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NNTP-Posting-Date: Mon, 19 Aug 2024 14:38:23 +0000
From: john larkin <jlarkin_highland_tech>
Newsgroups: comp.sys.raspberry-pi,sci.electronics.design
Subject: Re: New Pico2
Date: Mon, 19 Aug 2024 07:38:23 -0700
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On Mon, 19 Aug 2024 22:04:19 +1000, Chris Jones
<lugnut808@spam.yahoo.com> wrote:

>On 13/08/2024 12:43 pm, John Larkin wrote:
>> On Mon, 12 Aug 2024 18:41:59 +0200, Lasse Langwadt <llc@fonz.dk>
>> wrote:
>> 
>>> On 8/11/24 23:07, John Larkin wrote:
>>>> On Sun, 11 Aug 2024 14:04:36 -0700, John Larkin
>>>> <jjlarkin@highlandtechnology.com> wrote:
>>>>
>>>>> On Sun, 11 Aug 2024 21:45:42 +0100, Andy Burns <usenet@andyburns.uk>
>>>>> wrote:
>>>>>
>>>>>> Surprised nobody has mentioned the Pico2 boards (based on RP2350A or
>>>>>> RP2350B chips, instead of RP2040).
>>>>>>
>>>>>> 2x ARM cores plus 2x RISC-V cores (perm any 2 from 4)
>>>>>> 150 MHz with FPU instead of 133MHz without
>>>>>> lower power consumption
>>>>>> more I/O pins (B model only?)
>>>>>>
>>>>>> I really ought to buy a couple for tinkering ...
>>>>>>
>>>>>> official boards not available yet, but 3rd party boards are, e.g.
>>>>>>
>>>>>> <https://shop.pimoroni.com/products/tiny-2350?variant=42092638699603>
>>>>>> <https://shop.pimoroni.com/products/pga2350?variant=42092629229651>
>>>>>
>>>>> As of now, Digikey shows no stock on the Pico2 and doesn't recognize
>>>>> the RP2350 chip as a product. Ditto Mouser.
>>>>>
>>>>> The fast floats look great. I wonder how fast they are.
>>>>
>>>> The RP2350 data sheet is 1347 pages!
>>>>
>>>
>>> read the part on how the build in buck converter needs a custom inductor
>>> with polarity marking to work, and tell there is something seriously
>>> wrong with it
>> 
>> The polarized inducor is strange. I'd expect that a small shielded
>> inductor would work fine. It is interesting to have a switching
>> regulator on a CPU chip... near a 12-bit ADC!
>
>I don't think they know much about how to do ADCs yet.
>
>Have a look at the performance of the RP2040 ADC - it is awful!
>
>http://pico-adc.markomo.me/
>
>I hope the new one is better.
>
>

It's tough to put a good 12-bit ADC on a 70 cent dual-core CPU chip.
The silicon process, the thermals, the ground loop and noise
environment, are all wrong.

The 2040 ADC has chunks of missing codes. It's probably usable as a
7-bit, 1% ADC. Some lowpass filtering, with some dithering, would
improve it but if you want precision, buy a separate ADC.

We use the ADCs in FPGAs and some other ARM processors, for crude
things like checking power supplies. Not for sellable instrumentation.