Teensy 4.1 Ethernet (With No Chip)

1

1unarz

New member
TL;DR, I accidentally purchased a Teensy without the Ethernet chip and want to know if there are any workarounds that don't involve buying a new board. Otherwise, I was wondering what the communication speed differences between Ethernet and Serial port are, and if I should even care about this.

I recently purchased a Teensy 4.1 from Digikey. I wasn't fully paying attention and there was no description that specified "no Ethernet" meant there was no Ethernet chip on the board. I had also previously purchased the Teensy 4.1 Ethernet Kit because I previously bought a different board with Ethernet functionality. After messing around a bit with different cables and using the NativeEthernet library I finally realized that I made a mistake. The fact that the board still has the open holes for soldering Ethernet makes me think that there is some workaround to the issue. In my setup, I plan to use a laptop as a computing unit that communicates with 3 Olimex ESP32 POE boards through Ethernet over a long distance to receive IMU data and transmit commands such as moving a motor. I also have 2 D435 cameras that I would like to ultimately make decisions about movement. The Teensy board primarily serves to receive instructions from the computer about how to move 12 servo motors and possibly handling some on-board calculations. As far as I know, the Teensy is completely overkill for this, but my main reasoning behind using Ethernet was to keep the communication protocol consistent and possibly allow for the POE boards to directly communicate with the Teensy for faster speeds. Any help is appreciated. Thanks.
 
Another quick note: I still have the previous board (I got the new one because it broke) and it appears to have the Ethernet chip on it. The pins are extremely small, so I doubt that I'll be able to transfer it over; however, if this is a viable option, I may consider it (assuming there is any point in pursuing this when I can just use USB).
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While adding the missing DP83825 chip could theoretically work, as a practical matter the odds of success are low even using the very best equipment. The 4 tiny pads on the 4 corners are particularly challenging to solder. If any sort of localized heating like a hot air rework is used, odds are strong you'll damage the rest of the board. The BGA chip is very close. Like all BGA chips, it doesn't like non-uniform heating.

Best to just save that no-ethernet Teensy 4.1 for another project.

But if you want to try anyway, Digikey sells that DP83825 part, so you could at least start with a fresh part if you place another order with Digikey. Picking up another Teensy 4.1 (or 2, so you have a space) could also relieve some of the stress... if you have at least 1 or 2 that work and the soldering effort ruins the no-ethernet board, at least it's easier to move on knowing you gave it a good try.

If you do try, I hope you'll share your experience here, either good or bad. I recall at least 1 other person talking about wanting to try this. As far as I know, nobody has actually attempted it (and shared their experience here). So the only answer I can give is pretty theoretical ... it ought to work if you can get the chip soldered correctly and add a few missing parts on the bottom side. But as far as I know, nobody has ever put that theory to the test.
 
If it were me I would use Serial. It has been reported here that the T4.1 Serial Port will work at 20MHz.
It may well be faster than Ethernet as there are no complicated protocols involved.
 
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OP notes distance and using POE for remote power supply? Ethernet might get 80 Mbps and include data integrity. Serial at higher speed would trigger a storm of frequent interrupts dealing with the small FIFO's on the 1062 UARTS.
 
Thanks for all of the input. At this point, a large amount of the processing is offloaded to a laptop because I need to visualize collected information. I'm pretty certain that most performance issues can be made up for with proper threading techniques in my calculations, so I don't want to get hanged up on the communication protocol for the Teensy (I have pretty tight time constraints).

After a bit of thought, as far as attaching the chip goes, I definitely don't have the proper equipment to solder it properly. If it turns out that I have issues with serial, I can access more Teensy boards fairly easily.

I'll be sure to post updates about what ultimately worked best for me.
 
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