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Author Topic: Sega PC Mark II  (Read 6599 times)

Offline Arinoth

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Sega PC Mark II
« on: March 26, 2015, 09:37:48 PM »
It's about that time to finally start posting about my second attempt at moding a Sega Genesis Version 1 case and sticking a mITX PC into it.

This time it will be greatly different then last for multiple reasons.
  • I will be using proper tools to cut the backing as well as anything else within the case to ensure the items can proper fit, this is a change from using a handsaw last time which...didn't turn out that professional looking...
  • Everything will 'work' on the Sega Genesis as if it were a real Genesis:
    • The volume slider will change the volume in Windows
    • The power button and reset buttons will be usable, there will be a conversion of the pole switch to push button.
    • Headphone jack will operate correctly.
    • The controller ports will convert controllers into USB controllers.
    • LCD Screen that will show the Sega Genesis Logo on bootup of the PC, also play the SEGA bootup music we all know and love.
    • LCD Screen that will show/cycle through sponsored images when the PC is on
  • Probably a few more things too that will be added later on.

The list of the PC parts is still changing, as it will depend on what the sponsoring Real Hardware Reviews gives me to work with. I will update that when it keep changing and I have the parts in my hands.

To accomplish half of the tasks mentioned I will be using an Arduino to do some of the 'heavy' lifting. This is a perfect segway into what I have accomplished so far with the electronics sides of things.

The slider was one of the easier things to start with, as it is just hooked up to the Arduino's power source, ground, and to an analog input port. As it ranges from 0 to 1023 I need to drop this down to the number of 'steps' that the PC can boost the volume at. Turns out a volume increase or decrease command or keyboard event changes it by a value of 2 rather than one. This means going from 0 to 100 in volume I only have 50 steps. Dividing by 10.23 gives me a range of 0 to 100, which is perfect. I can send that value to the PC then have the PC program divide tat by 2 and give me the correct volume levels.

There are a few kinks to work out, the main one being that the Arduino and PC need to be synced to whatever the Arduino volume slider is set to when the PC is turned on. I need to fiddle with a few things, potentially making the slider not as sensitive since really I only need 50 steps, and I'm converting from 1024 steps.

I bought what is called a TFT LCD Module with SD Card Reader. The screen is 1.77" diagonal, with 160 x 128 pixel resolution, which is more than a perfect size to fit up inside of a Genesis cartridge, replacing where the game logo/sticker would be. The benefit of it having an SD Card Reader in it is that I can copy whatever image I want in bitmap form, put it on there, then just push the image from the SD card to the LCD using the magic of an existing Arduino library.

Here is the first working test of the Arduino Uno driving the TFT LCD Module:

Notice how slow it takes for the LCD to load an image, this is due to the speed of the processor and SPI lines.

I was able to borrow an Arduino Mega from a school friend who happens to live in the city to see if the more powerful Mega would allow me to load faster:

It is faster however you can still notice it takes more than a half a second to load the image.

To remedy this I went searching on the internet for solutions. I found out that the Arduino Due (which I have since ordered) is able to load images faster, especially with library someone has made using DMA. In test videos I've seen it load an image almost instantly, perfect for me to do the intro Sega music/animation when the PC turns on. As of right now I am waiting for it to come in the mail, so anything else with the LCD will mainly be adding more pictures to it, and hooking up the power and backlit to a transistor so I can turn the screen off with the Arduino when the PC is off.

With the LCD screen working and well on hold, I moved onto the second part of the Sega Bootup portion. This involves hooking up a speaker to the Arduino and then using a few libraries for it to play back audio. The fortunate part of having that TFT LCD module with SD Card is that I can store wav files on it and access it to push the audio out to the speaker.

After several hours of trying to figure out the library and how to properly hook it up I was rewarded with this:

Notice how quiet it is, this is due in part to the fact the Arduino output port has a rather low maximum current output on it (40 mA). At 5V (though it's PWM so it's never quite at 5V) the maxium wattage I can kick out is 200mW.  As the speaker is an 8 Ohm 0.5W speaker, this is only about half the maximum it can receive.

