[Coco] SCART to HDMI project.

[Dave Philipsen]

74266 XNOR is not a very common chip.   I'm sure I don't have one in my parts bin.  But you can do the same logic with a couple of 7400s (which is probably *the* most common TTL chip).

Dave

> On Jun 13, 2017, at 1:43 PM, Salvador Garcia via Coco <coco at maltedmedia.com> wrote:
> 
> I had never heard of an XNOR gate, I had to look it up! 74266 :-) Salvador
> 
> 
> 
>      From: Doug Fraser <frase072 at telus.net>
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com> 
> Sent: Tuesday, June 13, 2017 1:18 PM
> Subject: Re: [Coco] SCART to HDMI project.
> 
> I was just thinking that. I might have a xnor chip in my collection. Good to know about pin 10. Thanks for that. Will investigate and post my findings. 
> Doug Fraser 
> 
> 
> Sent from my Samsung Galaxy smartphone.
> -------- Original message --------From: CoCo Demus <retrocanada76 at gmail.com> Date: 2017-06-13  11:03  (GMT-08:00) To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com> Subject: Re: [Coco] SCART to HDMI project. 
> Also should be a XNOR gate, because the signals are inverted on coco3.
> 
> On Tue, Jun 13, 2017 at 11:03 AM, CoCo Demus <retrocanada76 at gmail.com>
> wrote:
> 
>> Yes, you need to add a XOR TTL combining h-sync and v-sync and you can
>> disconnect the pin-10 and use it on the RGB connector. the pin-10 is used
>> only for the cm-8 for a strange detection system, all this undocumented.
>> 
>>> On Tue, Jun 13, 2017 at 10:33 AM, Doug Fraser <frase072 at telus.net> wrote:
>>> 
>>> That's possible. A good question is where should we get the h-sync and
>>> v-sync signals from? The project suggests the centre pin from the composite
>>> video to pin 20 on the scart connector (sync in). Is there a way to combine
>>> the rgb sync signals to replace the composite sync signal?
>>> Doug Fraser
>>> 
>>> 
>>> Sent from my Samsung Galaxy smartphone.
>>> -------- Original message --------From: CoCo Demus <
>>> retrocanada76 at gmail.com> Date: 2017-06-13  07:14  (GMT-08:00) To:
>>> CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com> Subject:
>>> Re: [Coco] SCART to HDMI project.
>>> For what you are describing: black and white, black stripes looks to me
>>> you
>>> connected coco3 composite video into a scart luma input.
>>> 
>>> On Mon, Jun 12, 2017 at 11:36 PM, Barry Nelson <
>>> barry.nelson at amobiledevice.com> wrote:
>>> 
>>>>> frase072 frase072 at telus.net  <mailto:coco%40maltedmedia.com
>>>> ?Subject=Re%3A%20%5BCoco%5D%20SCART%20to%20HDMI%20project.&
>>> In-Reply-To=%
>>>> 3Ctqar0lch5fyvl7tt6iq19drr.1497324709423%40email.android.com%3E>
>>>>> Mon Jun 12 23:31:49 EDT 2017
>>>>> 
>>>>> Just picked up an SCART to HDMI converter to replace my aging CM-8
>>>> monitor. After following Barry Nelsons project on hackaday.io I have
>>> had
>>>> partial success with a video image. Partial in that I have a black and
>>>> white screen and colors are grey scaled and artifacted with vertical
>>> black
>>>> lines. I'm not sure what is going on with the signal.  Does anyone that
>>> has
>>>> done this project have any insights as to how to make this work?
>>>>> Doug Fraser.
>>>> Can you post a picture of the screen? Make sure you connected all the
>>>> ground wires and that you have 5 volts applied to the 100 ohm resistor.
>>>> Double check all your wiring and measure the voltage on pin 16. Maybe
>>> you
>>>> got a bad converter, post a photo of the wiring also please, I may be
>>> able
>>>> to help more after I see the pictures.
>>>> 
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>>> 
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>> 
>> 
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