Building Rolands new Atom design...

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Multiwizard
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Re: Building Rolands new Atom design...

Post by Multiwizard » Sun Feb 22, 2015 1:21 pm

PhilYoung wrote:Fixed it. And of course it turned out to be something quite mundane.

Case closed, thanks for the suggestions,

Cheers,

Phil Young
:D =D>

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Re: Building Rolands new Atom design...

Post by 1024MAK » Sun Feb 22, 2015 2:36 pm

@ Phil - Well spotted

This area looks okay on my board \:D/

Must have been a one-off defect :shock:

Mark

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Re: Building Rolands new Atom design...

Post by roland » Sun Feb 22, 2015 3:09 pm

I haven't noticed that either. Mark must be right, a one time fault. Maybe Kees can inspect this board. I have checked the Mk2 boards but they are all right on that spot.

Speaking about Mk2:
20150222_155853-1_resized.jpg
I have almost finished my first Mk2 board. But I didn't order a 33µF capacitor for the LM3940. I'm not sure how critical that value is, would a 100µF also do the job? And I ordered the wrong type of 1µF capacitors (Non-Polarized instead of elco's) and I also don't know if the MAX232 works with them....
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

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Re: Building Rolands new Atom design...

Post by PhilYoung » Sun Feb 22, 2015 3:39 pm

roland wrote:I haven't noticed that either. Mark must be right, a one time fault. Maybe Kees can inspect this board. I have checked the Mk2 boards but they are all right on that spot.
Hi Roland,

As you and Marc say it was certainly a one-off error during the board production. No harm done.

I was wondering though what the NET "DD(3)" BUFG=DATA_GATE and similar lines at the start of the VHDL are meant to do, and why they are necessary?

Cheers,

Phil Young

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Re: Building Rolands new Atom design...

Post by oss003 » Sun Feb 22, 2015 4:48 pm

Hi Roland,

looks like my board is ok.

Greetings
Kees

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Re: Building Rolands new Atom design...

Post by 1024MAK » Sun Feb 22, 2015 5:17 pm

Hi Roland :D
roland wrote:I have almost finished my first Mk2 board. But I didn't order a 33µF capacitor for the LM3940. I'm not sure how critical that value is, would a 100µF also do the job? And I ordered the wrong type of 1µF capacitors (Non-Polarized instead of elco's) and I also don't know if the MAX232 works with them....
If you have a 47µF that should work in place of the 33µF (he said fingers crossed, as that is the value that I'm using [-o< ). 100µF may work as well, but if I remember from reading the data sheet, the LM3940 may not be happy with values too far from the ideal value. The only way to know, is to try it, and use an oscilloscope to check that the regulator is not oscillating.

I would have thought that non-polarized 1µ capacitors would work okay with the MAX232. I'm sure I've seen a design using a MAX232 with ceramic layer 1µ capacitors somewhere. Are the type you have non-polarized electrolytic types? If yes, they should still work, but you may want to replace them when you get some normal electrolytic types, as I’m not sure what their lifespan is when subjected to a constant polarity (they are normally used in, or with AC circuits).

Mark

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Re: Building Rolands new Atom design...

Post by roland » Sun Feb 22, 2015 6:25 pm

PhilYoung wrote: I was wondering though what the NET "DD(3)" BUFG=DATA_GATE and similar lines at the start of the VHDL are meant to do, and why they are necessary?
If I leave these lines out then I get a warning "The global clock designation (BUFG) on signal 'Addr_3_IBUF' is ignored. Most likely the signal is gated and therefore cannot be used as a global control signal." so I think this is some kind of pin configuration.
Mark wrote: If you have a 47µF that should work in place of the 33µF (he said fingers crossed, as that is the value that I'm using [-o< ). 100µF may work as well, but if I remember from reading the data sheet, the LM3940 may not be happy with values too far from the ideal value. The only way to know, is to try it, and use an oscilloscope to check that the regulator is not oscillating.
I had some 100µF left so I used that one. The output voltage is 3.27V but I don't have an oscilloscope so I cannot see the quality of the output. According to the datasheet this should not be a problem:

EXTERNAL CAPACITORS
The output capacitor is critical to maintaining regulator stability, and must meet the required conditions for both ESR (Equivalent Series Resistance) and minimum amount of
capacitance.

