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+--- Thread: New Model Development Updates (/thread-449.html)
RE: New Model Development Updates - MbeeTech - 09-01-2025
Happy new year everyone.
Building up the new boards has gone well.
Today I've built 2 of the new FPGA boards and finished off the main board build.
As far as testing goes, so far I've only confirmed that the power supply section of the main board works as expected.
Next I have to do some work on the FPGA logic to re-specify the physical constraints because of pin allocation changes.
I also have to do some work on the firmware (board bring-up code for the MC68SZ328) as I've changed a couple of chip selects
and have moved from Static RAM to SDRAM for the main memory.
Here's a pic of the fully built 64 key model :
In preparation for production I've also created a programming jig for the FPGA board to easily access the JTAG port of the FPGA.
JTAG is used to program the onboard SPI flash for the FPGA's logic design, and the jig will also make it easier to program the BOOT flash
for the system firmware prior to shipping. I've designed it into the same case used for our UpScaling video converters.
Here's a pic (with a couple of parts still missing) :
It has HDMI out, sound, SDcard and USB ports for KB & Mouse.
RE: New Model Development Updates - MbeeTech - 11-01-2025
The PCB for the model in the 256TC case has just been completed.
It is essentially the same circuit, but with the keyboard section removed, a LED board added and some
extra mounting holes to fit it in the case with.
Here's a preview :
The LED board breaks out from the main board & is connected by a small cable to the back of the 98 key keyboard.
RE: New Model Development Updates - Mr Lurch - 11-01-2025
(11-01-2025, 01:08 PM)MbeeTech Wrote: The PCB for the model in the 256TC case has just been completed.
It is essentially the same circuit, but with the keyboard section removed, a LED board added and some
extra mounting holes to fit it in the case with.
Here's a preview :
The LED board breaks out from the main board & is connected by a small cable to the back of the 98 key keyboard.
These are for the handful of genuine cases you still have yeah?
RE: New Model Development Updates - MbeeTech - 11-01-2025
(11-01-2025, 05:06 PM)Mr Lurch Wrote: These are for the handful of genuine cases you still have yeah?
If you call 1000-1200 cases a handful, yes.
If it was only a handful I would not have bothered with designing the new keyboard to suit.
RE: New Model Development Updates - CheshireNoir - 13-01-2025
Wow. That is a LOT of cases! If I ever design a single board computer, I'll have to target that form factor :-D
JOhn
RE: New Model Development Updates - MbeeTech - 13-01-2025
(13-01-2025, 03:43 PM)CheshireNoir Wrote: Wow. That is a LOT of cases!
It does sound a lot, but considering the Spectrum Next etc., it's probably not really a lot. :-)
RE: New Model Development Updates - Mr Lurch - 14-01-2025
(11-01-2025, 05:20 PM)MbeeTech Wrote:(11-01-2025, 05:06 PM)Mr Lurch Wrote: These are for the handful of genuine cases you still have yeah?
If you call 1000-1200 cases a handful, yes.
If it was only a handful I would not have bothered with designing the new keyboard to suit.
I had no idea it was that many. Nice.
RE: New Model Development Updates - MbeeTech - 01-02-2025
The new [production] versions of the boards for the 2 models have lots of changes from the earlier prototypes, and in particular
the FPGA board. As a result there has been quite a bit of firmware and FPGA logic changes that needed to be made before I could test out
the new versions.
For example, the on the FPGA board the changes have been:
2Mb SRAM for main memory is now 32Mb SDRAM (on a different chip select from the MC68SZ328 processor with more initialisation needed)
Memory addressing changes, with different configuration requirements etc. etc.
Addition of Flash ROM to boot from (rather than the small embedded boot rom within the FPGA logic.
HDMI & I2S sound chips onboard now.
This week has been spent making all those changes, and I'm very pleased to say that the new version of the FPGA board is working really well.
Most of the hardware on the board is now proven out (with the exception of the Keyboard, Mouse & I2S sound interfaces).
Below is a picture of the new FPGA board in the 'Test Fixture / Production Programming jig' with power in and HDMI out attached.
Included in the new design is a way to reload the boot flash if it ever fails during a power off event during an update.
In the pic you can see nice crisp screen display, testing the FLASH ROM, reading the flash image in from SDcard etc.
Very happy with the progress. More to come.
RE: New Model Development Updates - MbeeTech - 06-02-2025
Boards have arrived for the 256TC cased model.
Note that I've removed the name of the new model from the photos.
All will be revealed at the official launch.
Back panel :
Main PCB :
Assembled keyboard (key caps due in last week Feb) :
RE: New Model Development Updates - MbeeTech - 13-02-2025
Completed the Flash ROM update utility which loads the system firmware into the Flash ROM for the MC68SZ328 to execute on power up.
It takes a ROM image file from the SDcard, blank checks the Flash rom & erases it as needed, then programs the image into the device.
Next job was to finalise all the changes to the FPGA pinout & logic, and update the firmware accordingly.
So far so good. Both new models boot Microbee disk images:
64 key model 98 key model