Introduction
The Enet CPSW fast startup example is dedicated to demonstrate the fast link up functionality of CPSW3G showing Strapped and forced mode configuration of PHY.
On AM263X, we can do ethernet based communication using CPSW as HW mechanism
- CPSW is a standard ethernet switch + port HW
- It uses ethernet driver underneath with LwIP TCP/IP networking stack
This example does:
- Demonstrates the strapped PHY functionality(Auto-Negotiation disabled).
- Target-side application running on a Cortex R5F core.
- The example enables both the ports of CPSW in MAC mode, creates a packet and sent it from port 1 to port 2.
- when the packet is received on port 2, the application prints out the profiling nodes and halts in a infinite loop.
Supported Combinations
| Parameter | Value |
| CPU + OS | r5fss0-0_nortos |
| Toolchain | ti-arm-clang |
| Boards | am263x-cc |
| Example folder | examples/networking/enet_cpsw_fast_startup |
Modifications needed before running the example:
EVM Board modification
- On AM263x-cc(PROC110E1), we need to disable Auto-negotiation in the PHY and force it to strapped mode with external starp resistors connected on PHY.
- To do that, modify below registers mentioned in below section for RGMII1 and RGMII2
- For other variants of AM263x, refer the schematics of board to modify the strap resistors for that specific EVM.
Modifications for CPSW RGMII1:
- Remove Strapping resistors from R270, R115, R278 and add the same to R101, R104, R284. All resistors are of same value.
Modifications for CPSW RGMII2:
- Remove Strapping resistors from R248, R240, R74 and add the same to R64, R60, R63. All resistors are of same value.
SW modifications
- We need to disable Enet Logs and recompiler the enet-cpsw library.
- To do so, remove the ENABLE_ENET_LOG define from mcu_plus_sdk/source/networking/enet/makefile.cpsw.am263x.r5f.ti-arm-clang makefile.
- Recompile the enet-cpsw library.
Media Dependent Interface(MDI configuration)
- With forced strapped mode, we don't have Auto-MDIX option in Phy, it can only be configured in manual MDI or MDIX mode, here in current configuration, we are setting both ports to manual MDIX mode.
- Ports that are connected by MDI-to-MDI and MDIX-to-MDIX connections must use crossover twisted-pair cabling.
- If straight cable is used, we need to put a switch in between the two ports.
- Refer the crossover cable wiring shceme given below:
Crossover cable wiring shceme
Tips to minimize link up time for Ethernet applications
- Auto-Negotiation on AM263X phy takes around 2-3 seconds, so to achieve quick link up, we cannot operate in Auto-Neg mode and have to use strapped and forced modes.
- Forced mode needs to be enabled on both sides of nodes.
- Typically Enet examples wait for 1 second after checking for link status.This is mainly considering auto-negotiation timing, but if forced and strapped mode, this delay can be significantly low, around 3ms(tested).
- HW strapped of PHY is needed to disble auto-negotiation when the phy is powered on.
Steps to Run the Example
Build the example
- When using CCS projects to build, import the CCS project for the required combination and build it using the CCS project menu (see Using SDK with CCS Projects).
- When using makefiles to build, note the required combination and build using make command (see Using SDK with Makefiles)
Run the example
- Attention
- If you need to reload and run again, a CPU power-cycle is MUST
- Launch a CCS debug session and run the example executable, see CCS Launch, Load and Run
- You will see logs in the UART terminal as shown in the next section.
Sample output for L2 CPSW Boot example
=====================================================
Fast Srtartup Profiling logs in Microseconds(us)
=====================================================
Application start time: 14
Enet-lld initialisation done time : 3024
Both ports linked up time: 8039
Time for First packet sent out from Port 1: 8057
Time for First packet received on Port 2: 8102
Application Terminating...
See Also
Ethernet And Networking
1.8.20