MINIMUM CAPACITANCE:
The minimum output capacitance required to maintain stability is 33μF (this value may be increased without limit). Larger values of output capacitance will give improved transient response.

ESR LIMITS:
The ESR of the output capacitor will cause loop instability if it is too high or too low. The acceptable range of ESR plotted versus load current is shown in Figure 19. It is essential that the output capacitor meet these requirements, or oscillations can result.


I don't know the ESR of the capacitor I used, it is not mentioned in its datasheet. But the same goes for the 33µF I used in my first board.
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Re: Building Rolands new Atom design...

Post by 1024MAK » Wed Feb 25, 2015 5:17 pm

Things are moving forward... :wink:
image.jpg
All the DIL sockets are now fitted and I have added the SD card holder, the earphone socket and the 5V DC input socket.

I found that of the two stereo switched PCB mounting sockets I had, both nearly fitted, but the Switchcraft made one was closer to the PCB footprint. I had to file one pin down a little so that it would fit the PCB, and with a little help from a small flat bladed screwdriver on a couple of the other pins, I managed to get all the pins in their respective holes :mrgreen:. Then before the socket had a chance to get any ideas about escaping, I quickly soldered it in place :wink:.

The DC power socket required a bit more work. In total I tried five different types/makes (four 5.5mm/2.1mm and one 5.5mm/2.5mm). None correctly fitted the PCB. So I looked at each socket to work out which one would or could be modified to fit neatly. Four types were put back into stock, some because the pins were too big (wide) for some of the PCB holes.

Having found what I thought was the best, most easily modifiable socket, I set to work. The rearmost pin was carefully filed down so that it would nearly fit the PCB hole and so that it would be nearly straight when soldered to the board. But because the pin has a pre-drilled hole, there was a limit to how much width I could reduce it by. To enable the pin to go through the PCB hole, I also needed to use a small file to slightly enlarge the PCB hole. I used a small file to just cut two small slots either side so the pin just fitted and so the rest of the through hole plating was left intact.

Next, the front-most pin was filed down on both sides so the the width of the pin was narrower. It was test fitted, so I could mark the position on the top side of the board. I then drilled three 0.8mm holes in a line. Then expanded the three holes to made a slot. Now the front-most pin has a hole to go into :wink:.

A test fit showed that the socket was not quite straight, so a bit more cutting and filling... That's better. I soldered up the two pins that fitted in the plated through holes.

Now, the front-most pin needs to be electrically connected, to the unused PCB pad. I used some component off-cut leads to form a connection to the PCB pad. Job done 8)
image.jpg
image.jpg
image.jpg
Next, time to solder on the 4MHz oscillator, the capacitors, the CPLD sockets and the headers and the remaining connectors.

Mark

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Re: Building Rolands new Atom design...

Post by roland » Wed Feb 25, 2015 8:44 pm

The power connector looks as if it was made for the board =D> The good news is that with the right sockets from Farnell it is a lot easier to fit the audio and power connectors. I have build my MK2 board without any difficulties in less than four hours. Just the wiring between the Godil and the main board isn't in place yet. That's why I didn't power it on. I hope to complete this in the upcoming weekend. Probably Sunday evening.
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Re: Building Rolands new Atom design...

Post by roland » Wed Feb 25, 2015 10:14 pm

Another small bug found in Mk1 and Mk2 boards

Mark and Kees, before you solder the capacitors on the board please note that C1 and C2 are swapped. According to the diagram, C1 is at the input of the LM3940 and C2 is at the right side of the 74LS245 near the VIA. But on the board those are swapped, so you have to swap the values (C1 = 100 nF and C2 = 0.47µF). I have already changed the BOM on the website.

@Wim: you have the wrong capacitors on these positions. But no worry, just leave it as it is. It won't do any harm, I can't find any notice of this capacitor in the datasheet except that is required if the regulator is "far" away from the power filter. Besides the example circuit, no value is specified so I assume that a value of 100 nF is also usable.
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Re: Building Rolands new Atom design...

Post by 1024MAK » Wed Feb 25, 2015 11:29 pm

Hi Roland

I'd already noticed that C1 is not right next to the regulator, so am using a 100nF for this position.
I've just checked my notes and noticed that I had not amended the value for C2. So thank you for the information. I will now fit a 470nF polyester capacitor in the C2 position.

