Raspberry Pi Foundation has released the datasheet for the RP1 chip used in the Rospberry Pi 5 board, which handles I/O functions such as GPIO, SDIO, USB, camera, display, and Ethernet. The document is currently only a draft, but the foundation suggests that it may help developers port their operating systems.
The datasheet showcases the internal components of RP1, with the main component being the bus fabric that connects the main CPU to the various I/O interfaces. Inside, there are also two Cortex-M3 CPUs for configuring the chip’s operations, along with a boot ROM and a 64kB RAM that collaborates with the different devices on the chip.
The goal of RP1 is to separate the I/O portion using a cost-efficient production process compared to the main chip. However, it still remains compatible with the I/O of the original CPU. The team mentioned the difficulties faced, such as selecting the substrate material, which required cost-cutting measures by utilizing a 2-layer design, making the design process more challenging but ultimately successful.
TLDR: Raspberry Pi Foundation released a draft datasheet for the RP1 chip used in the Rospberry Pi 5 board, which handles various I/O functions. The document aims to assist developers in porting operating systems. The datasheet highlights the internal components, including the main bus fabric and two Cortex-M3 CPUs, along with a boot ROM and 64kB RAM. The goal of RP1 is to separate I/O functions while maintaining compatibility with the original CPU. The design process faced challenges, such as substrate selection, but achieved success with a 2-layer design.