Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [lan8720]

7 questions
12
votes
3 answers

STM32F407 + LAN8720A + lwIP + FreeRTOS = No received Ethernet frames

I'm trying to bring up a PCB that uses an STM32F407 and LAN8720A Ethernet PHY, and I can't seem to receive any Ethernet frames — even though I have no problem transmitting frames. Hardware setup I have a 25 MHz crystal on the STM32F4, driving a 25…
Jay Carlson
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1
vote
1 answer

LAN8720 50Mhz clock: 33R termination/adaptation resistors

I'm trying to understand the function of these three 33R ohms resistors. The full schematic is here: Schematic I can understand the objective of R14 and R12: Split the clock and adapting it, but what is the function of R11? Is it another…
Kotik_o
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1
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1 answer

Crystal Oscillator for STM32F407 with LAN8720

I'm planning to build a custom board with STM32F407 chip for a system where I also need Ethernet connectivity. I'm planning to connect this board to a LAN8720 with breakout board from Smart Electronics to have Ethernet connectivity (two independent…
Leandro Loureiro
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0
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1 answer

STM32F407 + LAN8720 status LED keeps blinking fast, error?

I made a custom board around STM32F407 MCU that is connected with a PHY Board with a LAN8720 IC via RMII. I also have connected an 2.42' OLED Display based on SSD1309. I notice when I turn on the OLED display, the status/activity LED starts blinking…
Leandro Loureiro
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0
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1 answer

Problem with ferrite bead - reduces power supply voltage

I built my own board with a LAN8720 chip but I can't get it to work. I found out that the ferrite bead I used only outputs ~1.4V from 3.3V input, which is way too low. I used some guidelines and other boards as examples for the layout. The first one…
Daniel Do
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0
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1 answer

Identification of Pin1 on LAN8720A 24SQFN package

can anybody help me identify which is pin 1 please? - which corner and side is pin 1? I find the data sheet and the actual picture confusing between the Datasheet and the device
Daveo
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2 answers

Inverting REFCLOCK of Ethernet PHY

A few years ago I had to design a board that uses the NXP LPC1769 MCU and had Ethernet connectivity. I was in need of a PHY chip and the LAN8720 was choosen. During design however, I noticed that NXP in their development boards use an inverting…
Fotis Panagiotopoulos
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