You posted just in time, as I intend to start soldering some of the capacitors tomorrow.

:D

Mark

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Re: Building Rolands new Atom design...

Post by Multiwizard » Thu Feb 26, 2015 6:57 am

roland wrote:Another small bug found in Mk1 and Mk2 boards

@Wim: you have the wrong capacitors on these positions. But no worry, just leave it as it is.
I just swapped C1 and C2 for just in case... 8)


Greetings, Wim... :-)


New Atom, steady as a Rock... :D

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Re: Building Rolands new Atom design...

Post by 1024MAK » Thu Feb 26, 2015 9:24 pm

A bit more progress:
image.jpg
image.jpg
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Re: Building Rolands new Atom design...

Post by roland » Sun Mar 01, 2015 9:47 pm

My dear friends,

Today I made a small video ( http://youtu.be/tEB0hXhVNh0 ) while powering on the first MK2 board for the first time. Did it work or not ... that was the question. Well, it worked from the very first power on \:D/

Until now I haven't found any errors. Ram and rom are working, AtoMMC2 (always critical runs happily at 1 and 2 MHz, audio is blowing my ears off, the Godil is working at standard Atom graphics and 80 columns, of course with the latest video extension.

This is a screen shot of the ultimate Atom memory test:
20150301_220024_resized.jpg
I did have a good look at Multiwizard's Atom as you can see in the video section. The video cable has seven shielded wires which makes the video signal a lot better than in my Mk1 Atom. With a little bit tweaking of the monitor's clock setting I could reduce the blue line interference to zero.

My next step will be to fidget the wires between the keys of the keyboard. Multiwizard told me how to do it. O, but first I have to split another old main board :mrgreen:

Ladies (where are you ???) and gentlemen, I'm ready for shipping the MK2 boards :D

Cheers,
Roland
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

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Re: Building Rolands new Atom design...

Post by Multiwizard » Mon Mar 02, 2015 5:59 am

roland wrote:Ladies (where are you ???) and gentlemen, I'm ready for shipping the MK2 boards :D

Cheers,
Roland
=D> :D =D>

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Re: Building Rolands new Atom design...

Post by Multiwizard » Mon Mar 02, 2015 6:14 am

roland wrote:My dear friends,

Today I made a small video ( http://youtu.be/tEB0hXhVNh0 ) while powering on the first MK2 board for the first time.

Cheers,
Roland
:-k
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Re: Building Rolands new Atom design...

Post by roland » Mon Mar 02, 2015 7:05 am

In an earlier post Roland wrote: And I ordered the wrong type of 1µF capacitors (Non-Polarized instead of elco's) and I also don't know if the MAX232 works with them....
Although Mark noticed that the non-polarized capacitors probably will work, I'm going to use the normal elco's. But I didn't order them yet. I don't expect any problems with that part of the board because it was not modified.
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
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Re: Building Rolands new Atom design...

Post by Multiwizard » Mon Mar 02, 2015 7:18 am

roland wrote:
In an earlier post Roland wrote: And I ordered the wrong type of 1µF capacitors (Non-Polarized instead of elco's) and I also don't know if the MAX232 works with them....
Although Mark noticed that the non-polarized capacitors probably will work, I'm going to use the normal elco's. But I didn't order them yet. I don't expect any problems with that part of the board because it was not modified.
I knew that... LOL :^o :oops:

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Re: Building Rolands new Atom design...

Post by roland » Mon Mar 02, 2015 7:39 am

multiwizard wrote:I knew that...
I know that you knew that. I mentioned it for readers that didn't know it :lol:
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Re: Building Rolands new Atom design...

Post by TheCorfiot » Wed Mar 04, 2015 2:02 am

Just putting my BOM order together for Farnell
The part number specified for the 3.5mm jack socket seems to be no longer in production.
Can anyone please quote a suitable alternative please.

Also what is the recommended parts for the 5V PSU connector and the cable header for the Godil please

Thanks
:)

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Re: Building Rolands new Atom design...

Post by roland » Wed Mar 04, 2015 8:32 am

Hi Bas,

It's bad news that the audio connector is not produced any longer. What's even worse is that they didn't notice me, I would have used another type. Now I have to go for a MK3 board :roll:

For some stupid capacitor Farnell send me an email, but for this part ... no way :cry:

For the power socket I used Farnell order code 1608726 which is still available. This code is wrong in the BOM, I will correct this. If you contact Farnell now, they probably can add it to your order!

