P2DIP40 (for existing P1 sockets) and P2DIL80 (for new designs) - updated schematic and USB case

Tubular

I've been working for some time on some DIP40-centric P2 designs quite similar to what Dave Hein was proposing with his P2 QUIP concept.

If we're doing a video conference tomorrow then I can share details then, otherwise post pics here

Cluso99

Sounds interesting

BTW Forum problem has dual posts

Publison

I deleted the duplicate

Tubular

Thanks Jim. Made a phone call in the middle and forgot I already posted it. Much appreciated

Tubular

Here's an overhead plan view of the board when configured as P2DIL80

In this configuration there are two 40 pin DIL headers, like used with PC104, Pi and other systems (ie common), connecting the PCB down to a host pcb underneath.

You can think of two counterclockwise circles of I/O
- The inner circle is P2 port A (P0..31) and matches the format of the Prop1 (P8x32A-D40)
- The outer circle is P2 port B (P32..63), including pins to match up with 2 Mikrobus sockets. There are also SPI, Prop Plug, Cascade pins in this circle.

There are a couple of pins marked NC, these are not used (pulled out/cut) due to where the P2 is positioned underneath the board.

Tubular

Here's a fancy ISO drawing of P2DIL80

I'll come back to this and make the text a bit thinner/more legible later

Tubular

Regarding P2DIP40,

This uses the same pcb, but in a slightly different way. There are only single rows connected down to the board below. Pins P16 through P31 mount in an adjacent row 0.1" closer, to provide the correct overall 600 mil spacing to fit the standard P1 Dip40 socket.

I'll post an iso drawing showing this later

rogloh

It looks pretty interesting Lachlan. I'll have to watch the YT later to hear more about it once it's posted. One thing I realized with the Mikrobus wiring on your diagrams is that it's rotationally symmetric on your board, but any newly designed custom Microbus pin compatible boards using 8 bit P2 groups like 8 HDMI pins or 8 common data bus pins for memory would need to be installed on one side only (to consistently obtain the 8 bit streamer/HDMI group in the P2 group). Either that or build two variants of the boards one for each end which is not so practical. Not going to be an issue for all the existing Mikrobus boards of course with simple SPI/I2C/ADC/GPIO interfaces. The other way to solve it is to rearrange the wiring to assign to Mikrobus pins in this order P32..P39,P40..P43 and for the other end P48-P55,P44..P47, but it will mess up your nice existing sequential order (if that matters), and might need more signal crossings on the board.

Cluso99

Looks interesting Lachlan. Missed zoom this morning so waiting for the video on youtube to check it out.

Tubular

Yeah its a pain but I've come to embrace it this way on my Clickstart 6 breakout

Two Mikrobus sockets have full 12 pin "untangled" wiring to P2
- P32..43 for Hyperram, bus on P32..39
- P44..55 for comms eg FT2232H, later we can make more compact or ESP32 S2 options etc

Four Mikrobus sockets with 8 pin slighly muxed
- I2C shares SPI pins like on the Mikroe dev boards (saves 2 pins)
- INT, PWM, AN are resistively shared into a single pin (also saves 2 pins)
- RX, TX, RST, CS and either MISO or MOSI are 1:1 mapped (not shared)

Dave Hein

I'm looking forward to seeing your progress on this. When do you think you'll have working hardware?

Tubular

We're aiming for Oct 28th, there's another presentation to give on that date

Tubular

I'm working on a P2DIP40 variant that gets P24 back (so all port A, P0~31 gpio are present on the inner 0.6" loop, for legacy P1 compatibility.

This is designed to fit in a hammond 1551USB3 case, with the male USB A plug protruding (so it can plug directly into a PC, cable is optional

There are still 2 Mikrobus headers

Tubular

Here's a work-in-progress schematic

jmg

Tubular wrote: »

This is designed to fit in a hammond 1551USB3 case, with the male USB A plug protruding (so it can plug directly into a PC, cable is optional

Looks nice, the plastic case option has appeal.
What USB connection is planned ? An EFM8UB3 ?
You might be able to fit SMD pads on the DIP40 rear side skipped pins, to give more choices ?

Tubular

I'd like to find a way to have a modular footprint, so we can accommodate various options including your efm8ub3, esp32 s2/s3. One way might be to put a footprint down for a largish chip, eg FT231X, or even FT232 if it fits, then make small footprint compatable adapters that can be placed there.

jmg

Tubular wrote: »

I'd like to find a way to have a modular footprint, so we can accommodate various options including your efm8ub3, esp32 s2/s3. One way might be to put a footprint down for a largish chip, eg FT231X, or even FT232 if it fits, then make small footprint compatable adapters that can be placed there.

I managed to up-size the UB3 footprint on P2D2Pi to QSOP24, but that's a larger PCB than your smaller 1551USB3 case, which may only allow fit of the smaller QFN20 ?

hinv

Tubular wrote: »

Here's a work-in-progress schematic

Wow. That looks beautiful!

hinv

Tubular wrote: »

Here's an overhead plan view of the board when configured as P2DIL80

In this configuration there are two 40 pin DIL headers, like used with PC104, Pi and other systems (ie common), connecting the PCB down to a host pcb underneath.

You can think of two counterclockwise circles of I/O
- The inner circle is P2 port A (P0..31) and matches the format of the Prop1 (P8x32A-D40)
- The outer circle is P2 port B (P32..63), including pins to match up with 2 Mikrobus sockets. There are also SPI, Prop Plug, Cascade pins in this circle.

There are a couple of pins marked NC, these are not used (pulled out/cut) due to where the P2 is positioned underneath the board.

I really like this form factor, and they were cheap, so I got a few of them.
https://en.wikipedia.org/wiki/CHIP_(computer)
Maybe you could even use the existing DIP's for HDMI or VGA?

Tubular

oh yeah I remember the CHIPs now, but had forgotten.
Looking at the form factor, they are quite similar to the DE0-Nano fpga boards we used for prototyping the P2

Yes, you probably could use the existing dips for HDMI or Vga. What you really want is more like a dip-44, each quadrant would have 5V - P0 - P1 - P2 - P3 - P4 - P5 - P6 - P7 - GND, so you could do HDMI, VGA or USB, but need a 3v3 regulator for anything else

I'll pm you a link to something else that might be of interest

Thanks for your kind words about the schematic. I'm still working on it. Also, it looks funky when rotated 45 degree iso