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Forum Index : Microcontroller and PC projects : PicoMite RP2350B DIL Development board, 16Mb flash + 8 MB PSRAM
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| circuit Senior Member  Joined: 10/01/2016 Location: United KingdomPosts: 268 |
Peter, thank you for that information. I have read the reference that you gave me and now I see that GP29,31,32, and 34 are 5V tolerant as you advise, but this applies only to the 80pin chip and that is what I had missed. Regretfully, I cannot revise my diagram today; I appear to have caught Covid - two very bright red lines on the test pot! With my temperature rising by the hour, I have no competence to do much at the moment. Five days of hell starts now...if it all runs as expected. The irony is that the UK is starting the Spring booster vaccination on Tuesday. |
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Mixtel90 Guru  Joined: 05/10/2019 Location: United KingdomPosts: 7499 |
It's the ADC pins (GP40-GP47) that aren't 5V tolerant. Yep, it's a change from the A version. :) I hope you get over the Covid quickly. Get well soon! . Edited 2025-03-26 22:45 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3309 |
After soldering 2 psrams on and flashing, I get this (joy): option list PicoMite MMBasic RP2350B Edition V6.00.02RC15 OPTION FLASH SIZE 16777216 OPTION PICO OFF OPTION CPUSPEED (KHz) 150000 OPTION PSRAM PIN GP0 > memory Program: 0K ( 0%) Program (0 lines) 288K (100%) Free Saved Variables: 16K (100%) Free RAM: 0K ( 0%) 0 Variables 0K ( 0%) General 6480K (100%) Free > I soldered on a 3rd psram--what I looks to me like the cleanest job--and after flashing, it always again presents the D: drive, ready for flashing again (which I can do). Any ideas about cause and possible remedy? PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10066 |
PSRAM chips wrong way round? |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3309 |
No, the little dot on the chip is next to the white dot on the PCB. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10066 |
Fake PSRAM? You should have paid at least $1 each if not more  |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3309 |
I bought 5 at the same time. First two worked. Paid $.95USD each. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2927 |
Also possible to damage PSRAM chip if too much heat applied while soldering; not to mention ‘static discharge! Avoid the cheap PS chips if you don’t want any headaches (otherwise it is a gamble if they work) |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3309 |
It behaves as if the Boot button is stuck down, though I can't tell that it is. I didn't think to flash it before soldering in the PSRAM, so don't know if the problem was pre-existing. I will flash my two remaining modules before trying to solder on the PSRAM. There's little lost if I have to desolder the PSRAM on the failing PCB (if that fixes the problem). Is there a failure mode for the PSRAM which might be likely to cause this behavior? (I have no particular planned use for these 64-pin jobbies anyway.) PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2927 |
Two things. 1: are you definitely using the correct firmware? On one occasion I was stupidly using the wrong firmware and I had exactly this situation where it kept presenting the D: drive (although I may have been loading a newer version on top of an older version). On loading the correct one, all was good. 2: Something I noticed when I had a lot of the DIL modules in front of me is as follows. I programmed the first few units with firmware before soldering PSRAM, set the options manually but NOT the PSRAM PIN, then soldered the PSRAM to check unit still worked, then set option for PSRAM pin. Doing this, all was good (it was just me being curious as to checking all worked at each step). However, I then took a unit (before PSRAM chip soldered) but set the option for PSRAM pin. On boot up, kept seeing the d: drive. So thinking that soldering in PSRAM chip would solve this, I went ahead and soldered it but unit would not fire up (but d: drive showing). The only way I found around it was to load a wrong version of firmware, then reload correct version. I had tried option reset along the way but some options seemed ‘persistent’. I have not repeated this sequence of setting option then soldering since this; I just took it as a lesson to solder chip first before setting PSRAM pin option. Sorry for the long post, but there is some similarities in both the above scenario to what you’re seeing. |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10066 |
This is an "unfortunate" feature which I will correct. In the next version setting the PSRAM PIN will be ignored if the PSRAM is not present |
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| circuit Senior Member Joined: 10/01/2016 Location: United KingdomPosts: 268 |
I think that I welcome this because I do not need PSRAM. Therefore, if I remove R23 and hotwire over to pad 1 where the PSRAM chip is supposed to be, I then regain GP0 for all normal purposes? I would really like to mount up an SSD1963 from this side of the board, 16 bit starting at GP0. Edited 2025-04-17 19:30 by circuit |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10066 |
The issue is irrelevant if you don't allocate a PSRAM pin when there is no PSRAM present or allocate the wrong pin. |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3309 |
I will need that version when it becomes available, since I flashed one of my two untouched units and set the OPTION PSRAM PIN. Haven't yet recovered from that. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10066 |
Just load clear_flash or a different firmware |
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