DIY CD drive based on a computer CDROM

[DJ]

Don't worry Variac, I for one won't give up on this project.

As for what EDY said, I agree to some extent. I was also under the impression we were all going to work together on this project, but it seems some people like mgb are already half way down the first straight. It seems that instead of step-by-step teamwork (which also implies the use of the same hardware etc), we should rather focus on teamwork such as posting tips and tricks we come accross here to help out one another. So don't despair EDY, we are actually working together.

By the way mgb, the DS89C420 is an excellent choice, I might use one myself since I have more than a few lying around. The rest of you might also want to take a look at it, it's a quite potent microcontroller.

Thanks for the link Holger. Don't let your love for Atmel blind you though, there may be better chips for the job out there! Just a suggestion for you golden oldies (that's you and Peter aka analog_sa), perhaps we should try to code in C instead. The reason I say this is because it will allow more people to mod their players by modifying the code (if anyone builds players based on our work later on). Just so you know, I don't have a problem coding in Assembler, so I guess I'm a real man too.

Your thoughts and suggestions are welcome as usual.

DJ

[Douchekop]

I'm gonna use this display

[Holger Barske]

Yes, go for it.
Seems to have the standard 16 pin connector and should be HD 44780 compatible, which is the standard controller vor LCD and VFD displays.

[Elkaid]

By the way mgb, the DS89C420 is an excellent choice

I worked a lot with DS89C420, if you plan to use it for a simple CD-Rom controller, then it's pure waste of power and cash (they're are much more expensive than a motorola, pic and atmel)

However, if you plan to use a RAM buffer then it's the perfect choice. Be aware that using computer RAM implies that it needs to be constantly refreshed. Static RAM doesn't need to but it's damn expensive.

[Holger Barske]

Chosing the right controller is the same as using tool: use the one you are used to and which has proven to be able to fulfill your needs.
After having a brief look at the DS89C420 I agree, it is a very powerful chip, especially for it's high clock rates. Concerning the peripheral features it's nearly the same as the Atmel ATmega16.

Ther are two reasons I won't use it:
1. It is hard to get here in Germany and extremely expensive. The only price I have found is 45 Euros for one(!) piece. I can get the Atmels for about 8-9 Euros.
2. I am completely out of 8051 programming.

If you would like to go with the Atmels, you may have a look at my (redesigned) prototype board. You can download the design files here:

http://www.hb001.de/atapictrl1_0.zip

The archive contains schematic, 600 dpi board layout (PDF, single sided) and stuffing guides.
It works with two controllers (as stated earlier), allows the connection of 8 switches, a standard LCD can be directly plugged in, a connection for an infrared receiver, power regulators for the circuit and the CD ROM.

I haven't built it yet, perhaps you might have a look and tell me where the errors are - there should be several.

This is how it looks:

[jleaman]

Looks like a nice small Board Good job.. !

[MCLL]

Great! Excellence! How about Firmware ?

[DJ]

Nice work Holger. I'll give it a good look this afternoon and let you know if I see any mistakes.

If you would like to use the DS89C420, you can get free samples from the website. Here's the URL:

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2963

Just scroll right down, you'll see where you have to click to order.

I agree with Elkaid, and the idea of using PC RAM (that I do have lying around) still looks promising, so the DS89C420 is still on top of my list. I might change my mind though, if Holger's PCB is as good as it looks, and if I can get Atmel chips over here.

What software did you use to do the layout?

Cheers

DJ

[Holger Barske]

I remember having read on another board that Maxim doesn't deliver samples of the DS89C420 - can't find it at the moment.

The layout is done with Eagle, availeable here. There is also a free version availeable.

[mgb]

Hi All,

The reason I choose for the DS89C420 was that it looked like I could get a free sample (have not received it yet) and that it was 8051 based. I found same software regarding interfacing the IDE controller that was based on an 8051. It was written in BASIC, so I don't think speed is an issue here. I didn't consider the price or the availabillity of the processor.

I Guess it's a good Idea to think about a processor all together. Some specs the processor needs to have are:

IO 16 pins for IDE communication.
IO for keyboard and display.
IO for in circuit programming.
Watchdog (option).

Yes, you can program in assembler but there are a few drawbacks when programming in assembler.
It's slow (programming that is).
It's hard to debug.
You probably will lose most of the thread followers since programming in Assembly is hard.
It's not portable.
Even QUAKE is not coded in assembly.

If you program in a language like C, BASIC or PASCAL. Porting the software to a different processor might be more easy. Also, the code would be eassier maintainable and the list of people willing to add snippets of code to the project will be larger.

Regarding the RAM. I think extra RAM should be an option to this project. First focus on the basic functionality of the CD-Player which does not need additional RAM.

MGB