I’m trying to understand what standards - if any - the Reform uses for the processor module. I have never owned a laptop that isn’t some sort of regular x86 PC, so I’m curious to know what I’ll be dealing with when my Reform lands on my porch.
From what I’ve been able to read and deduce, this is what I understand:
The motherboard connector was designed for the NXP i.MX 8M system-on-module because that’s what the Reform originally came with. So it’s not so much a standard as a standard created by NXP, which has been adopted by MNT Research for the Reform and the Pocket Reform.
MNT Research sells adapters to connect certain SoMs that use different manufacturer pinouts, e.g. Raspberry Pi CM4.
The RCORE RK3588 SoM is a clean-sheet MNT Research design that uses the NXP pinout natively, since I see a screenshot of a PCB layout and it’s not sold with an adapter.
I don’t know the origin of the SoM pinout the Reform uses - if its originally from NXP (SoC maker) or Boundary Devices (who makes the NXP SoM modules).
The benefit of this particular pinout is its easy to manufacturer, a 200 pin sodimm connection requires no special connectors (unlike the CM4 hirose connectors).
The RCM4 adapter is compatible with several CM4 pinout modules (BPI-CM4, Raspi CM4, and possibly others). The main drawback of the RCM4 adapter board is that the CM4 pinout does not expose the same functionality as the 200 pin sodimm, so features are often lost (extra pcie lanes, usb 3.0, etc. - see the modularity table)
Several modules have been made in partnership with Boundary Devices or by MNT for the Reform specifically (the LS1028A, rk3588, and the FPGA modules).
As far as I can recall, the connector originated with Boundary Devices, but it was well-documented so it was adopted. There’s a template for module creation in the MNT repo with more information: Reform / Reform SoM Template · GitLab
FYI RCORE is an adapted T-Firefly SoM on an MNT-designed carrier board.
Yes I totally see the appeal. But I guess the takeaway is that there isn’t really any sort of de-facto standard for SoM connectors - which is what I was originally wondering - meaning any new module has to be adapted for use in MNT machine in some way or other.
Nice!
I see on that template that there are 3 UARTs. UART3 is used to talk to the system controller apparently, but UART1 and 2 seem unused, and from what I see on the RK3588 module pinout, they’re connected. Hmm… I wonder if they’ll show up as /dev/tty* in Linux: I can always use UART and RS232/422 ports.
Also, sadly, it looks like the JTAG pins aren’t connected. Too bad, that would have made debugging really quite handy.
I can’t wait to get my hands on my Reform: the more I read, the more fun it looks like I’m gonna have with it
