Inexpensive RTC just wire in?

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Bikerbob
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Inexpensive RTC just wire in?

Postby Bikerbob » Tue Nov 07, 2017 4:13 pm

So, I have found several DIY projects that people have started,
http://fr.meric.free.fr/Articles/articl ... nside.html
https://blog.troed.se/projects/dallas-r ... s-y2k-fix/
and there is a kit on exxos site.. priced at 23pounds.
But there is this, a breakout board. https://www.ebay.ca/...~oAAOSwuMZZL4eH
https://www.maximintegrated.com/en/prod ... S3231.html
I should think with the people we have here an on other forums, its a matter of finding the lines to tap into on the ST, and we have a ready made RTC for $2?

Am I wrong?

James

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Re: Inexpensive RTC just wire in?

Postby czietz » Tue Nov 07, 2017 5:09 pm

It will be quite more complicated to wire in an I2C-based RTC like the DS3231 than the serial-shift-register-based DS1315 used on Exxos' board. Plus you'll need to find someone to write the software for that.

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Re: Inexpensive RTC just wire in?

Postby Bikerbob » Tue Nov 07, 2017 8:31 pm

ahh.. OK, was just a thought, at $2, you figured the hardware end is done, the datasheet is all there, base software like the one written that these other projects are using allow you to point to a address, I thought it might not be that hard.

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Re: Inexpensive RTC just wire in?

Postby czietz » Tue Nov 07, 2017 8:49 pm

It is not that hard. But it's still more to do than just soldering some wires to the cartridge port or whatever port. For example there's Till Harbaum's solution for interfacing an I2C bus using the ST's printer port: Right part of http://harbaum.org/till/atari/videotxt/schematic.gif. (Just think of your RTC on the left hand side instead of the SAA5246.) For sure, this circuit can be made internally as well.

But you still would have to completely rewrite the software for setting and reading the RTC.

I also thought about these cheap I2C RTC modules when I looked for a clock for my 1040STf. But in the end I decided to use an NTP (network time protocol) via Wifi solution instead, considering that the latter can also be built for less than 10 USD.

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Re: Inexpensive RTC just wire in?

Postby Zarchos » Tue Nov 07, 2017 9:11 pm

I have no idea if this can help, but in case you choose an I2C interfaced RTC chip, you could choose one where some settings (for configuration purposes) can be retained, too.
The Archimedes use this, and it is still being manufactured, and is very cheap :
https://www.nxp.com/docs/en/data-sheet/PCF8583.pdf

Hope this helps,

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Re: Inexpensive RTC just wire in?

Postby Dal » Wed Nov 08, 2017 12:00 am

Correct me if I’m wrong, but I seem to remember some years ago reading that the date and time functions on the ST were handled by the keyboard controller IC and there was a mod which essentially strapped a battery to this IC to hold its state after the machine was powered off. Not the most elegant solution but if you’re looking for the cheapest, then I can’t see much cheaper than this approach?
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Re: Inexpensive RTC just wire in?

Postby arf » Wed Nov 08, 2017 1:33 am

Dal wrote:Correct me if I’m wrong, but I seem to remember some years ago reading that the date and time functions on the ST were handled by the keyboard controller IC and there was a mod which essentially strapped a battery to this IC to hold its state after the machine was powered off. Not the most elegant solution but if you’re looking for the cheapest, then I can’t see much cheaper than this approach?


There’s also a solution described above from Troed where you put a Dallas chip in a ROM socket, and it is steered with a special software to deliver date+time. This should be rather simple to set up, and is internally. I think it is hard to beat.

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Re: Inexpensive RTC just wire in?

Postby Bikerbob » Wed Nov 08, 2017 3:29 am

except that I just found out that the Troed one will only work in a 2 chip TOS machine. SO, you either pay to convert the machine to 2 chip so you can put this in.. also the cheapest I have found the DS1216 is about $20 us from China. Also that solution is a built in battery, which if the chip is not fresh made.. 3years 5 years?? who know what you get out of it, and its garbage.. not a replaceable battery.

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Re: Inexpensive RTC just wire in?

Postby Bikerbob » Wed Nov 08, 2017 3:34 am

Dal wrote:Correct me if I’m wrong, but I seem to remember some years ago reading that the date and time functions on the ST were handled by the keyboard controller IC and there was a mod which essentially strapped a battery to this IC to hold its state after the machine was powered off. Not the most elegant solution but if you’re looking for the cheapest, then I can’t see much cheaper than this approach?


