New Raspberry Pi to 1MHz bus interface

for bbc micro/electron hardware, peripherals & programming issues (NOT emulators!)
dp11
Posts: 969
Joined: Sun Aug 12, 2012 8:47 pm
Contact:

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.

User avatar
KenLowe
Posts: 853
Joined: Mon Oct 18, 2004 4:35 pm
Location: Scotland
Contact:

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.

User avatar
KenLowe
Posts: 853
Joined: Mon Oct 18, 2004 4:35 pm
Location: Scotland
Contact:

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.

User avatar
KenLowe
Posts: 853
Joined: Mon Oct 18, 2004 4:35 pm
Location: Scotland
Contact:

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.

aotta
Posts: 197
Joined: Fri May 26, 2017 8:57 am
Location: Italy
Contact:

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

User avatar
IanB
Posts: 431
Joined: Sun Sep 04, 2011 7:28 pm
Location: South Wales
Contact:

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.

th3bar0n
Posts: 10
Joined: Tue Apr 26, 2016 8:33 pm
Contact:

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!

User avatar
KenLowe
Posts: 853
Joined: Mon Oct 18, 2004 4:35 pm
Location: Scotland
Contact:

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
Posts: 16
Joined: Thu Jun 28, 2012 6:17 pm
Location: Manchester
Contact:

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

User avatar
tone76
Posts: 17
Joined: Mon Feb 10, 2020 10:35 am
Location: The Colonies
Contact:

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. :)
I didn't choose the Acorn life, the Acorn life chose me.

User avatar
KenLowe
Posts: 853
Joined: Mon Oct 18, 2004 4:35 pm
Location: Scotland
Contact:

Re: New Raspberry Pi to 1MHz bus interface

Post by KenLowe » 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.

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 accounted for

Code: Select all

User		1MHz	Tube
----------------------------
tucker		1	
marcusjambler	1	1
tricky		1	
mr-macrisc	1	
th3bar0n	2	2
Stewie66	1	
CJS		1	
awilliams	1	
markrwj		1	
rharper		1	
BCCweirdo	1	
Rod C		1	
Alan00		2	
roganjosh	1	
Remklep		1	
1024MAK		2	
aotta		2	1
IanB		2	2
mph1708		2	
tone76		1	1
Boydie		2	1

Batch 3 - To be ordered after I receive Batch 2

Code: Select all

User		1MHz	Tube
----------------------------
shakesc		1
crowly		1
DamienSturdy	1
egel		1
jimmy		1	1
Last edited by KenLowe on Mon Feb 24, 2020 7:14 pm, edited 8 times in total.

shakesc
Posts: 23
Joined: Tue Apr 24, 2018 2:34 pm
Contact:

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

User avatar
tone76
Posts: 17
Joined: Mon Feb 10, 2020 10:35 am
Location: The Colonies
Contact:

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 ...
I didn't choose the Acorn life, the Acorn life chose me.

User avatar
KenLowe
Posts: 853
Joined: Mon Oct 18, 2004 4:35 pm
Location: Scotland
Contact:

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.

User avatar
marcusjambler
Posts: 728
Joined: Mon May 22, 2017 11:20 am
Location: Bradford
Contact:

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

aotta
Posts: 197
Joined: Fri May 26, 2017 8:57 am
Location: Italy
Contact:

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!

User avatar
KenLowe
Posts: 853
Joined: Mon Oct 18, 2004 4:35 pm
Location: Scotland
Contact:

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.

User avatar
crowly
Posts: 22
Joined: Wed Sep 21, 2011 3:05 pm
Location: Sheffield
Contact:

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.

DamienSturdy
Posts: 2
Joined: Tue Jul 18, 2017 6:13 pm
Contact:

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!

User avatar
egel
Posts: 24
Joined: Mon Nov 25, 2019 1:10 pm
Location: Almere, Flevoland, The Netherlands
Contact:

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.

Post Reply