Firmware engineer Jonathan Clark has been arduous at work unlocking the secrets and techniques of Raspberry Pi’s RP3A0 system-on-chip, discovered on the Raspberry Pi Zero 2 W single-board laptop — with a view to utilizing the half in his personal board designs.
“This [repository] accommodates my makes an attempt at reverse-engineering the RP3A0 SoC from the Raspberry Pi Zero 2 W so I can place it by myself PCB,” Clark explains. “I plan to ultimately use this in one other venture, however for now I would like a proof of idea. I made a decision to take advantage of cursed factor I may consider, [a Raspberry] Pi Pico sized board, however with a full Raspberry Pi processor on it. It has principally the identical pinout as a [Raspberry] Pi Pico, all of the GPIOs [General-Purpose Input/Output pins] that match up are in the identical place. HDMI is sketchy, there is no Wi-Fi, and USB [Type]-C is a bit bizarre, but it surely boots and I can get it on-line.”
Raspberry Pi’s in-house RP3A0 system-on-chip has been laid naked, because of a formidable effort in reverse engineering. (📷: Jonathan Clark)
Clark’s mission started after seeing an X-ray picture of the Raspberry Pi Zero 2 W and its RP3A0 system-on-chip, a compact 0.65mm-pitch developed by and solely out there to Raspberry Pi. It isn’t a component you should buy with out it coming hooked up to considered one of Raspberry Pi’s single-board computer systems, however that did not cease Clark wanting to place one on his personal board.
“There’s one other venture I have been engaged on for years (that I will in all probability doc in some unspecified time in the future sooner or later), however I needed so as to add a Linux[-capable] processor to it,” Clark explains. “Nevertheless it is fairly house constrained and I did not wish to should do traces for DDR [memory], so I used to be searching for an SoC that had a good quantity of RAM baked in, or a good SoM [System-on-Module]. Sadly, most SoMs I discovered have components on the opposite aspect as effectively, that means I would should have a cutout in no matter board I used to be placing it on.”
For the exact same cause of house saving, Raspberry Pi’s RP3A0 consists of each the processor and RAM in a single half — so Clark snagged a Raspberry Pi Zero 2 W and desoldered its parts earlier than sanding the board right down to seize imagery of every of its six layers. This supplied a technique to see precisely how every pin of the chip was wired up — which, in flip, allowed Clark to design the RP3A0 Pico, which is successfully a Raspberry Pi Zero 2 in a Raspberry Pi Pico type issue powered by a desoldered and reballed RP3A0.
Clark sanded a Raspberry Pi Zero 2 W into its particular person layers (above), to be able to design a Raspberry Pi Pico-like different (high). (📷: Jonathan Clark)
Whereas Clark has supplied a wealth of fabric for individuals who wish to comply with in his footsteps, he additionally has one key bit of recommendation: “This was a silly thought and also you in all probability should not do it,” he warns. “There are heaps of different Linux SoCs you need to use, an particularly ones that are not a 21×21 BGA system with no public documentation. It is also not tremendous simple to solder, so that you may trash a pair components making an attempt to get it proper.”
For individuals who aren’t postpone by that warning, the venture is documented in full on GitHub together with Altium venture information for the RP3A0 Pico board and a component library for the chip itself.
