TMDS64EVM: First time using TMDS64EVM

Hello Seth,

What is a PRU core, and how does it relate to Ethernet? 

PRU cores are programmable, bare metal cores which are able to read and write processor pins with deterministic latency, faster than any other processor core sold by TI or any of our competitors.

In case you might want to use one PRU subsystem for PRU Ethernet and one PRU subsystem for custom programming, you can find more information in the brand-new
PRU Academy > What is the PRU, and what is the PRU good for?
https://dev.ti.com/tirex/explore/node?isTheia=false&node=A__AfYd0P3wI1CDis1g9k1nSQ__AM64-ACADEMY__WI1KRXP__LATEST 

Because PRU cores can read and write pins so quickly, you can use them to implement protocols in software, instead of needing to use a bunch of circuits to implement the peripheral interface. So PRU cores can do stuff like add additional UART, SPI, I2S, etc... and also add additional Ethernet ports.

Ethernet on AM64x: CPSW & PRU Ethernet

The AM64x can do up to 2 CPSW Ethernet ports, and up to 4 PRU Ethernet ports (2 ports per PRU_ICSSG subsystem). Because of pinmuxing conflicts, you can only use 5 of these Ethernet ports in a single design.

Ethernet with a PRU subsystem is different from Ethernet with the CPSW3G subsystem, because the CPSW is a bunch of hardware circuits, while PRU Ethernet is implemented in software. That also means that PRU Ethernet can be used for implementing industrial networking interfaces, like EtherCAT, Ethernet/IP, Profinet, Profibus, etc., without having to pay for an external ASIC to do the protocol for you.

More information on using Linux with Ethernet is in the Linux SDK docs:

PRU Ethernet
https://software-dl.ti.com/processor-sdk-linux/esd/AM64X/latest/exports/docs/linux/Foundational_Components/PRU-ICSS/Linux_Drivers/PRU_ICSSG_Ethernet.html
https://software-dl.ti.com/processor-sdk-linux/esd/AM64X/latest/exports/docs/linux/Foundational_Components/PRU-ICSS/Linux_Drivers/PRU_ICSSG_Ethernet_Switch.html
https://software-dl.ti.com/processor-sdk-linux/esd/AM64X/latest/exports/docs/linux/Foundational_Components/Kernel/Kernel_Drivers/Network/HSR_Offload.html
https://software-dl.ti.com/processor-sdk-linux/esd/AM64X/latest/exports/docs/linux/Foundational_Components/Kernel/Kernel_Drivers/Network/PRP_Offload.html

CPSW ethernet
https://software-dl.ti.com/processor-sdk-linux/esd/AM64X/latest/exports/docs/linux/Foundational_Components/Kernel/Kernel_Drivers/Network/CPSW-Ethernet.html

You can also control Ethernet from the R5F cores 

This is especially useful if you want to implement a slave-side Ethernet protocol on the AM64x, since Linux usually doesn't have the deterministic performance to act as an Ethernet slave.

Keep in mind that using Linux A53 + R5F controlling Ethernet will require some system-level design - if you need guidance on that in the future, you can create a separate e2e thread.

Please refer to the MCU+ SDK for "regular" Ethernet controlled by the R5F cores:
https://software-dl.ti.com/mcu-plus-sdk/esd/AM64X/latest/exports/docs/api_guide_am64x/NETWORKING.html

Please refer to the industrial communications SDK for the industrial communication protocols we discussed above:
https://www.ti.com/tool/download/INDUSTRIAL-COMMUNICATIONS-SDK-AM64X

Regards,

Nick

Regards,

Nick

Thank you for the reply. This is good information, but one point I failed to note is that this is a protoype for an aerospace application, and I am not able to use the SDK generated code due to customer/industry restrictions on COTS source code. I am going to need to do bare-metal development, both for the executive/scheduler processing on the A53, setup/execution of Ethernet transmit/receive processing on the PRU-ICSS, and the exchange of data between the two cores. Are there any manuals, tutorials or example code I could refer to for this sort of "ground up" development? 

Hello Seth,

We will be limited in the support we can offer on this forum - we can answer questions about TI software or TI hardware, but we cannot support custom code or OS development.

With that said, I know that multiple companies and third parties have used our MCU+ SDK (which has both FreeRTOS and bare metal drivers) as a starting point for developing their own custom RTOS or bare metal implementations.

I am reassigning your thread to another team member who is more familiar with R5F <--> PRU Ethernet. Is this "generic" Ethernet, or a specific Ethernet industrial communication protocol?

Regards,

Nick

I assumed there would be some limitation, so thank you for your candid reply. Pointing me in the right direction with the proper hardware ref manuals in hand to be succesful would be appreciated. This is for an AFDX implementation (Avionics Full-Duplex Switched Ethernet, which is formalized in ARINC-664p7 standard). Thanks again for any support you can provide.

For commercially supported RTOS and Ethernet Drivers on A53 - GHS Integrity, QNX and VxWorks are option with varying degree of support.