Greetings,
Roland
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

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Re: Building Rolands new Atom design...

Post by 1024MAK » Wed Mar 04, 2015 9:15 am

I don't know how much this helps, on the earlier ("MK1"?) board, I used a stereo switched 3.5mm jack socket made by Switchcraft. Although the one I got came from Rapid not Farnell. I did have to file down one of the pins, as I describe in an earlier post in this thread.

But do keep in mind that I have no idea how much difference there is between the MK1 and MK2 boards.

The frustrating thing, is these stereo switched 3.5mm jack sockets often have very similar pin-outs, but one or two pins are spaced 2 to 4 mm different on each brand :twisted:

Mark

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Re: Building Rolands new Atom design...

Post by TheCorfiot » Wed Mar 04, 2015 9:24 am

Thanks for your help guys.

roland, i havent placed the order yet as i needed to add these parts inc sutable header for the Godil to PCB cabling :)

I will have a look for a suitable 3.5mm jack and let you know, hope we can avoid MK3 so soon.

:)

Edit .... Found them

http://www.ebay.co.uk/itm/5-Pcs-3-5mm-H ... 2c792694c2

Shall i order 10 or more and send them to you roland :)

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Re: Building Rolands new Atom design...

Post by roland » Wed Mar 04, 2015 10:31 am

Well, these look more like the jacks for the Mk1 boards (the Mk2 board has four pins in a row). These look more like the Mk2 type:

http://www.ebay.co.uk/itm/20-x-Audio-Co ... 5b02453ac5

I think it's worth ordering a 20 pieces. You can order them and if it fits, I'll buy the remaining 19 from you. Or, if you don't want the risk of getting stuck with 20 jacks, I'll take the risk and order them. In that case, they will be the Mk3 jacks :lol:
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Re: Building Rolands new Atom design...

Post by oss003 » Wed Mar 04, 2015 11:24 am

Hi guys,

I ordered the jack at Conrad:

http://www.conrad.com/ce/en/product/705 ... 6320-1-pcs

Greetings
Kees

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Re: Building Rolands new Atom design...

Post by TheCorfiot » Wed Mar 04, 2015 12:17 pm

Hi roland

doh, i was looking at pictures of the MK1 board lol..

OK, jacks ardered and i will post the remainder to you ;)

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Re: Building Rolands new Atom design...

Post by roland » Wed Mar 04, 2015 1:35 pm

oss003 wrote:Hi guys,

I ordered the jack at Conrad:

http://www.conrad.com/ce/en/product/705 ... 6320-1-pcs

Greetings
Kees
This part has only three pins and it won't be able to switch off the internal speaker when using a headphone or external speakers / amplifier. It's not a very big deal. I used to connect the Atom to the speakers of my monitor but since I have a monitor without audio I only use the internal Atom speaker. That makes enough noise :lol:
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

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Re: Building Rolands new Atom design...

Post by TheCorfiot » Thu Mar 05, 2015 4:45 pm

Lookie what arrived today :D

Spent a few hours building it but I'm still awaiting the VGA connector, LED's, Audio jack and I need to wire up the GODIL...

Huge thanks to Roland for all his help in arranging this beauty.

:)

EDIT --- Found a VGA connector in my spares box.
The ole girl worked first time. yay :D
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Re: Building Rolands new Atom design...

Post by roland » Thu Mar 05, 2015 6:53 pm

=D> You're in a hurry :lol:

What order number did you use for the 64 way connectors?
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Re: Building Rolands new Atom design...

Post by TheCorfiot » Thu Mar 05, 2015 6:59 pm

roland wrote:=D> You're in a hurry :lol:

What order number did you use for the 64 way connectors?

The one you have listed in the BOM, i studied the tech pdf and it looked fine so i ordered it.
it's a perfect fit :)

I need to find a clear diagram of the keyboard matrix, can you help ?
I can start hacking the spare Model B keyboard i have tomorrow.

She is alive as i shorted some lines on the keyboard connector and characters appeared onscreen.

It's such a tease, the prompt is staring at me but i cant type any thing lol.

Cheers Roly ;)

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