10-12-2024, 04:07 PM
Update time.
Over the past few weeks both the FPGA board and main board have lots of revision and the designs are just about fully routed
for the new (and hopefully production) versions.
There is only a minor amount of routing of the FPGA board left, with only the connections from the HDMI transmitter chip to the SO-Dimm
edge connector left to route. This is a little tricky as it involves pushing and shoving existing routing to make way for a clear path for
the differential DVI signals and the I2C, HPD, and CEC signals on an inner layer of the PCB.
The Main PCB routing is done and just needs a bit of cleanup & checking over. It should be into the PCB fab house by Thursday.
Looking at the PCB from the front, you can see quite a number of changes.
The power supply section (far right) has been rationalized. The previous version had supplies for both 5v & 3.3v. Now the FPGA board
provides the 3.3v for the main board as well as for it's own requirements.
The audio output for the internal speaker has been re-designed to take the stereo line level output from the FPGA board's I2S sound
output and sum it into mono audio with a rear facing volume pot. The single bit from the PIO chip that provides the Microbee's normal sound output
now routes to the FPGA and gets combined with the dual sound (stereo) FIFO's before being sent out to both the HDMI transmitter (for sound
over HDMI) and the onboard stereo DAC that provides line level output to a rear jack.
As you'll see in the next couple of pictures, the 5 pin DIN socket that has been the connection for Power, Video and the cassette interface has been
retired and replaced. There are a number of reasons for that.
Firstly, it's a real pain to make the power supplies for the 5 Pin DIN.
Also, the normal monochrome video output is no longer supported. While some people might have monochrome monitors that suit, that is not
the case for most people, and although some TV's have AV inputs that work well enough, it's still not great.
The video output is now upscaled HDMI and that is provided via the new connector on the back panel. It is a much cleaner, sharper solution and most
people have a suitable monitor or TV with HDMI in. No more need for 15Khz capable monitors or external upscalers.
The cassette interface has been retained but the connection is now via a 3.5mm stereo plug for the die-hards who would still like to read and record to tape.
You'll also notice a USB connector has been added. It is for adding mouse functionality (only).
With the exception of the power switch, everything fits nicely in the Premium case if you have one. If choosing to use a Premium case
you can leave the power switch off and jumper the switch position. I'm looking into a 'premium style' case replacement design.
Of course the board is also designed for the 256TC case with the new keyboard, in which case the power switch will be included.
There probably more that I've not detailed here, but there you have it for now.
I think I mentioned earlier but the keycaps for both the 64 key [premium] layout and the 98 key new layout have been ordered.
The manufacturer has informed me that the 64 key sets will be shipped in January, and "fingers crossed" the 98 key layout caps
will be during February.
Over the past few weeks both the FPGA board and main board have lots of revision and the designs are just about fully routed
for the new (and hopefully production) versions.
There is only a minor amount of routing of the FPGA board left, with only the connections from the HDMI transmitter chip to the SO-Dimm
edge connector left to route. This is a little tricky as it involves pushing and shoving existing routing to make way for a clear path for
the differential DVI signals and the I2C, HPD, and CEC signals on an inner layer of the PCB.
The Main PCB routing is done and just needs a bit of cleanup & checking over. It should be into the PCB fab house by Thursday.
Looking at the PCB from the front, you can see quite a number of changes.
The power supply section (far right) has been rationalized. The previous version had supplies for both 5v & 3.3v. Now the FPGA board
provides the 3.3v for the main board as well as for it's own requirements.
The audio output for the internal speaker has been re-designed to take the stereo line level output from the FPGA board's I2S sound
output and sum it into mono audio with a rear facing volume pot. The single bit from the PIO chip that provides the Microbee's normal sound output
now routes to the FPGA and gets combined with the dual sound (stereo) FIFO's before being sent out to both the HDMI transmitter (for sound
over HDMI) and the onboard stereo DAC that provides line level output to a rear jack.
As you'll see in the next couple of pictures, the 5 pin DIN socket that has been the connection for Power, Video and the cassette interface has been
retired and replaced. There are a number of reasons for that.
Firstly, it's a real pain to make the power supplies for the 5 Pin DIN.
Also, the normal monochrome video output is no longer supported. While some people might have monochrome monitors that suit, that is not
the case for most people, and although some TV's have AV inputs that work well enough, it's still not great.
The video output is now upscaled HDMI and that is provided via the new connector on the back panel. It is a much cleaner, sharper solution and most
people have a suitable monitor or TV with HDMI in. No more need for 15Khz capable monitors or external upscalers.
The cassette interface has been retained but the connection is now via a 3.5mm stereo plug for the die-hards who would still like to read and record to tape.
You'll also notice a USB connector has been added. It is for adding mouse functionality (only).
With the exception of the power switch, everything fits nicely in the Premium case if you have one. If choosing to use a Premium case
you can leave the power switch off and jumper the switch position. I'm looking into a 'premium style' case replacement design.
Of course the board is also designed for the 256TC case with the new keyboard, in which case the power switch will be included.
There probably more that I've not detailed here, but there you have it for now.
I think I mentioned earlier but the keycaps for both the 64 key [premium] layout and the 98 key new layout have been ordered.
The manufacturer has informed me that the 64 key sets will be shipped in January, and "fingers crossed" the 98 key layout caps
will be during February.