# Trouble connecting Arduino Portenta H7 to Gigablox Nano

**URL:** <https://forum.botblox.org/t/trouble-connecting-arduino-portenta-h7-to-gigablox-nano/201>\
**Category:** BotBlox Hardware\
**Tags:** gigablox-nano\
**Created:** [April 16, 2024, 5:15pm UTC](https://forum.botblox.org/t/trouble-connecting-arduino-portenta-h7-to-gigablox-nano/201 "2024-04-16T17:15:40Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Agolfer](https://avatars.discourse-cdn.com/v4/letter/a/8dc957/32.png) [@Agolfer](https://forum.botblox.org/u/Agolfer)\
**Post date:** [April 16, 2024, 5:15pm UTC](https://forum.botblox.org/t/trouble-connecting-arduino-portenta-h7-to-gigablox-nano/201/1 "2024-04-16T17:15:40Z")

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- I am not able to connect to my Ardhuno Portenta H7 to Port 1 of the Nano switch on a new PCB design. With that design, the green power LED does light and I have a Laptop connected via R&45 with magnetics to Port 0 (all at 100mb) and that connects fine - the port 0 LEW does show green even though I have only wired Ports A/B). I have checked connectivity and that shows good between the Arduino pins and the Nano pins. See diagram below. Any thoughts appreciated.

![image](https://canada1.discourse-cdn.com/flex027/uploads/botblox1/original/1X/778064708e9da7804a4738629e01dcf690fb2542.png)

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**Author:** ![josh\_elijah](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.botblox.org/josh_elijah/32/568_2.png) [@josh\_elijah](https://forum.botblox.org/u/josh_elijah)\
**Post date:** [April 17, 2024, 3:48am UTC](https://forum.botblox.org/t/trouble-connecting-arduino-portenta-h7-to-gigablox-nano/201/2 "2024-04-17T03:48:51Z")

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Pinout looks good.

The Portenta H7 uses the LAN8742AI-CZ-TR as the ethernet PHY.

GigaBlox Nano uses voltage mode PHYs.

It’s not stated from the datasheet, but from the application diagrams, it looks like LAN8742AI-CZ-TR uses a current mode PHY. This requires transformers with the center tap connected to the positive rail to work. Transformerless ethernet only works with voltage mode phys.

Read more about that in the link below.

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This is probably your issue.