Seth Appleman said:

This is for an AFDX implementation (Avionics Full-Duplex Switched Ethernet, which is formalized in ARINC-664p7 standard)

This seems technically feasible to implement using PRU-ICSSG. Certification Requirements: Avionics applications require DO-254/DO-178C certification, which would need to be addressed for the ICSSG implementation, this looks to be the most challenging aspect in this project than implementing specific features like

1. • Virtual Link management
   • Redundancy handling
   • BAG enforcement
   • Sequence monitoring

.Other option is to refer to R5F enet lld application and port this to gcc toolchain from ti-arm-clang toolchain as well as refer to CPSW example here : mcupsdk-enet-lld/examples/enet_layer2_cpsw/am62x-sk/a53ss0-0_freertos at mcupsdk_next · TexasInstruments/mcupsdk-enet-lld

Can you please refer me to the sections in the AM6422 that would be relevent to this issue, or what manuals I would need to refer to in order to interact with the hardware on the PRU-ICSSG? That seems to be the key piece of information I have not yet found. I have the A53 core ref manual, but that doesn't deal  (from what I have seen so far) with how I would write code to intialize and use the PCR-ICSSG components. Also, how do I interface (Exchange data, etc) between code running on the A53 and code running on the PRU_ICSSG? Please point me to documentation that would allow me to write code from scratch, in addition to any existing examples proved by TI. Thanks!

Hello Seth,

Warning: this PRU code would be very complex

Before I point you to a bunch of resources, please keep in mind that what I am about to describe is an extremely complex programming project, where I will not be able to give you a lot of help. If this is a protocol where you can do all the programming in the R5F core, it may be easier to use CPSW as your Ethernet port. Then bare metal code on either R5F or A53 could send and receive Ethernet frames to and from the CPSW.

If you do end up needing to program the PRU cores for the custom Ethernet protocol, you may want to reach out to a third party company for help. If that is interesting for your company, we can provide the names of some third parties who have successfully written PRU Ethernet firmware in the past.

Ok, let's talk about PRU resources 

Hardware resources

A description of the hardware is in the AM64x Technical Reference Manual (TRM) > Processors > PRU_ICSSG chapter. There may be gaps in the documentation, so you would need to reach out if you had questions.

Software resources

The new AM64x PRU Academy is your getting started resource for PRU development. You would want to start with the PRU Getting Started Labs:
https://dev.ti.com/tirex/explore/node?isTheia=false&node=A__AZlFVyFPIrugfOX0nu3fMg__AM64-ACADEMY__WI1KRXP__LATEST

The OpenPRU repo is our new repository with sample PRU firmware:
https://github.com/TexasInstruments/open-pru

But the closest thing I have to "Getting Started" resources around writing Ethernet firmware is the SORTE_G project (i.e., Gigabit SORTE), currently located in the older PRU Software Support Package:
https://git.ti.com/cgit/pru-software-support-package/pru-software-support-package/tree/examples/am243x/SORTE_G

If you have questions about SORTE_G, I could point you towards the people who wrote that example.

AM64x == AM243x + A53 cores

We could also share the source code for PRU Ethernet switch firmware. That code is extremely complex, and we will not be able to support any questions about it.

How would I start?

SORTE_G is simpler than the switch firmware, so I would start by doing a deep dive into the SORTE_G project. If that is still something you are interested in working on, you could request the PRU Ethernet switch source code.

Regards,

Nick

The IRAD project I am working on has the need of multiple Ethernet connections, and due to the safety critical nature of the application (commercial aerospace) there are bus contention issues working against us - so we need to make use of PRU in addition to the CPSW Ethernet connections. We have a multicore solution, and applications running on separate core will use separate, dedicated Ethernet connections for their needs.

All that being said, it is worth you sending me the names of other companies who you have worked with to write custom Ethernet firmware. I will also get started with the Academy links you've sent. I am able to leverage an existing custom Ethernet code base from a previous program in-house, so am hoping that with some tailoring of the register accesses at a driver level I can make it work to test. I will reach out if I have any questions on the Academy instructions or setup.

Seth Appleman said:

it is worth you sending me the names of other companies who you have worked with to write custom Ethernet firmware.

You can reach out to Industrial Communication Protocol - CouthIT, they are well experienced in customizing PRU ethernet.

Nick, can you please also make available the "PRU Ethernet switch firmware" you mentioned above? I'm not afraid to dig into complex code, and am mostly interested in how the Ethernt registers are interacted with at that lowest level driver layer. Thanks.

Hello Seth,

Please have your local TI FAE reach out to me offline about getting access to the PRU Ethernet switch firmware.

Regards,

Nick

I'm not sure I have that contact information, so please let me know how I can find it or (if you have it) a name/resource listing I can refer to.Thanks

Hello Seth,

I am reaching out to our field team to figure out the right person. Is it ok if they contact you at your work email? If so I can grab it from your account and share it with them.

Regards,

Nick