 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Microcontroller and PC projects : PGA2350 Scematic available
| Author | Message | ||||
Mixtel90 Guru  Joined: 05/10/2019 Location: United KingdomPosts: 6779 |
From Pimorini It was delayed for a while. No surprises really. IOVDD is connected to 3V3 so, in theory anyway, at least some IO pins are 5V tolerant. Input voltage high: 2V to IOVDD+0.3V (2-3.6V) Input voltage low: -0.3V to 0.8V Input voltage high (FT): 2V to 5.5V IF THE SUPPLY TO THE CHIP IS ON. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
||||
stanleyella Guru Joined: 25/06/2022 Location: United KingdomPosts: 2120 |
no disrespect just this is not back to 80's basic. isn't mmbasic pico getting more stuff that... hands up who has no problem with the new terminology and pico "stuff"? maybe a newbie would be put off and think it too complicated. don't get me wrong , development is the future... just I lost the thread with dvi,hdmi :) |
||||
| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6779 |
It's just a way of getting more colours really, Stan. The new chip has a special system that lets it generate a more modern video standard than VGA. That's a big advantage, especially as some modern monitors don't have a VGA input now. A lot of the 80's computers had several video modes. This isn't unusual really. This thread is technical - it's of interest to the "how it works" people rather than the users, who have no use for a schematic (usually!). Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
||||
| zeitfest Guru Joined: 31/07/2019 Location: AustraliaPosts: 482 |
Looks like pin 47 is connected for PSRAM CS... also SPI1. Wondering if that will interfere with most spi1 port use  Edited 2024-09-05 12:58 by zeitfest |
||||
| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6779 |
Pin 47 is connected via a "solder blob" link. If you cut it you can use pin 47 as you like, but you will lose access to PSRAM under MMBasic as it is used for the CS pin. There are alternatives which matherp could have used but they all clash with something either useful or already allocated on a Pico 2, which would be a lost pin as the Pico 2 has no PSRAM. There are many alternative pins for SP1. :) Edited 2024-09-05 17:02 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
||||
| zeitfest Guru Joined: 31/07/2019 Location: AustraliaPosts: 482 |
Is that link, the axe-shaped pads on the flip side ? |
||||
| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6779 |
Yes. Just under the M of PIMORINI. I'd forgotten. You can use OPTION PSRAM PIN n to set the enable pin to a different one. n can be one of 0, 8, 19 or 47. We usually use GP8 for the console and GP19 for the HSTX so that usually only gives a choice of GP0 or GP47. . Edited 2024-09-06 00:32 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
||||
| zeitfest Guru Joined: 31/07/2019 Location: AustraliaPosts: 482 |
Thanks TBH I'm not using basic, (C/C++/Arduino mainly) but the pins info is the same. The errata9 says the have stopped shipment while they consider the latch problem link so I might delay a bit |
||||
| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6779 |
So far RPi say that there is nothing wrong with the chip that can't be catered for with proper circuit design. Yes, it affects some back compatibility with the RP2040, but that's all. I wouldn't hold your breath waiting for a corrected chip. Even if they do one they are highly unlikely to announce it anyway, it will simply appear with a different revision number and the Datasheet will be updated shortly after. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
||||
| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3800 |
Please have a look at the comments about ADC in this ... they seem quite serious but am I misunderstanding? John |
||||
| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6779 |
Well, it depends on how you look at the problem. Active low inputs with internal pull up resistors are working. This is how the vast majority of commercial applications work and that is Raspberry Pi's potentially biggest market for these chips. Active high inputs are insensitive and require far more drive than MOSFET inputs usually do. They are sourcing enough current to require external pull down resistors. This mode is rarely used commercially as all signals tend to share a common ground, not a common supply. A similar, and possibly related, problem is with the ADC inputs. They require a lower input impedance drive than usual. Once again though, commercial applications will usually be giving it inputs from op amp buffers as they will be doing signal conversion. It isn't an issue. None of these is a problem if you say that the the RP2350 is a new chip that is only partially compatible with the RP2040. None of them prevents the chip from working, although they might prevent it from working in some RP2040 circuits. Raspberry Pi have little incentive to fix these problems for the sake of fixing partial compatibility issues with some RP2040 circuits. It wouldn't make commercial sense. All they need to do is document the issues and designers will work round them for new designs. If there is any "fault" with the RP2nnn designs it's that there are no open drain outputs. These are used fairly extensively in commercial settings and IMHO it's something they should have looked at. Ok, you can simulate them for 3V3 or just add an external MOSFET. I suppose it keeps voltages that could be higher than 5V off the chip though. . Edited 2024-09-06 21:39 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
||||
| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3800 |
Mick - thanks. John |
||||
 Print this page |
