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I got almost all of my wishes granted with RP2350

(dmitry.gr)
700 points elipsitz | 10 comments | 08 Aug 24 13:03 UTC | HN request time: 0s | 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

replies(5): >>41192318 #>>41192351 #>>41193287 #>>41194312 #>>41194963 #
1. synergy20 ◴[08 Aug 24 15:06 UTC] No.41192318[source]▶
Wow, can't wait. Love the 5V GPIO and security features.
replies(1): >>41192934 #
2. Daneel_ ◴[08 Aug 24 16:00 UTC] No.41192934[source]▶
5V GPIO is a huge deal for me - this immediately opens up a huge range of integrations without having to worry about line level conversion.

I can’t wait to use this!

replies(2): >>41194769 #>>41195192 #
3. azinman2 ◴[08 Aug 24 18:36 UTC] No.41194769[source]▶
Does tolerant mean ok to do? Or it just won’t fry your chip but you should actually run at 3.3?
replies(2): >>41195039 #>>41195775 #
4. tredre3 ◴[08 Aug 24 19:04 UTC] No.41195039{3}[source]▶
It usually means it's clamped so it might result in a small amount of wasted energy/heat but no damage.

So yes it means it's okay but if you can you should go for 3.3.

5. HeyLaughingBoy ◴[08 Aug 24 19:18 UTC] No.41195192[source]▶
Be careful with assumptions though. Being 5V tolerant doesn't mean that your 3V output can sufficiently drive an input that expects 0-5V levels correctly.

I ran into this problem using an ESP32 to drive a Broadcom 5V LED dot-matrix display. On paper everything looked fine; in reality it was unreliable until I inserted an LS245 between the ESP and the display.

replies(2): >>41196928 #>>41197045 #
6. murderfs ◴[08 Aug 24 20:20 UTC] No.41195775{3}[source]▶
5V tolerant means that it'll accept 5V input (and correctly interpret it as high), but output will still be 3.3V.
7. lloydatkinson ◴[08 Aug 24 22:14 UTC] No.41196928{3}[source]▶
> LS245

Do you think that would be a good IC to drive these with a RP2040? https://www.analog.com/en/products/max7219.html

replies(1): >>41196971 #
8. HeyLaughingBoy ◴[08 Aug 24 22:20 UTC] No.41196971{4}[source]▶
A better question might be why anyone is using a MAX7219 on a new design in 2024. There are so many other choices for displays than a 20 year-old IC from a company that's gone through two changes of ownership since.

Anyway, a 74LS245 isn't a level shifter, it's an octal buffer. It just happened to be the right choice for my needs. In your application, I'd suggest an actual level shifter. You can find level shift breakout boards at Sparkfun and Adafruit.

9. irdc ◴[08 Aug 24 22:28 UTC] No.41197045{3}[source]▶
> Being 5V tolerant doesn't mean that your 3V output can sufficiently drive an input that expects 0-5V levels correctly.

It's fine for TTL (like your 74LS245 is), which registers voltages as low as 2V as a logical 1. Being able to directly interface with TTL eases up so many retrocomputing applications.

replies(1): >>41198408 #
10. HeyLaughingBoy ◴[09 Aug 24 02:44 UTC] No.41198408{4}[source]▶
Which was... exactly the reason I chose it?