02-18-2020 08:01 AM - edited 02-20-2020 01:57 AM
I am wondeirng about Ethernet connection on ZYNQ 7Z030. In which document I can find the conenction between ZYNQ7Z030 and Ethernet Port ?
02-18-2020 08:16 AM
Hi @peterjohn ,
Are you talking about a device part rather than the evaluation boards?
UG585 is the document for Zynq TRM and you can find GEM section there. Please take a look and see if that helps.
02-19-2020 01:10 AM - edited 02-20-2020 01:59 AM
The ZYNQ 7Z030 has two ARM A9 processors. It also has two hard Ethernet controllers. I am wondering what exactly is covered in ZYNQ as some development boards have Marvell chips while others have Realtek chips on board before the signal route to the Ethernet connector.
02-19-2020 01:53 AM
Thanks, now I understand that ZYNQ has MAC (GMII, RGMII, and SGMII interfaces). The Realtek and Marvell chips implement the PHY, the physical layer.
I am wondering about the popular development boards ZYNQ7Z030 that provide 1 Gbps. Is there any ZYNQ7Z030 development board with 1Gbps Ethernet on board whose schematic is also available ?
Is it really possible to get 1 Gbps ? I heard about 960 Mbps which is more practical. How this effect the system in term of speed. If one ARM processor is busy all the time with 1 Gbps Ethernet then the other ARM process will run the system sequentially which make the overall speed of the system slow.
02-19-2020 02:19 AM - edited 02-19-2020 02:20 AM
The question is forking into subquestions... posts are for free...
1 GbE is kind of the standard today, so I guess many boards will have it. Most dev boards have their schematic published as well. It doesn't have to be the 7z030, it would be the same with the 020, as the Ps is the same. It may be a bit different with the smallest ones 10 and 15 with only one core.
1 Gb/s is the data rate on the wires. But data is encoded 8b10b or 64b66b, so when you measure your data, it's less. Easy to reckon how much less. Then there are other factors: Ethernet requires a number of packets just to maintain the network, that also reduces practical bandwidth. I'd be happy with an effective 800 Mb/s.
About cores: whenever I used ethernet it was with Linux. Linux requires a minimum of two cores, apparently. so that scheme doesn't work. It might be possible with LwIp on bare metal or FreeRtos to have ethernet in one core and the other for other stuff, but it might not be the right approach: having separate applications on each processor will require inter-processor communications, that is not trivial. Your scenario of having one core busy with ethernet and the other with other stuff is equivalent to having a dual-core processor doing both tasks and busy 50% with ethernet and 50% with the other task. Most of Ethernet workload uses DMAs, not the core itself, you shouldn't worry (much) about that. When Ethernet slows down things is, in most cases, not for the traffic itself but for the data processing associated.
02-20-2020 01:56 AM
Thanks for your comment. It gives answer to some of my questions, but I am wondering about ARM cores and DMA in Ethernet. There is a dual core ARM Cortex A9 processor in 7020 and 7030.
In SDK we need to specify the ARM core for creating software application. The application could run on any of the two cores in 7020 and 7030. The application could be Hello Word or LwIp.
Is LwIp using DMA to offload the task to DMA ? If yes then the ARM core will not be busy all the time for Ethernet traffic, right ?