I need to boost the signal, need to amplify it to be exact. Well I grabbed a trust NPN transitor, a resistor and configured it in a way to amplify the current. PLEASE NOTE, LOWER YOUR SPEAKERS ON THIS NEXT VIDEO:

As we can see this is considerably louder, to lower it, which I plan to, I'll need to change around the resistor I'm using, large the resistor, the lower the current being sent to the amplifier and thus quieter the speaker will get.

What I also need to do is throw on a high pass filter into this circuit to filter out any DC coming from the Arduino output as to make the sound a bit more crisp.

So far this is all I have to update, though as I stated I'll be tackling more of the PC volume control section shortly and hope to have that done. After that I plan to look at the Reset and more importantly the power button/switch configuration and how to determine when the PC is on or off (I have a few ideas that I'll need to test out).

Hopefully all will go well with this project and that it explained in a way that both the technical electronic hobbiest knows some of the nitty gritty details and that the average modder will understand too. Either way, let me know what you think, in the end this may end up becoming a contest prize, but we'll see with my sponsor later on.
« Last Edit: March 26, 2015, 09:45:44 PM by Arinoth »

Offline Soullessone21

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Re: Sega PC Mark II
« Reply #1 on: March 28, 2015, 01:33:13 PM »
Looks good Sam, great work with the sega sounds and setting up the display.

Looking at boards and stuff next week just need to make sure they will work with all the components your adding to it.

Real Hardware Reviews is always accepting guest reviewers, email me if your interested.


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Re: Sega PC Mark II
« Reply #1 on: March 28, 2015, 01:33:13 PM »

Offline Arinoth

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Re: Sega PC Mark II
« Reply #2 on: March 29, 2015, 08:45:24 PM »
Haven't had an overly 'great' weekend aside from being able to make some headway on Friday evening.

The volume slider now works so that whatever level the potentiometer slider is at, will result in changing the Windows volume correctly. The more challenging part was making it so that if the Arduino or PC are off and someone changes the volume slider that once the PC is on its volume is correctly set to this new offline value. This took a few hours to troubleshoot but it's been solved too.

The other accomplishment of Friday was the ability to turn on/off the LCD with SD Shield whenever I want. There is no point in having the LCD screen on if the PC is off as it would be a waste of power. This was resolved by using a NPN transitor and a circuit configuration to allow it to act like a digital switch. If the transistor get a high, it will turn the LCD on, if it gets a low it will turn the LCD off.

There will be some video of both of these things in action within the next day or two, just wanted to update people.

Offline Arinoth

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Re: Sega PC Mark II
« Reply #3 on: May 26, 2015, 04:11:37 PM »
I just received two BROKEN/FOR PARTs Sega Genesis Gen 1s off of eBay for about the same price I was seeing online or locally for one working one.

Now to wait for some other parts (new audio 'chip', different LCD display) before I start this back up. That and my Witcher 3 review.

Online Bond007

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Re: Sega PC Mark II
« Reply #4 on: May 27, 2015, 09:26:40 AM »
Nice find
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Offline Arinoth

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Re: Sega PC Mark II
« Reply #5 on: October 05, 2015, 02:07:14 PM »
Should be seeing some new news about this shortly as more parts trickle in very shortly. Let's just hope my code still works with a few alterations that'll be coming along too. Namely the audio decoder and the newer LCD screen.

Offline RapidQuick

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Re: Sega PC Mark II
« Reply #6 on: October 05, 2015, 02:31:31 PM »
Should be seeing some new news about this shortly as more parts trickle in very shortly. Let's just hope my code still works with a few alterations that'll be coming along too. Namely the audio decoder and the newer LCD screen.

Can't wait to see it!

Offline Arinoth

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Re: Sega PC Mark II
« Reply #7 on: October 12, 2015, 01:12:05 PM »
Time for an update.

