Chris Gammell and Dave Jones' voices span the chasm of thousands of miles each and every week to speak to each other and industry experts about where the field of electronics is moving. Whether it be a late breaking story about a large semiconductor manufacturer, a new piece of must-have test equipment or just talking through recent issues with their circuit designs, Chris and Dave try to make electronics more accessible for the listeners. Most importantly, they try and make the field of electronics more fun. Guests range from advanced hobbyists working on exciting new projects up through C-level executives at a variety of relevant and innovative companies. Tune in to learn more about electronics and then join the conversation! Visit The Amp Hour website for our back catalog of 150+ episodes.
https://theamphour.com
#648 – The RP1 and beyond with the Raspberry Pi Hardware team
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