Porting evkmimxrt1170_lwip_httpsrv_freertos_cm7 example to IMXRT117F - KSZ8081 no RX output

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Porting evkmimxrt1170_lwip_httpsrv_freertos_cm7 example to IMXRT117F - KSZ8081 no RX output

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transistor32
Contributor III

I have successfully used the evkmimxrt1170_lwip_httpsrv_freertos_cm7 example on the MIMXRT1170-EVK, configured to use the 100BASET port, where it behaves as expected; the web page can be loaded with the IP address and ping gets a response.

I would like to port this example to my own board to test the ethernet. My own board has an IMXRT117F and a duplicate of the circuit from the evaluation board connected to all the same pins including the KSZ8081RNB and the 7499211121A jack, so I'd expect the code from the evaluation board to work on my board with no changes required.

When run on my board, the serial console shows that the network has connected if the cable is plugged in (or not if it's not) but it is not possible to load a webpage and the LEDs on the jack do not blink.

On connection, some packets are detected on the network by Wireshark and the MAC address of the board is detected by arpwatch.

transistor32_0-1700065710922.png

When probing the signals on the board, the TXD0, TXD1 and TXEN pins have the expected waveforms on them. The RXD0, RXD1 and RXEN pins of the KSZ8081 have no signals on them on my board, whereas they do on the evaluation board. The RD- and RD+ pins from the jack have signals on them that look correct and the waveforms on these pins look the same on my board and on the dev board.

It looks like the KSZ8081RNB is not outputting the received data on my board whereas it is on the evaluation board. Is there any configuration issue or difference between the IMXRT1176 (on the dev board) and IMXRT117F (on my board) that could cause this? I note that the latter doesn't have TSN on the 1Gbit port whereas the former does, and although I'm using the 100Mbps port only, I wonder if there's other differences between the IMXRT1176 and IMXRT117F? Or could it only be a hardware design issue?

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transistor32
Contributor III

The problem was that the pull-up resistor on pin 21 is meant to be 1k as shown on the evaluation kit schematic, but the resistor actually fitted to my PCB was 10k. I didn't think to check this one originally because it looks like a non-critical value, but it is in fact very critical. The example project works as expected with this resistor corrected.

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transistor32
Contributor III

The problem was that the pull-up resistor on pin 21 is meant to be 1k as shown on the evaluation kit schematic, but the resistor actually fitted to my PCB was 10k. I didn't think to check this one originally because it looks like a non-critical value, but it is in fact very critical. The example project works as expected with this resistor corrected.

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jingpan
NXP TechSupport
NXP TechSupport

Hi @transistor32 ,

RT117F is base on RT1173. Besides TSN, other features are same.

 

Regards,

Jing

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