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Re: Display driver board reality
¿ªÔÆÌåÓýNot quite that simple¡ Some, but few zeners operate at 10 MHz like the SPI clock and data signal lines do.? What you get instead is something that looks like a mountain shaped waveform.? People have learned this the hard way thinking they can use them as boas clipping diodes on RF transistors only to find that the transistors still blow up. ? ? 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: Friday, February 7, 2025 10:20 AM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] Display driver board reality ? Just a thought but I am no EE.? I like the guidance and list.? The only remaining issue is? ? or if you DO have the level change hardware on your display board but have not selected it ? Is it not possible to use a 3.3v zener to clamp and protect this.? This would prevent from destroying the RA8875.? ?It may be the circuit would not function properly if the zener clamps, but at least the RA chip would not be destroyed.? Then the builder can resolve by selecting the level change. ? Maybe it helps, maybe not ? |
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Re: [AmateurRadioBuilders] Display Adapter
No. data line voltages at 3.3 and VSS to the display requlator of 5V...
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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 9:25 PM To: [email protected] Cc: [email protected] Subject: Re: [SoftwareControlledHamRadio] [AmateurRadioBuilders] Display Adapter By "operating the display at 5V", you mean 5V logic? - Jerry, KF6VB On 2025-02-06 19:17, K9HZ wrote: This one will work for operating the display at 3.3V and 5V. It's |
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Re: Display driver kits shortly
¿ªÔÆÌåÓýWell let¡¯s check that out. ?
? So sometimes better, sometimes worse¡ but that¡¯s why I use Octopart¡ to always find the cheapest price on parts. ? ? 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: Friday, February 7, 2025 6:16 AM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] Display driver kits shortly ? [Edited Message Follows] Bill and all ? I'm surprised more people are not using LCSC for components, they are the sister to JLCPCB. ? Prices are mostly far better than Digi or Mouser, it just takes a little longer for deliveries. I won't enter into tariffs here. In Aus. the govt steals an extra 10% on everything that enters the country anyway. ? I did a search on LCSC for those female headers, there's like 50 to choose from down to 4 or 5c ea at qty 400+, and 9c ea for qty 5+ - filter for "Holes Structure" = 2x5P and "in stock" gives 75 hits. ? Worth checking out comparisons against the other companies... ? ? Regards |
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Display Adapter
¿ªÔÆÌåÓýThis one will work for operating the display at 3.3V and 5V.? It¡¯s about $0.60 more that the strictly 3.3V driver board. ? ? 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 board reality
¿ªÔÆÌåÓýYep that¡¯s what I found¡ ? ? 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 Terrance Robertson, KN6ZDE via groups.io
Sent: Thursday, February 6, 2025 6:31 PM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] Display driver board reality ? I have a number of these displays (both 5" and 7").? All can either run on 3.3 or 5V with jumper change (they all have a 3.3V regulator for 5V operation).? All are only 3.3V on the data lines, no level converters. |
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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? |
K9HZ
Tom Clifton