#648 – The RP1 and beyond with the Raspberry Pi Hardware team

Oct 23, 2023

James Adams and Liam Fraser from the Raspberry Pi Hardware team discuss the RP1 chip, RP2040 updates, sourcing chips, IP block updates, prototyping on FPGAs, openness in Raspberry Pi's hardware, and hidden signatures on the Raspberry Pi board.

Ask episode

Chapters

Transcript

Episode notes

Introduction

00:00 • 3min

Building a Chip Design Team for Raspberry Pi

02:56 • 22min

Aggregators, Wafers, and Chip Allocation

24:48 • 9min

Raspberry Pi servers, encrypted disks, and buying IP for controllers

33:45 • 5min

Prototyping for FPGAs and FPGA-based testing

38:24 • 5min

Openness in Raspberry Pi's Hardware

43:17 • 22min

Hidden Signatures and Future Raspberry Pi Models

01:05:30 • 3min

Welcome back James Adams and Liam Fraser

The RP1 is the new custom silicon on the Raspberry Pi 5 that is the helper chip to the Broadcom part onboard
The HW team was last on the show in 2021 talking about the RP2040
They have been working on the RP1 since 2015
It’s a small team, especially compared to other companies doing custom silicon.
RP2040 update
Scripting to reconfigure the silicon clocks/blocks
Are they making other chips?
Divvy-ing up duties for silicon
Broadcom is making the processor and took input for this latest
Dialog/Renesas do the power chip on the RPi5
PIO
Chris gave an example of a board (the Ostentus) where the PIO is just listening for i2c messages and passing them up the stack.
Design goal was to do cycle by cycle processing
Someone on twitter having PIO talking to fiber transceivers
Sourcing and RP2040 availability
They get 20000 chips per wafer
Buying wafers a few at a time through IMEC, sometimes through TSMC directly
There are often small amounts of availability of “wafer starts”
TSMC40
IP block updates: USB 3 / Ethernet
Can do diffs on the verilog
Receiving high paid IP
Liam is the sysadmin / servers are on site
Buying from Synopsis
Stitching together IP
They list what version of the IP they’re using in the various sections of the datasheet.
Prototyping on FPGAs
Controller and Phy interface are exposed
ProFPGA system with daughtercards
Can’t run at full clock speed on FPGA
Digital vs analog simulation
Could someone (competitors) copy things?
As open as possible, being open where it provides value
Cost savings on the RP2040
Traditionally the “Southbridge” is the IO hub for computing, the Northbridge was the cache/memory (later subsumed into large CPUs)
2712 on RPi is 16 nm
This model of creating different generations of silicon but putting them all together is similar to chiplets but…on a PCB
There is a (hidden-ish) PIO in the RP1.
There will be more processing delays in RPI5 to deal with, but they won’t be noticable because Linux is already pretty not-real-time
Hoovering up more functions in one chip
Layout of connectors changed again
Pins are created to be well laid out on the PCB
RISC V foundation
The stack / ecosystem isnt as mature
James’ signature is under the USB3 connector
RPi5 is “the most raspberry pi raspberry pi” yet