I purchased several months ago a slightly larger 2.2" 240 x 320 TFT LCD screen that works with a specific DMA library that is supposed to decrease how long it takes for an image to be displayed on the LCD display if it is connected to an Arduino Due.

]
We can see in the attached Youtube video that the RHR Logo, takes only about 113ms to load each time (there is an timer program built in to let one know how long it took). Comparing that against the previous above videos it is a great accomplishment, potentially even allowing me to make the 'animated' Sega animation that I was hoping to when the PC boots up.

Offline Soullessone21

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Re: Sega PC Mark II
« Reply #8 on: October 13, 2015, 01:34:19 PM »
Time for an update.

I purchased several months ago a slightly larger 2.2" 240 x 320 TFT LCD screen that works with a specific DMA library that is supposed to decrease how long it takes for an image to be displayed on the LCD display if it is connected to an Arduino Due.

]
We can see in the attached Youtube video that the RHR Logo, takes only about 113ms to load each time (there is an timer program built in to let one know how long it took). Comparing that against the previous above videos it is a great accomplishment, potentially even allowing me to make the 'animated' Sega animation that I was hoping to when the PC boots up.

Looks good, looks better then the older video for sure.

Would love to see a sega start screen on it :)

keep us posted on how things go as I hear more parts for this just showed up
Real Hardware Reviews is always accepting guest reviewers, email me if your interested.


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Offline RapidQuick

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Re: Sega PC Mark II
« Reply #9 on: October 13, 2015, 01:48:27 PM »
Looks good, looks better then the older video for sure.

Would love to see a sega start screen on it :)

keep us posted on how things go as I hear more parts for this just showed up

Can't wait to see Sonic

Offline Arinoth

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Re: Sega PC Mark II
« Reply #10 on: October 13, 2015, 02:03:32 PM »
The plan is to get to that point, that's why I need to work on audio (if it'll be possible with the Arduino Due), need an LM386 itself or pay a little more and get a premade circuit with it. Downside would be buying it from China meaning weeks of waiting for it.

According to Canada Post, the PC hardware side was delivered today, so that should help push along the physical case modding now.

Online Bond007

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Re: Sega PC Mark II
« Reply #11 on: October 13, 2015, 03:47:45 PM »
Good luck
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Offline RapidQuick

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Re: Sega PC Mark II
« Reply #12 on: October 13, 2015, 05:24:51 PM »
How many games will you be able to put on it? Will it be portable like a tablet? That would be cool. Also, will it work with  a controller?

Offline Arinoth

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Re: Sega PC Mark II
« Reply #13 on: October 13, 2015, 05:52:09 PM »
Look what just showed up:


Suppose I should open it?


Here is the PC that'll be going inside of the Sega Genesis itself:


Removed from its box:

We will be upgrading those 2x1GB to 2x2GB since who runs 2 Gigs of Ram these days?

Decided to crack open the Sega Genesis itself (remember this is a DEAD unit)


An up close shot of internals a Sega Genesis:


Removed the metal shielding around the Coax that was there probably to reduce EMF noise


I have also performed a brief 'fit' test to see how well the motherboard will fit in the gutted Sega Genesis, it fits 'alright' so far, but I will still need to drummel down some of the support pegs inside in order for it to properly sit in there, not to mention cut out the rear I/O panel as sadly none of it lines up that well. If I can get a better shot of the motherboard in the Genesis I'll post it.

Offline Arinoth

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Re: Sega PC Mark II
« Reply #14 on: October 13, 2015, 05:54:00 PM »
How many games will you be able to put on it? Will it be portable like a tablet? That would be cool. Also, will it work with  a controller?

It is going to run a full version of Windows for the most part, so whatever Roms that are out there for a Sega Genesis emulator or other emulators. I do have some Sega Genesis to USB adapters that I will be using, though I may have to mod them slightly in order for them to sit correctly as oddly the manufacturer DID NOT make the distance between the controllers the same as on the console itself.

 

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