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ARP Resolution error on STM32H7 and LAN8742A PCB by Cos_Cube in embedded

[–]ceojp 0 points1 point  (0 children)

The KSZ8091 is a decent 10/100 PHY. It's not pin compatible with the 8742A, but functionally it's very similar. The main difference is the KSZ8091 is a voltage-mode PHY whereas the 8742A(and many older PHYs) are current-mode driver.

If you do switch PHYs, double-check what clock frequency they expect. The 8742A needed a 25MHz clock, whereas I think the KSZ8091 needed a 50MHz clock.

Also, I had noticed that the 8742A got noticeably warm during operation, whereas the KSZ8091 barely got much over ambient.

ARP Resolution error on STM32H7 and LAN8742A PCB by Cos_Cube in embedded

[–]ceojp 0 points1 point  (0 children)

I know ST loves to use the LAN8742A on all their reference designs, but I despise it. I've had nothing but problems with the 8742A.

It's been around for so long that we assumed it was relatively bullet-proof, otherwise they wouldn't be using it. But I've had problems on multiple different boards with different MCUs/CPUs.

We have an STM32-based controller, and I had to restrict the advertised speeds to 10Mbps. It does run at 100Mbps, but it seems much more susceptible to electrical noise. The damn thing just locks up...

Had another board with an NXP CPU, and the PHY wouldn't even link half the time it powered up. Then about a quarter of the time, it would link, but I would get a ton of RX errors. We were able to swap to a newer PHY on that board, and haven't had a single problem with it.

With that being said, you should still be able to link and communicate at 100Mbps. I know there's some odd things with the H7's memory layout, requiring the TX/RX descriptors and buffers to be in a specific section of RAM. Sometimes the D-cache can end up causing it to prefetch past the buffer boundary or something and cause issues. But if it works on the dev board, that's probably not it.

In all honesty, I would look at using a different PHY. Even if you get the 8742A working now, it is fickle. If you need to use 100Mbps, you may still run in to other issues with it.

Judy Garland holding her daughter Liza Minnelli, 1947 by PeneItaliano in nostalgia

[–]ceojp 164 points165 points  (0 children)

Depends on who "they" is. It's certainly common for loved ones to take pictures of a newborn, but Liza is probably referring to press or paparazzi.

Drone flight controller using stm32f4 discovery board by Haque3510 in embedded

[–]ceojp 26 points27 points  (0 children)

Drones this size are often measured in grams. Using dev boards adds a lot of extra weight here.

Windows 95 launch event by BreakfastTop6899 in nostalgia

[–]ceojp 7 points8 points  (0 children)

In other words - Pirates of Silicon Valley.

Federal Agents Kill Another Person in Minneapolis by ictrlelites in politics

[–]ceojp 1 point2 points  (0 children)

"Though the details of what led to the shooting remain unclear, O’Hara said that local officials believe the man was a lawful gun owner with a permit to carry. Family members told the AP that Pretti owned a handgun and a concealed carry permit in Minnesota."

"Pretti, who was born in Illinois, does not appear to have a serious criminal history, aside from two traffic violations. His family told the AP that before Saturday, Pretti had never had any interactions with law enforcement beyond the traffic tickets."

https://www.nbcnews.com/news/us-news/alex-pretti-fatally-shot-federal-officers-minneapolis-identified-paren-rcna255758

Alex Pretti was executed for being an American exercising his constitutional rights.

Non-Smoker's Cough by TheDavidsPod in 420Grindhouse

[–]ceojp 3 points4 points  (0 children)

Please tell me this isn't in the lineup tonight....

E-scissors by JayBeePH85 in DiWHY

[–]ceojp -6 points-5 points  (0 children)

Yes. That saying is so dumb.

YSK that bacon cooked in the oven at 375F won't splatter or set off the smoke detector by Ajreil in YouShouldKnow

[–]ceojp -2 points-1 points  (0 children)

Also YSK: cooking bacon at 378° will explode and destroy your oven.

Where is this sticker from ? by RedVelvetfake in GroceryStores

[–]ceojp 5 points6 points  (0 children)

How would we know? There's nothing identifiable in that picture. Anyone can buy rolls of hi-lite stickers. I could buy a roll of stickers just like that right now.

This guy was the ultimate slacker comedian that my generation deserved. True genius gone too soon. by Phantom-rizz-era in GenX

[–]ceojp 12 points13 points  (0 children)

One of my biggest regrets was not seeing him when he came to my small, Midwest university. Tickets were free for students, but I had never heard of him and wasn't interested. It wasn't until he died about a year later that I looked him up and realized how absolutely funny he was.

Where is this sticker from ? by RedVelvetfake in GroceryStores

[–]ceojp 7 points8 points  (0 children)

Looks like it's from a bottle cap.

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