Its not so much that its the cheapest, but it is a mass production breakout board designed for Aduro and Pi and other microprocessor systems.. so this is not a DIY job, it should or so I hoped be easy to tie the lines to the correct address points, and you have a quality inexpensive RTC..

this one.. when I went to find the chip.. ended up being more expensive than the ds1216 http://fr.meric.free.fr/Articles/articl ... nside.html

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Re: Inexpensive RTC just wire in?

Postby Bikerbob » Wed Nov 08, 2017 3:42 am

czietz wrote:I also thought about these cheap I2C RTC modules when I looked for a clock for my 1040STf. But in the end I decided to use an NTP (network time protocol) via Wifi solution instead, considering that the latter can also be built for less than 10 USD.


Is there an article on this somewhere? assuming you dont have a cosmos or something you say 10 but you need a wifi dongle a way to attach it to the atari and then software?

I do have a microcosmos, which does do that when it boots. depending on what I am booting.. TOS/OS etc.. I have had a Y2K issue or not.. I wish I knew more about this function, does it somehow avoid the Y2k? or do you still need something that fixes it?

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Re: Inexpensive RTC just wire in?

Postby czietz » Wed Nov 08, 2017 7:17 am

Bikerbob wrote:Is there an article on this somewhere? assuming you dont have a cosmos or something you say 10 but you need a wifi dongle a way to attach it to the atari and then software?


Unfortunately, the description is only available in German: http://www.chzsoft.de/site/hardware/diverse-kleinigkeiten-fur-den-atari-st/#netzwerkzeit-ber-wlan-mit-esp8266. But Google Translate will probably give you the general idea. Basically, I use an ESP8266 microcontroller to do all the WiFi and NTP stuff, so that when queried over the serial port it'll just send the current time. People have rebuilt this using only ready-made components and jumper wires; no soldering.
Then of course I wrote software on the Atari side as well, to configure the module and to get the time at boot.

Bikerbob wrote:I have had a Y2K issue or not.. I wish I knew more about this function, does it somehow avoid the Y2k? or do you still need something that fixes it?


On my 1040STF with TOS 1.04 I don't have Y2K issues with my solution. (I understand this could be different with TOS 2.06.)

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Re: Inexpensive RTC just wire in?

Postby joska » Wed Nov 08, 2017 7:49 am

czietz wrote:But you still would have to completely rewrite the software for setting and reading the RTC.


Not really. The RTC driver for the MonSTer card comes with sources, and is compatible with the DS series of RTC's. The MonSTer does not actually have an I2C interface, just a couple of generic IO pins. So if you connect your RTC to some other IO pins in the ST (printer port, STE joystick ports...) all you have to do is to modify the I2C-routines in that driver accordingly.

http://www.fairlite.co.uk/AtariKit/monster/m_rtc.zip
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Re: Inexpensive RTC just wire in?

Postby AtariZoll » Wed Nov 08, 2017 8:03 am

Dal wrote:Correct me if I’m wrong, but I seem to remember some years ago reading that the date and time functions on the ST were handled by the keyboard controller IC and there was a mod which essentially strapped a battery to this IC to hold its state after the machine was powered off. Not the most elegant solution but if you’re looking for the cheapest, then I can’t see much cheaper than this approach?


Here is schematic and short description for it: http://atari.8bitchip.info/ikbdbatt.html
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Re: Inexpensive RTC just wire in?

Postby joska » Wed Nov 08, 2017 8:16 am

Please note that TOS does not handle dates > 2000 correctly when using the IKBD clock. To use this mod you will either need a patched TOS or a software patch of some sort.
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Re: Inexpensive RTC just wire in?

Postby Maeke » Wed Nov 08, 2017 11:20 am

Bikerbob wrote:So, I have found several DIY projects that people have started,
http://fr.meric.free.fr/Articles/articl ... nside.html
https://blog.troed.se/projects/dallas-r ... s-y2k-fix/
and there is a kit on exxos site.. priced at 23pounds.
But there is this, a breakout board. https://www.ebay.ca/...~oAAOSwuMZZL4eH
https://www.maximintegrated.com/en/prod ... S3231.html
I should think with the people we have here an on other forums, its a matter of finding the lines to tap into on the ST, and we have a ready made RTC for $2?

