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gusmanb / logicanalyzer

24 channel, 100Msps logic analyzer hardware and software
GNU General Public License v3.0
2.33k stars 259 forks source link

Pico 2 and the 2350, floating pin issue #142

Closed Multithought closed 1 month ago

Multithought commented 1 month ago

Hello,

I came across your project on a YouTube channel. But I saw you were porting to pico2 and stopped due to the latch-up issue

Re-read the errata. The issue doesn’t affect your 24 input channels. It’s not an issue. In your device the level shifters are driving the inputs of the RP active low or high. The issue only occurs when the pins are weakly driven low or floating.. open collector etc. with the active, driven outputs of the level shifters, you will not see the latch-up issue. To be extra sure if you want just turn on the pull up internal to the 2350.

I have already made and delivered to market, a product based on the RP2350A2 (30,000 of them) It’s not a problem in this, and indeed most situations.

-Matt

gusmanb commented 1 month ago

Hi.

I've been involved in the case since the beginning in the Raspberry forums and Github. It does affect, I already diagnosed it and for now it is stopped.

The device can be used without the shifters, the most basic form of the analyzer is the pico barebones, if anyone uses it like that the pico will mess up the analyzed signals leading to unexpected results.

There are evidences on the E9 thread on Github that a signal connected to an RP2350's GPIO is distorted and that's something that a logic analyzer cannot afford.

Cheers.