This video tour shows you how to examine the Raspberry Pi RP2350 silicon chip in detail – by removing the case.
Pseudonymous YouTuber “electronupdate” has looked deeper than most into how Raspberry Pi’s new RP2350 microcontroller works – by peeling back the cover and taking pictures of the silicon underneath.
“The star of the show is the new RP2350,” writes electronupdate about its analysis. “A number of changes (from the RP2040), perhaps the most intriguing being two Arm (Cortex-)M33 cores or two RISC-V Hazard3 cores. There’s no question that Arm dominates the embedded processor space, but there is a challenger on the fringes: RISC-V. Rather than risk building a RISC-V product, they are cleverly betting both on their next chip, allowing the customer to switch between architectures if they want. This is a clever way to gauge market demand without incurring too much cost.”
While Raspberry Pi has shared a lot about the Raspberry Pi Pico 2 and the dual-architecture RP2350 microcontroller that powers it, the launch earlier this monththe company has not analyzed exactly what is inside that square black chip package. Electronupdate has taken up the challenge and decapsulated a chip that was unfortunately packaged in such a way that non-destructive imaging of the chip is impossible to analyze what is going on inside.
“Same 40nm process as the previous (Raspberry) Pi Pico (RP2040),” electronupdate notes in its analysis, which was brought to our attention by Adafruit“but the chip is a lot bigger. (It’s) a classic piece of design! The power supply is a buck-boost from Richtek. An interesting choice as it allows the assembly to run on a voltage of just 1.8V (maybe battery powered?)”
Other highlights of the analysis, which was complicated by the fact that the interesting parts were covered by a power distribution network that had to be carefully removed, include identifying reused blocks from the original RP2040 (the (RP2350) is very much an incremental design,” electronupdate speculates), an on-die voltage regulator (“I’m not entirely sure why they put a voltage regulator in there,” the YouTuber notes), the four analog-to-digital converters (ADCs), and the on-chip memory.
A shot taken after the first cap removal was disappointing, as most of the circuitry was hidden under a power distribution mesh. (📷: electronupdate)
The latter has been closely watched for a very good reason: the chance to win a cash prize. “(Raspberry Pi has) a competition running where I believe there is a small prize to be won if you can read a secret from the ROM,” says electronupdate, referring to a competition Presented at DEF CON 32 earlier this month. “A physical attack is actually a pretty successful approach, but we have to do selective metal removal, which is actually quite complicated, but I suspect that this way we could solve the mystery.”
The full tour of the chip can be found in the video embedded above and on the electronupdate YouTube channelFor further information please see in an accompanying blog post.