Am I wrong?

James

The board on exxos shop is actually based on the work in the first link, i know because i designed the first layout attempt and asked exxos to give me guidance since i didn't do this since 20 years.
Exxos found the project interesting and we continued working on it with a third person who did the tests on a stfm and a ste.
The final board is actually very ressemblant to the one i (poorly) designed but with all the mistakes corrected, this said we changed a bit the schematics since we wanted to use the cartridge port.
PS the price of the kit is due to the price of the ic, which isn't easy to find.
My attempt:
2017-11-08.png

The first test board i received (not the sold version):
P1000485.JPG

P1000496.JPG

Sadly due to a health issue (vertigos due to a damaged cervical vertebra) i still haven't finished installing it.
Forgot to say, troed contributed too.
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Re: Inexpensive RTC just wire in?

Postby Bikerbob » Thu Nov 09, 2017 2:20 am

thanks so much Maeke, I was not putting that project down, except for the same thing you pointed out the those DS1315 which are the chips that were used in the DS1216 units.. are not cheap. Where as this I2C board is.

joska, is that something you would have the expertise to do? I have not looked at the logic end of a chip is 30 years. Anyway.. was just looking for an alternative because the chips we do have "kits" for are getting expensive and old.

James

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Re: Inexpensive RTC just wire in?

Postby joska » Thu Nov 09, 2017 1:22 pm

Bikerbob wrote:joska, is that something you would have the expertise to do?


You mean modifying the I2C-routines in the MonSTer RTC driver? I guess so, depending on where you connect the RTC :) What kind of Atari do you want to use this in?
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Re: Inexpensive RTC just wire in?

Postby Bikerbob » Fri Nov 10, 2017 12:04 am

Well i was thinking for all the people who have not RTC, so the 520st stf 1040st stf.. those machines. I have a 520st and a 520stf(this one is hvy modded) and would like a clock in both if its doable.

Ok, so I need to figure out where to connect it in the machine, IO .. well more than anything its a matter of a convenient place to mount it. Any hardware guy good with logic circuits want to look at this? With the Monster driver, and a $2 board, we could have a nice little RTC kit here????

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Re: Inexpensive RTC just wire in?

Postby joska » Fri Nov 10, 2017 8:41 am

I2C has two signals - clock and data. Both are open collector. In an ST you can use the un-used IOA7 and very rarely used IOA6 (GPIO on the monitor port) on the soundchip for this purpose. As long as your RTC handles 5V signals no additional logic would be needed. Maybe a couple of pull-up resistors, but IIRC the YM's IO-ports have internal pull-ups so this may or may not be necessary.

I'm using this one in my STE with MonSTer:

https://www.ebay.co.uk/itm/2PCS-Arduino ... SwImRYbhIw

£1 for two including shipping :D
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Re: Inexpensive RTC just wire in?

Postby czietz » Fri Nov 10, 2017 2:12 pm

joska wrote:I2C has two signals - clock and data. Both are open collector. In an ST you can use the un-used IOA7 and very rarely used IOA6 (GPIO on the monitor port) on the soundchip for this purpose. As long as your RTC handles 5V signals no additional logic would be needed


Well, since the soundchip does not have open-collector/-drain outputs: how can you simultaneously have SDA (e.g. IOA7) as an input and SCL (e.g. IOA6) as an output then (as it is needed for reading from the RTC or even to receive an I2C ACK), without additional logic? As I already said: connecting an I2C RTC is not just as simple as soldering some wires.

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Re: Inexpensive RTC just wire in?

Postby joska » Fri Nov 10, 2017 2:41 pm

czietz wrote:Well, since the soundchip does not have open-collector/-drain outputs: how can you simultaneously have SDA (e.g. IOA7) as an input ...


You can't. I was under the impression that the YM's IO-ports had open collector, but apparently it doesn't.

So forget about this idea. You'll have to have some interfacing logic. I recommend a MonSTer card :)
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Re: Inexpensive RTC just wire in?

Postby Bikerbob » Sat Nov 11, 2017 4:07 pm

LOL joska, so, buy the MonSTer card and defeat the point. OK, well it was a nice idea. I guess I will look at one of the other projects that are out there.

As you said.. $2 for 2.. seemed to be too good to pass up and since so many other basic microprocessors can handle these I thought we might be able to too. worth a shot.

James


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