BeagleY-AI

Overview

BeagleY-AI is a computational platform powered by TI AM67A (J722S) SoC, which is targeted for automotive applications.

Hardware

BeagleY-AI is powered by TI AM67A (J722S) SoC, which has two domains (Main, MCU). This document gives overview of Zephyr running on both Cortex R5.

L1 Memory System

BeagleY-AI defaults to single-core mode for the R5 subsystem. Changes in that will impact the L1 memory system configuration.

32KB instruction cache
32KB data cache
64KB tightly-coupled memory (TCM) * 32KB TCMA * 32KB TCMB

Region Address Translation

The RAT module performs a region based address translation. It translates a 32-bit input address into a 36-bit output address. Any input transaction that starts inside of a programmed region will have its address translated, if the region is enabled.

VIM Interrupt Controller

The VIM aggregates device interrupts and sends them to the R5F CPU(s). The VIM module supports 512 interrupt inputs per R5F core. Each interrupt can be either a level or a pulse (both active-high). The VIM has two interrupt outputs per core IRQ and FIQ.

Supported Features

The board configuration supports a console UART via the HAT header pins. Future versions will also support a console over RPmsg.

Interface	Controller	Driver/Component
UART	on-chip	serial port-polling serial port-interrupt

Other hardware features are currently not supported.

The default configuration can be found in the defconfig file.

Future configurations will add support for GPIO, I2C, SPI, etc.

Running Zephyr

The AM67A does not have a separate flash for the R5 core. Because of this an A53 core has to load the program for the R5 core to the right memory address, set the PC and start the processor. This can be done from Linux on the A53 core via remoteproc.

This is the memory mapping from A53 to the memory usable by the R5. Note that the R5 core always sees its local TCMA at address 0x00000000 and its TCMB0 at address 0x41010000.

The A53 Linux configuration allocates a region in DDR that is shared with the R5. The amount of the allocation can be changed in the Linux device tree. Note that BeagleY-AI has 4GB of DDR.

Region	Addr from A53	MAIN R5F	Size
ATCM	0x0078400000	0x0000000000	32KB
BTCM	0x0078500000	0x0041010000	32KB
DDR Shared Region	0x00A2000000	0x00A2000000	16MB

Region	Addr from A53	MCU R5F	Size
ATCM	0x0079000000	0x0000000000	32KB
BTCM	0x0079020000	0x0041010000	32KB
DDR Shared Region	0x00A1000000	0x00A1000000	16MB

Steps to run the image

Here is an example for the Hello World application targeting the MAIN domain Cortex R5F on BeagleY-AI:

# From the root of the zephyr repository
west build -b beagley_ai/j722s/main_r5f0_0 samples/hello_world

For the MCU domain Cortex R5F on BeagleY-AI:

# From the root of the zephyr repository
west build -b beagley_ai/j722s/mcu_r5f0_0 samples/hello_world

To load the image:

Copy Zephyr image to the /lib/firmware/ directory.
cp build/zephyr/zephyr.elf /lib/firmware/

Ensure the Core is not running.
echo stop > /dev/remoteproc/am67a-{main,mcu}-r5f0_0/state

Configuring the image name to the remoteproc module.
echo zephyr.elf > /dev/remoteproc/am67a-{main,mcu}-r5f0_0/firmware

Once the image name is configured, send the start command.
echo start > /dev/remoteproc/am67a-{main,mcu}-r5f0_0/state

Console

The Zephyr on BeagleY-AI Cortex-R5F uses UART 1 (HAT pins 8-TX, 10-RX) as console.