topic Re: Using KSZ8081RNA with RT1050 in i.MX RT Crossover MCUs

Solved: Using KSZ8081RNA with RT1050

giuseppescarpi — Thu, 29 Nov 2018 16:37:02 GMT

Hi fellow engineers,

we are developing a board with RT1050 that uses the RNA physical chip instead than RNB version as in the EVKB.

So far we have had no success in making our board work. I hope someone has experience with this.

This is the scenario.

1) we modified the connections between the PHY and the MCU as shown in the image.

2) we are using the lwip_ping demo firmware that comes in MCUXpresso

3) the only change we did is setting BOARD_ENET0_PHY_ADDRESS to zero instead than 2. By doing so, the PHY recognizes a connection and negotiates a 100 Mbps link. The MCU correctly reads the status of the PHY.

We get traffic on the RX[0..1] lines, but TX_EN is low, and there is no traffic on TX[0..1].

We connected ETH.RST and ETH.INT to GPIOs. When the board starts, there is a cycle reset.

REFCLOCK gets a 25 MHz from the MCU (pin B13 configured as REF_CLK)

CRS_DV is connected to pin G2, configured as RX_EN like in the EVK board.

Any hints?

:-)

Re: Using KSZ8081RNA with RT1050

art — Fri, 30 Nov 2018 10:27:39 GMT

To make me able to accurately study the case, please provide some more information.

What's on the other side of the Ethernet link? You said that there is some activity oh the RX[1:0] signals, so, RT1050 should receive something. Does it? Does RT1050 output any log on the serial console?

Also, please provide the PHY data sheet and the complete schematic of your hardware.

Have a great day,
Artur

Re: Using KSZ8081RNA with RT1050

giuseppescarpi — Fri, 30 Nov 2018 13:27:24 GMT

Hi Artur, thank you for your answer.

It seems that the RT1050 does not receive anything. The firmware works in the EVK-B, but when ported to our board (changing some Ethernet pins assignment and the GPIOs for RST and INT), it does not.

Of course I have no problems to provide you the datasheet. For the schematic, I cannot publish it on the forum. If you want I can either send it to an NXP email address (we already have an NDA in place with NXP), or contact your FAE in Italy (Mr. Ferrari).

Giuseppe

http://ww1.microchip.com/downloads/en/DeviceDoc/00002199A.pdf

Re: Using KSZ8081RNA with RT1050

giuseppescarpi — Thu, 06 Dec 2018 16:06:19 GMT

In the end I discovered the problem.

The hardware is perfectly OK, and you can use versione RNA of the physical with zero changes.

The problem was a settings in the reference clock pin. You have to enable the "Software Input On" flag in the pin configuration.

By default, this is set to Disabled. SDK projects override the value to Enabled, but when you relocate the signal to a different pin (this was our case) you lose the override.

So, caveat emptor!

Once the flag is set, the lwip examples work with no problems.

Giuseppe