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I got almost all of my wishes granted with RP2350

(dmitry.gr)
700 points elipsitz | 12 comments | 08 Aug 24 13:03 UTC | HN request time: 0.765s | source | bottom
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blackkat ◴[08 Aug 24 15:02 UTC] No.41192280[source]▶
Some specs here: https://www.digikey.ca/en/product-highlight/r/raspberry-pi/r...

Based on the RP2350, designed by Raspberry Pi in the United Kingdom

Dual Arm M33s at 150 MHz with FPU

520 KiB of SRAM

Robust security features (signed boot, OTP, SHA-256, TRNG, glitch detectors and Arm TrustZone for Cortex®-M)

Optional, dual RISC-V Hazard3 CPUs at 150 MHz

Low-power operation

PIO v2 with 3 × programmable I/O co-processors (12 × programmable I/O state machines) for custom peripheral support

Support for PSRAM, faster off-chip XIP QSPI Flash interface

4 MB on-board QSPI Flash storage

5 V tolerant GPIOs

Open source C/C++ SDK, MicroPython support

Software-compatible with Pico 1/RP2040

Drag-and-drop programming using mass storage over USB

Castellated module allows soldering directly to carrier boards

Footprint- and pin-compatible with Pico 1 (21 mm × 51 mm form factor)

26 multifunction GPIO pins, including three analog inputs

Operating temperature: -20°C to +85°C

Supported input voltage: 1.8 VDC to 5.5 VDC

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1. jayyhu ◴[08 Aug 24 18:57 UTC] No.41194963[source]▶
Edit: See comment below; The RP2350 can be powered by a 5V supply.
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2. giantg2 ◴[08 Aug 24 19:18 UTC] No.41195190[source]▶
I'd rather have it run on the lower voltage - generally easier to step down than buck up. Either way, the modules are pretty cheap, small, and easy to find.
3. skykooler ◴[08 Aug 24 19:29 UTC] No.41195265[source]▶
How much tolerance does that have - can it run directly off a 3.7v lithium ion battery?
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4. Findecanor ◴[08 Aug 24 20:02 UTC] No.41195602[source]▶
To clarify: You can connect a 5V power source by connecting it to the VSYS pin which leads into the on-board voltage regulator.

But the µC itself runs on 3.3V and is not totally 5V-capable. You'd need level converters to interface with 5V.

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5. ◴[08 Aug 24 20:06 UTC] No.41195635[source]▶
6. jayyhu ◴[08 Aug 24 20:28 UTC] No.41195864[source]▶
You're right, after re-reading the Power section on the datasheet it seems connecting 5V to the VREG_VIN should suffice to power the digital domains, but if you want to use the ADC, you still need a external 3.3V source.
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7. jayyhu ◴[08 Aug 24 20:45 UTC] No.41196060[source]▶
Yep, they explicitly call out that the onboard voltage regulator can work with a single lithium ion cell.
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8. dvdkon ◴[08 Aug 24 21:02 UTC] No.41196227{3}[source]▶
The regulator can take that, but as far as I can see it's only for DVDD, the core voltage of 1.1 V. You also need at least IOVDD, which should be between 1.8 V and 3.3 V. So you'll need to supply some lower voltage externally anyway.

I suppose the main draw of the regulator is that the DVDD rail will consume the most power. 1.1 V is also much more exotic than 3.3 V.

9. dvdkon ◴[08 Aug 24 21:04 UTC] No.41196253{3}[source]▶
Maybe not even that:

> A separate, nominally 3.3 V, low noise supply (VREG_AVDD) is required for the regulator’s analogue control circuits.

It seems it would be painful trying to run this without 3.3 V.

10. snvzz ◴[09 Aug 24 00:40 UTC] No.41197814[source]▶
>You'd need level converters to interface with 5V.

Part of the GPIOs are CMOS are 5v-tolerant, and TTL considers 2v HIGH, thus it is possible to interface some 5v hardware directly.

11. snvzz ◴[09 Aug 24 03:31 UTC] No.41198559{3}[source]▶
See section on physical pin gpio electrical tolerances.

The TL;DR is that 3.3v must be fed into IOVDD for 5.5v tolerance to work.

12. crote ◴[09 Aug 24 07:42 UTC] No.41199626{3}[source]▶
It's quite a bit more complicated.

The chip needs a) 1.1V to power the cores, b) 1.8V-3.3V to power IO, and c) 3.3V to properly operate USB and ADC.

The chip has one onboard voltage regulator, which can operate from 2.7V-5.5V. Usually it'll be used to output 1.1V for the cores, but it can be used to output anything from 0.55V to 3.3V. The regulator requires a 3.3V reference input to operate properly.

So yeah, you could feed the regulator with 4-5V, but you're still going to need an external 5V->3.3V converter to make the chip actually operate...