together a list of all the approved Display.com display part numbers (upper middle of the back of the display) and give guidance on what you need to do so that the display continues to function with this driver board.? The other thing I can do is make a second board that has a tiny 3.3V regulator on it to power the three control lines to just 3.3V in the case of running the display off 5V but no hardware is there for level shifting the data lines to 3.3V. ? Comments? ?????? ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C 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@... ? ? |
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Re: Display driver kits shortly
Those are 2mm, not 2.54mm.? ( I suspect you can find the .1" pitch there as well)
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Re: Display driver kits shortly
¿ªÔÆÌåÓýWell fact is¡ I¡¯ve already done that¡ sort of¡. For my prototype, I installed a 2x4 socket in a 2x5 holes pattern on the PCB knowing full well that 2 of the 10 holes on the end of the 2x5 connector are N/C. ? However, good news!? I was able to find 10,000 of them surplus for a very low price.? They will be here next week. ? There is another issue I discovered.? The ISO7241 SPI driver chip has two forms¡ an ¡°M¡± form and a ¡°C¡± form.? Here is the difference: ? ¡°The devices with the C suffix (C option) have TTL input thresholds and a noise-filter at the input that prevents transient pulses from being passed to the output of the device. The devices with the M suffix (M option) have CMOS VCC/2 input thresholds and do not have the input noise filter or the additional propagation delay.¡± ? For electrically operating it won¡¯t make a difference.? What might make a difference is the noise filter in the ¡°C¡± version and I have not explored that (eg only have used the ¡°M¡± version.?? I suspect the ¡°C¡± version may work better for people in high EMI situations.? So I¡¯m gonna make a few of each¡ send them out to a few folks here with finished radios and see which works best for them.? Unfortunately, I don¡¯t have a high EMI location¡ so for me testing them may not be a fair comparison. ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C 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@... ? ? From: [email protected] <[email protected]> On Behalf Of bruce williams via groups.io
Sent: Thursday, February 6, 2025 12:11 PM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] Display driver kits shortly ? Or depending on layout can you use the 2x6 and just snip 2 pins.? Is there real estate on the board for that? |
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Re: Display Noise
Do you have a piece of aluminum you can put behind the display and clip-lead
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it to ground to test if a shield will work? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. email:? bill@... -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of jerry-KF6VB Sent: Thursday, February 6, 2025 10:54 AM To: [email protected] Subject: [SoftwareControlledHamRadio] Display Noise The upper bands are open this morning - I heard a W2 on 10M. Listening on 15 right now. I can hear the display. It makes a rhythmic grinding noise. Here's something interesting.. ...I put my hand up to the outside of the display - and the grinding noise gets quieter. I can only guess that my hand absorbs RF out of the display. - Jerry, KF6VB |
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Re: Display driver kits shortly
¿ªÔÆÌåÓýThe right ones will work¡., but they need to be the thin versions or it¡¯s a struggle. ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C 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@... ? ? From: [email protected] <[email protected]> On Behalf Of bruce williams via groups.io
Sent: Thursday, February 6, 2025 10:05 AM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] Display driver kits shortly ? If you cant get a reasonable price, how about just sandwiching two 1x5 headers? |
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Re: Display driver kits shortly
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Re: Display driver kits shortly
Check Amazon 25 for $7 " Brand Pro"
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25-Pack 10P 2.54mm 0.1" Pitch PCB Female Pin Headers 2x5 Dual Rows 10 Pins Female Sockets to Male Straight PCB DIP, Double Rows PC Board Through-Board Strip (2x5-10P-25PK)
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Display driver kits shortly
¿ªÔÆÌåÓýWith one or two exceptions¡ I¡¯ll put together kits for the display driver.? I can even have a few of them built for those who want a finish product (my daughter-in-law is a stay at home EE who needs something to do.? She has built stuff for me before). ? One thing¡ I need some help finding the part in the attached diagram at a reasonable price (like it should be about $0.15 max each)¡ it¡¯s a 10 pin female socket, 2x5, PCB mount.? Tayda has 2x4 and 2x6 but not 2x5 for whatever reason.? Digikey and Mouser are sky high. ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C 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@... ? ? |
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Re: SMD Stencil/Reflow solution?
¿ªÔÆÌåÓýYeah it doesn¡¯t work very well for Capacitors or Inductors because the test frequency is so low¡ but I like the size¡ ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C 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@... ? ? From: [email protected] <[email protected]> On Behalf Of Phil Taylor via groups.io
Sent: Wednesday, February 5, 2025 10:09 PM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] SMD Stencil/Reflow solution? ? [Edited Message Follows] I ended up buying the FNRISI tweezers also. ? A note of caution.? Some capacitors read quite low from auto. When I played with the measurement frequency, things were better. ? -- Regards |
K9HZ
Tom Clifton