The Undocumented Pi

From eLinux.org
Revision as of 11:44, 2 March 2020 by Elijah (talk | contribs) (PMIC: Add history, correct mistakes)
Jump to: navigation, search

Back to the Hub.


Resources:

Hardware & Peripherals:

Hardware and Hardware History.

Low-level Peripherals and Expansion Boards.

Screens, Cases and Other Peripherals.

Software & OS Distributions:

Software and Distributions

Documentation:

Documentation Page

The Undocumented Pi

Hardware

SoC

There is a nicely ordered table with all BCM2835_registers as found in the GPU code published by Broadcom. Unfortunately, the table does not quite match the SoC in the Raspberry Pi, but it's a good start. The sections below should serve as a companion to that table.

BCM2711

The BCM2711 does not have PLLH.

PMIC

The BCM2835 chip has an on-chip SMPS and an LDO for the LPDDR2 memory chip. RPi2 and RPi3 B use custom circuitry made of discrete components to do the power-up sequencing, including an NCP6343 chip (datasheet) at I²C address 0x1c. The RPi 3B+ and RPi 4B boards contain a MaxLinear MxL7704 (datasheet) at address 0x1d.

The PMIC is always on the system I²C bus (I2C8 on RPi4, I2C0 on all other devices).

Boot ROM

Firmware

Abbreviations

CM
Clock Manager
HSM
HDMI State Machine
OTP
One-Time Programmable (memory)