6502.org Forum  Projects  Code  Documents  Tools  Forum
It is currently Fri Nov 15, 2024 4:06 am

All times are UTC




Post new topic Reply to topic  [ 20 posts ]  Go to page Previous  1, 2
Author Message
 Post subject: Re: WDC W65C51A
PostPosted: Thu Apr 03, 2014 5:47 am 
Offline
User avatar

Joined: Thu May 28, 2009 9:46 pm
Posts: 8487
Location: Midwestern USA
floobydust wrote:
...WDC did send me some other chips to test.... none had the xmit bit stuck on, but all had other quirks which were mostly related to high noise levels and had limits on what I could manage with them. As a result, none of these could be used as direct replacements for existing NMOS chips as noted.

Noise levels? Can you describe what's going on?

Quote:
As for causing some grief in Mesa... well, not really my fault.

I was kidding about causing some grief. The fault is in the product, of course.

Quote:
Also, WDC has not updated the datasheet with errata showing the xmit bit problem...

I suppose they figure that they will fix the problem, so why edit the data sheet. I see this problem as more than errata, as it significantly complicates the use of the device in its intended application.

Quote:
...and the SCC2691 per the datasheet will have an upper limit of 6MHz, but I'm hoping 8MHz or more will be possible.

Shoulda went with the 26C92. :D That, I know, works at 15 MHz.

Quote:
I also am working on getting a SCC2691 chip setup, but due to real work and a ton of travel, I've just not had the time to finish up the initial hardware yet. And yes, the datasheet is a bit cryptic and vague, so it will likely take me some time to get it working once I have the initial hardware done.

Any questions please ask. I've extensively studied the 2692 and 26C92, and know the quirks and programming tricks.

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!


Top
 Profile  
Reply with quote  
 Post subject: Re: WDC W65C51A
PostPosted: Thu Apr 03, 2014 1:32 pm 
Offline
User avatar

Joined: Tue Mar 05, 2013 4:31 am
Posts: 1385
Hi BDD,

I received 3 other LOT numbers and all generated a lot of noise on the supply lines, and the boards are heavily capped.... even added more (caps) and it helped a bit. Two of the chips were noisier and all would not work with a crystal for the baud clock as the jitter was excessive. I did manage to get one to work using a can oscillator, but couldn't get any higher on the CPU clock rate than 4MHz IIRC.

The current chips (with the xmit bit problem) do work fine with a crystal and don't have the noise problems as the other samples, but requires the delay loop for transmit. So I guess in some ways they're pretty close on having a working chip, provided they can get the xmit bit fixed. I guess time will tell.

Hopefully I'll have some free time in the next month or so to get the SCC2691 going and thanks for the offer of support, much appreciated.

_________________
Regards, KM
https://github.com/floobydust


Top
 Profile  
Reply with quote  
 Post subject: Re: WDC W65C51A
PostPosted: Sat Apr 05, 2014 9:55 am 
Offline
User avatar

Joined: Sun Sep 08, 2013 10:24 am
Posts: 740
Location: A missile silo somewhere under southern England
floobydust wrote:
Hi BDD,

I received 3 other LOT numbers and all generated a lot of noise on the supply lines, and the boards are heavily capped.... even added more (caps) and it helped a bit. Two of the chips were noisier and all would not work with a crystal for the baud clock as the jitter was excessive. I did manage to get one to work using a can oscillator, but couldn't get any higher on the CPU clock rate than 4MHz IIRC.

The current chips (with the xmit bit problem) do work fine with a crystal and don't have the noise problems as the other samples, but requires the delay loop for transmit. So I guess in some ways they're pretty close on having a working chip, provided they can get the xmit bit fixed. I guess time will tell.

Hopefully I'll have some free time in the next month or so to get the SCC2691 going and thanks for the offer of support, much appreciated.

Hi floobydust

I've just received my 65C51Ns in the post. Can you tell if any of these match any of the ones you have which are affected?

W65C51N6TPG-14
A6A749.1
1016G015


Top
 Profile  
Reply with quote  
 Post subject: Re: WDC W65C51A
PostPosted: Sat Apr 05, 2014 12:46 pm 
Offline
User avatar

Joined: Tue Mar 05, 2013 4:31 am
Posts: 1385
Yes, those are the latest chips and have the xmit bit defect.

viewtopic.php?f=4&t=2543&start=30#p29001

The thread linked above has more detail.

_________________
Regards, KM
https://github.com/floobydust


Top
 Profile  
Reply with quote  
 Post subject: Re: WDC W65C51A
PostPosted: Sat Apr 05, 2014 2:26 pm 
Offline
User avatar

Joined: Sun Sep 08, 2013 10:24 am
Posts: 740
Location: A missile silo somewhere under southern England
floobydust wrote:
Yes, those are the latest chips and have the xmit bit defect.

viewtopic.php?f=4&t=2543&start=30#p29001

The thread linked above has more detail.

Thanks for confirming that, floobydust. I sent an email over to WDC to see what they'll do/say.
Hopefully they won't just point me back here, but offer to sort the issue out (i.e. fix the design). We'll see.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 20 posts ]  Go to page Previous  1, 2

All times are UTC


Who is online

Users browsing this forum: barrym95838 and 23 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to: