New Raspberry Pi to 1MHz bus interface

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dp11
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Re: New Raspberry Pi to 1MHz bus interface

Post by dp11 » Tue Jan 21, 2020 11:50 pm

It should be possible to add the pull up in software on the pi and still only have one build.

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KenLowe
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Re: New Raspberry Pi to 1MHz bus interface

Post by KenLowe » Sat Jan 25, 2020 12:08 pm

My sample boards arrived today:
20200125_102651.jpg
Batch of boards received from JLCPCB
I'm glad I didn't have to solder in those components. Some of them are mircoscopic!!!

First job was to solder in the headers, and verify that it would fit under the Master, and that it would co-exist with PiTubeDirect. As I thought, it's a tight squeeze, but it all just fits:
20200125_105647.jpg
Tube and 1MHz level shifters in Master
20200125_105754.jpg
RPi Zeros plugged into level shifters in Master
Next job was to add the power connectors, and the extra pull ups:
20200125_114440.jpg
Component side of board
20200125_114459.jpg
Underside of board with patched pull ups
And then plug into my beeb, and test:
20200125_114145.jpg
1MHz level shifter with RPi Zero plugged into my beeb
20200125_114242.jpg
Working SCSI drive :)
That looks to be a success!
dp11 wrote:
Tue Jan 21, 2020 11:50 pm
It should be possible to add the pull up in software on the pi and still only have one build.
That would be really good. It would avoid me having to patch in the pull ups on these boards. However, the next rev of the board includes the pull ups, so it's not critical. The next rev of board is also marginally smaller, and has exactly the same footprint as the PiTubeDirect level shifter, so should also be slightly easier to fit under the Master.

I'll be in touch with a couple of you shortly by PM to see if you would be willing to help with testing, before I start offering them to the wider public.

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KenLowe
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Re: New Raspberry Pi to 1MHz bus interface

Post by KenLowe » Sat Jan 25, 2020 4:57 pm

...and here's one of my beebs with 2 x RPi Zeros:
20200125_164155.jpg
PiTubeDirect + SASI HDD / Music 5000 System
20200125_164244.jpg
ADFS SASI HDD and Tube running via 2 x RPi Zeros
Power for the 1MHz level shifter / RPi Zero is currently being taken from the User port. In future hope to be able to take power from my new Tube port level shifter.

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KenLowe
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Re: New Raspberry Pi to 1MHz bus interface

Post by KenLowe » Tue Feb 04, 2020 3:18 pm

A quick update for those who are waiting. There was a bit of a delay to testing as I tried to get a Master up and running over the weekend, so I could run the Music 5000 software. That's now done, and testing with the Master is ongoing. Now that I know what I'm doing with Music 5000, I've also managed to get it running on a beeb. Results so far:
  • The basic level shifting functionality is working fine.
  • The current board is missing two pull up resistors. These have been patched into the test boards, and Dominic (dp11) has implemented a potential software solution that removes the need for the pull ups. This is currently under test. I have added these pull ups into a revised board design, so in time this will become a moot point.
  • The board just about fits into a Master. It needs to be pushed in at an angle, but I have been able to squeeze the boards into my 3 Masters without having to dismantle them. However, I have had one report that it was necessary to slacken off the Master motherboard screws and push the motherboard back a little bit in order to fit and remove the board, so that risk exists with the current board. I've been able to shave off a couple of mm from the board design, so future boards should have less of an issue. However, this may start to impact the fitting in a standard beeb as the edge of the RPiZero is already very close to the edge of the BBC case. It's undoubtedly going to need to be a compromise between the two.
  • Quality of audio pass through from the RPiZero to the internal Master speaker is relatively good.
  • On the other hand, quality of audio pass through from the RPiZero to the internal beeb speaker is relatively poor. A lot of noise is being picked up once the RPiZero has booted up. This is even with a physical wire disconnection between the RPi audio out, and the 1MHz audio in. Investigations ongoing.

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Re: New Raspberry Pi to 1MHz bus interface

Post by aotta » Tue Feb 04, 2020 11:25 pm

Great work! I'd like two board too, please add me to the list

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IanB
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Re: New Raspberry Pi to 1MHz bus interface

Post by IanB » Thu Feb 06, 2020 1:04 am

Looks good, I'd be interested in a couple of them with matching tube adapters.

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Re: New Raspberry Pi to 1MHz bus interface

Post by th3bar0n » Thu Feb 06, 2020 9:27 pm

Apologies, could I upgrade to two 1Mhz boards, and add two tube adapters as well.
Thanks!

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KenLowe
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Re: New Raspberry Pi to 1MHz bus interface

Post by KenLowe » Fri Feb 07, 2020 1:43 pm

It's probably going to be a few weeks yet before I can start offering these for sale. I've been working with a couple of the forum members to try and address the audio quality issues I mentioned earlier, and I'm hoping we're just about there now. I'm just waiting for some components so I can test the theory, before then ordering a small number of Rev 2 prototype boards. Once they're proven, I can then place a bulk order.

Latest board layout now includes the additional circuitry to try and improve the sound quality, and I've also added a couple of LEDs, just because I can! Not much room left on the board now...
1MHz Interface 14.PNG
Latest board layout

mph1708
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Re: New Raspberry Pi to 1MHz bus interface

Post by mph1708 » Fri Feb 07, 2020 7:31 pm

My I add my name to list of people declaring an interest in obtaining one (or two) of these boards when they become available.
Regard

Mike

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tone76
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Re: New Raspberry Pi to 1MHz bus interface

Post by tone76 » Mon Feb 10, 2020 11:42 am

Just adding another expression of interest to the pile. :)
Acorn Electron
BBC Model B (Issue 7)
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KenLowe
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Re: New Raspberry Pi to 1MHz bus interface

Post by KenLowe » Mon Feb 10, 2020 12:55 pm

*** This post is no longer being updated. Please refer to For Sale thread for latest detail ***

Ok folks, I've placed an order for a 2nd batch of boards. I'm still not taking orders yet, but assuming they work as expected, then the following is the list of noted interest in the order I received it. If you think I've missed your name out, or if you would like your name added, please let me know, and I'll update this list.

Once I'm ready to accept orders, I'll create a new thread in the For Sale section. Worth highlighting that I have a batch of Tube adaptors on order as well.

Update: Batch 2 is now all accounted for, but I'll still take notes of interest for Batch 3. I won't actually place an order for Batch 3 until Batch 2 arrives, and I'm happy that they're working correctly.

Batch 2 - All shipped
User 1MHz Tube Status
tucker 1U - Posted 02/04
marcusjambler 1U 1U Posted 19/03
tricky 1U 1U Posted 19/03
mr-macrisc 1U - Posted 21/03
th3bar0n 2U 2U Posted 22/03
Stewie66 1U - Posted 27/03
CJS 1U - Posted 19/03
awilliams 1U - Posted 19/03
markrwj 1U + 1RC 1U Posted 21/03
rharper 1U - Posted 20/03
Rod C 1U 1U Posted 19/03
Alan00 1U + 1R - Posted 24/03
roganjosh 1R - Posted 25/03
Remklep 2U - Posted 19/03
1024MAK 2U 2U Posted 21/03
Kazzie - 1U Posted 20/03
Wheel_nut - 1U Posted 22/03
aotta 2U 1U Posted 22/03
IanB 2U 2U Posted 23/03
dominicbeesley 1R - Posted 23/03
mph1708 1U + 1R 1U Posted 24/03


Batch 3 - Completed
User 1MHz Tube Status
BCCweirdo 1U - Posted 15/04
tone76 1U 1U Posted 23/04
Boydie 1U + 1R 1U Posted 19/04
DaveLecky 1U 1U Posted 14/04
shakesc 1U - Posted 14/04
crowly 1U - Posted 15/04
egel 1U + 1RC 1U Posted 15/04
jimmy 1U 1U Posted 16/04
anightin 1U 1U Posted 14/04
PJ via email 2U 2U Posted 18/04
trixster 2U 2U Posted 29/04
Simon 1U - Posted 17/04
JW via Facebook 1U 1U Posted 19/04
cr12925 1U - Posted 03/05
BeebMaster 2U - Posted 06/05
cr12925 - 1U Posted 07/05

Batch 3 - In progress
User 1MHz Tube Status
DamienSturdy 1 - Await response
jms 1U 1U Await response
Seldon2k 1U + 1R 1U + 1R Await response
Followed up 06/05
MR via Facebook 1U - Await response
Followed up 06/05
Last edited by KenLowe on Thu May 07, 2020 10:44 pm, edited 34 times in total.

shakesc
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Re: New Raspberry Pi to 1MHz bus interface

Post by shakesc » Mon Feb 10, 2020 2:39 pm

Can I add my name to list of people declaring an interest in obtaining one Raspberry Pi to 1Mhz interface

Regards

Chris
BBC B+ 128K

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tone76
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Re: New Raspberry Pi to 1MHz bus interface

Post by tone76 » Mon Feb 10, 2020 5:50 pm

KenLowe wrote:
Mon Feb 10, 2020 12:55 pm
Ok folks, I've placed an order for a 2nd batch of boards. I'm still not taking orders yet, but assuming they work as expected, then the following is the list of noted interest in the order I received it. If you think I've missed your name out, or if you would like your name added, please let me know, and I'll update this list.
Cheers Ken.

BTW: if you could upgrade my expression of interest to a 1MHz bus interface and a tube adapter, that would be great. :) although depending on price I may need to consider 2 of each ... especially if soldering is involved ... don't ask ...
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KenLowe
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Re: New Raspberry Pi to 1MHz bus interface

Post by KenLowe » Tue Feb 11, 2020 8:51 am

tone76 wrote:
Mon Feb 10, 2020 5:50 pm
BTW: if you could upgrade my expression of interest to a 1MHz bus interface and a tube adapter, that would be great. :) although depending on price I may need to consider 2 of each ... especially if soldering is involved ... don't ask ...
Updated to one of each. No soldering required. Should work straight out of the packaging :D.

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marcusjambler
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Re: New Raspberry Pi to 1MHz bus interface

Post by marcusjambler » Tue Feb 11, 2020 10:38 am

Hi Ken

I'd like a tube interface as well please :D

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Re: New Raspberry Pi to 1MHz bus interface

Post by aotta » Tue Feb 11, 2020 4:10 pm

Ken, count me for a Tube interface too, i've got a couple but i'd like to test your one!

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KenLowe
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Re: New Raspberry Pi to 1MHz bus interface

Post by KenLowe » Fri Feb 21, 2020 5:48 pm

KenLowe wrote:
Mon Feb 10, 2020 12:55 pm
Ok folks, I've placed an order for a 2nd batch of boards.
Unfortunately board manufacturing has been severely disrupted by the Coronavirus outbreak. The PCBs have all been manufactured, but the SMT assembly is still outstanding. Could be another couple of weeks yet before that's done, and then a further couple of weeks for delivery. I'll provide a further update once the SMT assembly is complete.

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crowly
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Re: New Raspberry Pi to 1MHz bus interface

Post by crowly » Fri Feb 21, 2020 6:57 pm

If I could add my name to the list, that would be great.

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Re: New Raspberry Pi to 1MHz bus interface

Post by DamienSturdy » Sun Feb 23, 2020 12:10 pm

Stuff me on the list for me please if that's OK? Got a niceittle project on the go with a Master, this is exciting to play with!

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Re: New Raspberry Pi to 1MHz bus interface

Post by egel » Sun Feb 23, 2020 3:51 pm

If I could add my name to the list too? That might be useful for my hard drive for z80 copro.

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KenLowe
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Re: New Raspberry Pi to 1MHz bus interface

Post by KenLowe » Sat Mar 14, 2020 1:35 pm

Ok folks, time for an update. I received the boards earlier this week, but there's still an issue with the sound quality that I'm trying to work through, with help from a couple of others on this site. The issue doesn't seem to affect the SCSI drive operation, but I've not done a huge amount of testing on this, so I'm reluctant to offer these for sale yet. Please bear with me...

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Re: New Raspberry Pi to 1MHz bus interface

Post by aotta » Sun Mar 15, 2020 9:40 am

Thank you for the update!
anyway, i am interested in the interface as a beebscsi replacement, so if you want to sell one at this stage, i'm ready!

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DaveLecky
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Re: New Raspberry Pi to 1MHz bus interface

Post by DaveLecky » Sun Mar 15, 2020 6:38 pm

Hi there,

Could I order a Tube interface please, when available.

Thanks

Dave
Electron Plus 3 and plus 1, AP6 and Home made MMFS PP SD interface
Electron Plus 1 Pres AP3/4 with drive
Beeb issue 7 with IFEL 16 socket Rom/Ram board, IFEL SD card, Floppy interface
Master 128, BooBip multi OS,IFEL SD card
Cumana drives,Adder Programmer

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KenLowe
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Re: New Raspberry Pi to 1MHz bus interface

Post by KenLowe » Sun Mar 15, 2020 6:59 pm

DaveLecky wrote:
Sun Mar 15, 2020 6:38 pm
Could I order a Tube interface please, when available.
Added to the list.

I've made some good progress today, and I've hopefully been able to get the audio working reliably. Unfortunately, the failure rate of the boards is higher than I initially anticipated, so I'm not going to be able to supply to everyone on the first list. As such, I'll be offering them in the order that they've been requested. Price will need to be adjusted to reflect the higher than anticipated failure rate, but I don't see it making a huge difference. Hopefully, in the coming days, I'll be able to make a post on this thread, pointing to a new thread in the For Sale section. In that thread I'll confirm the costs, and also provide a couple of options; primarily if you want a board that will fit directly under the computer, or if you want one that will be used externally (one will have a female header that plugs directly into the 1MHz port, and the other will have a male header that a ribbon cable can be plugged into). I'll also offer a ribbon cable for those who want to use the external version.

Those who miss out on this initial batch, don't worry. I've placed a further order, so there should be plenty for everyone. Hopefully won't see too many delays with the ongoing Covid related lock downs, but the new boards are probably at least one month away.
Last edited by KenLowe on Mon Mar 16, 2020 12:58 pm, edited 1 time in total.

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KenLowe
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Re: New Raspberry Pi to 1MHz bus interface

Post by KenLowe » Sun Mar 15, 2020 11:52 pm

Here's a couple of photos showing the Tube level shifter sitting next to the 1MHz level shifter. Note how the 1MHz board is being powered via a specific power connector on the Tube level shifter board. This keeps the User port free for other uses (eg SD based file system):
20200315_231924.jpg
Level shifters
20200315_232055.jpg
with Raspberry Pi Zeros attached
You may notice that the front edge of the RPi Zero sits very close to the edge of the case. This is because I had to reduce the overall size of the level shifter boards to make them easier to fit under the Master case. It was a bit of a compromise.

Dominic (dp11) has been busy on the software side, and earlier this evening uploaded a new version of the Pi1MHz firmware to his Github page. Both SCSI drive (via ADFS) and Music5000 are working well with this firmware, with Music5000 playing audio quite clearly through the beeb speaker. With this redesigned level shifter board, the noise issue I was experiencing with the earlier board is now eliminated. PiTubeDirect is also working well on the Tube side.

I've also got a Master set up with an external level shifter plugged into a RPi 3B+. This is also working well. I'll upload some photos tomorrow showing this setup, and a couple of other photos with the Tube level shifter sitting next to the 1MHz level shifter under the Master case.

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KenLowe
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Re: New Raspberry Pi to 1MHz bus interface

Post by KenLowe » Mon Mar 16, 2020 9:33 pm

As promised, here's a couple of photos of the external version of the 1MHz level shifter. I'll probably drop the power socket in the production versions, as the level shifter should be powered from the RPi 3B+:
20200316_211046.jpg
External 1MHz level shifter
20200316_210958.jpg
Plugged into a RPi 3B+
20200316_210926.jpg
And with the case closed

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KenLowe
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Re: New Raspberry Pi to 1MHz bus interface

Post by KenLowe » Tue Mar 17, 2020 10:00 pm

Finally, here's a couple of photos with level shifters installed in the Master. Although the depth of the Tube & 1MHz level shifter boards are exactly the same, the 40 pin socket for the Tube board is slightly (approx 1.5mm) deeper than the equivalent 34 pin socket on the 1MHz board, so overall, the board is slightly deeper, making it more difficult plug into the computer. I've ordered up some different 40 pin sockets, which are hopefully not as deep.
20200316_214752.jpg
Tube & 1MHz Level Shifters in Master
20200316_215030.jpg
and with RPis Installed

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KenLowe
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Re: New Raspberry Pi to 1MHz bus interface

Post by KenLowe » Tue Mar 17, 2020 11:30 pm

I have now made a post in the For Sale section. Please make any future notes of interest in that thread.

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Re: New Raspberry Pi to 1MHz bus interface

Post by Wheel_nut » Sat Mar 21, 2020 12:02 pm

I hope this isn't a silly question, or one that has been answered before, but can either the Tube or 1MHz bus interface be used with the Original Raspberry Pi 1B or 2B?

I ask because I have a bunch of these which I bought for my daughter who is a Teacher, to use in extra-curricular RPi Clubs to get Primary School children into coding. She has now upgraded her Raspberry Pis and I am loathe to waste the fully functional RPi 1Bs.
#1 BBC Model B Issue 7 + 1770 DFS + Dual TEAC Floppy
#2 BBC Model B Issue 7 + 8271 DFS + Dual Floppy + Speech + PiTubeDirect on KenLowe's Tube Level Shifter
#3 BBC Model B Issue 7 + 8271 DFS + Cumana Single Floppy

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BigEd
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Re: New Raspberry Pi to 1MHz bus interface

Post by BigEd » Sat Mar 21, 2020 1:02 pm

(Are those early Pi with a 26 way header, or with a 40 way header?)

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