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Forum Index : Microcontroller and PC projects : Option Cpuspeed and core voltage....
| Author | Message | ||||
| DigitalDreams Newbie  Joined: 03/05/2025 Location: United KingdomPosts: 17 |
When changing clock speed with option cpuspeed I guess this also increases core voltage ?. How can we see what that voltage is and maybe set it ourselves from MMBasic ? |
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Mixtel90 Guru  Joined: 05/10/2019 Location: United KingdomPosts: 7800 |
Even if it's possible (and I doubt if it is), I don't think it would be a great idea to allow a BASIC program to change the core voltage. :) You can't change the CPU speed from within a program anyway as it requires (or at least used to) a CPU restart. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| DigitalDreams Newbie Joined: 03/05/2025 Location: United KingdomPosts: 17 |
From the prompt then, and maybe determine set voltage by peeking an address ? |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10170 |
Please use MMbasic as-is and stop trying to change it. The firmware sets an appropriate voltage for each cpuspeed. However, the internal switching regulator is limited in its stability and current generating capability. My designs use an external linear source for DVDD and overclock reliably. The Pico2 is pretty good as well. Pimoroni boards are notoriously poor at overclocking and this is not just a voltage issue. Specifically the presence of the PSRAM chip seems to reduce overclockability. There will be no change to allow setting the voltage from MMBasic, it wouldn't fix the issue with Pimoroni boards in any case. |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7800 |
I think he wanted a HCF instruction in MMBasic. ;) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| DigitalDreams Newbie Joined: 03/05/2025 Location: United KingdomPosts: 17 |
Not asking for changes, just help and advice.... So voltage IS increased with higher click speed. I was going to remove the psram from one Pimoroni anyway to see how it then behaves vs the RaspberryPi Pico2. |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7800 |
I think you'll find it will help, but you may still not get full speed out of it. DVDD seems to be pretty critical and I'm not sure if Pimorini followed Raspberry Pi's specification for the supply (including getting the correct inductor and getting it the right way round!). At any rate, they've not produced a module that will overclock as fast as the Pico 2 yet AFAIK. The Pimorini boards do meet the Raspberry Pi spec though, I think, and may exceed it comfortably enough for most purposes. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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