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Forum Index : Microcontroller and PC projects : PicoMite: PicoGAME VGA development
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| Tinine Guru  Joined: 30/03/2016 Location: United KingdomPosts: 1646 |
Sure: More I/O available and more compact I got a bit nervous because Pimoroni were sold out. I found some at The Pi-Hut. I contacted Pimoroni about the shortage but I have been assured that it's only a delay with the PCB and that they will have more available within a couple of weeks. Craig |
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| Tinine Guru Joined: 30/03/2016 Location: United KingdomPosts: 1646 |
Darned duplicate Edited 2022-05-26 01:04 by Tinine |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3155 |
Thanks. Looks really useful if you really need the space. I don't anticipate that I will. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6825 |
Personally, I think it's rather specialised. You pay over twice as much, get a much more difficult package to work with and only gain 4 I/O and some more flash for your trouble. Ok, it's only half the board space, but by the time you've managed to get traces away from it you may not have gained as much as you expected. I can see that there are applications where it might have advantages, but I don't think there are many. If I had a good commercial application for the RP2040 - something with a reasonable number of sales - I think I'd work with the basic chip and have the boards made with it already mounted, together with clock and flash. The boards might be multi-purpose to a degree. Come to think of it, that pretty much describes the Pico. :) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Tinine Guru Joined: 30/03/2016 Location: United KingdomPosts: 1646 |
When one is proactive and faced many curve-balls over the years, one sees the value of 4 extra pins per MCU:   "Hey but we have such-and-such...are you guys compatible?" Been there  Craig |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3155 |
When and how is the 3v3.EN line used? PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| Tinine Guru Joined: 30/03/2016 Location: United KingdomPosts: 1646 |
My understanding is that; tying it low, disables the onboard 3v3 switcher. In my case, it caused the USB to stop working, even though I had an external 3v3 to the 3v3 pin.  Craig |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6825 |
Grounding 3V3EN shuts down the on-board SMPS that's reducing 5V to 3V3. To get things running you then need to power the Pico and everything else from an external supply. I must admit, I hadn't considered the USB port stopping working - I'll have to look at that. 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: 3155 |
Thanks, Mick. So if you are powering from an external 5V through VSYS (though a diode, e.g. SR260) then you only need to pull down 3V3EN if you also are powering through the USB connection? I'm applying 5V through that SR260 schottky diode with no USB connection and, with OPTION SERIAL CONSOLE 1,2 I have serial console access. Per my DVM, I have 3V3 on 3V3OUT, as I want. I don't need to worry at all then about 3V3EN? PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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thwill Guru Joined: 16/09/2019 Location: United KingdomPosts: 4047 |
Are you saying that you can't use the USB for a serial connection to the Pico on the v1.4 board? I don't think I'll bother finishing the one I have in progress if that is the case, or is it hackable? Best wishes, Tom Game*Mite, CMM2 Welcome Tape, Creaky old text adventures |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3155 |
No, I'm saying that I don't want to use the USB console--I want to use serial console and power through VSYS--and not on Mick's PCB. (Sorry for O.T. question, but this is the most active picomite thread, and I think Mick has experience using VSYS.) PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| Tinine Guru Joined: 30/03/2016 Location: United KingdomPosts: 1646 |
Please don't base anything on my findings because I was on with something else and so only did the basic test. Could easily have missed something. Craig |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6825 |
*if* there's a problem it only means that if you use the linear regulator the usb console won't work. There's no problem if you use the smps on the Pico or if you use a higher voltage input and regulate down to 5V for VSYS. I'll check later today. the pc usb will provide 5v for that side, it's just a case of does the pico need 5v to talk back to it? Edited 2022-05-29 02:45 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Tinine Guru Joined: 30/03/2016 Location: United KingdomPosts: 1646 |
Oh, that was something else I tried. External 5v AND external 3v3. My PC USB is a breakout and so I disconnected the 5v to leave the data lines and the GND. No go  Craig Edit: Oh, and W10 acknowledges that a USB connection has been made but complains that it doesn't recognise it...no-show in device manager. Edited 2022-05-29 03:08 by Tinine |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6825 |
I've just had a think and a play. With 3V3EN low and the smps disabled the system works fine powering 3V3 via the linear regulator. With the external supply off (no 5V) nothing works if you connect the Pico to a PC via USB. VBUS and VSYS are present but, as the smps is disabled there is no 3V3 to the RP2040. If you then connect the external supply *as well* then the 3V3 supply is reinstated via the linear regulator and all is well, the console will work. I briefly considered feeding the linear regulator from VSYS to make things automatic, but it really needs something to prevent the smps back feeding into the reg (and vice versa) if one has a higher voltage than the other. I ruled out diodes as impractical (we haven't got a diode between the smps and the 3V3 rail) so it would have to be solder blob links. Edited 2022-05-29 04:20 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: 3155 |
Thanks for the clarification. I appear to have my setup working as I wish in accordance with what you have described--5v external power via VSYS + diode, serial console, nothing on 3V3EN, 3V3OUT providing power (I guess through the onboard switch mode 5V-3V3 regulator (and I'm not concerned with ADCs)). PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6825 |
Yep, if the smps is enabled you can leave off the regulator as it isn't needed. The USB port will provide power to the system as expected. On the 1.4 boards you have to blob the 5V link and cut the 3V3EN link to change over to the smps supply.. 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: 3155 |
Just received my "pear" pcb from JLC. Anything particular I should be aware of?  PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6825 |
Ah - that seems to be the first one to be built. :) I don't think so. I did the usual tests in Sprint Layout and didn't spot anything obvious. Looks like a nice board. If you use 90 degree connectors for the GP ports then the PICO1 connector is flush with the edge of the board, the one for PICO2 projects out through the front panel of a Hammond box. The SDcard socket for PICO2 will probably have to be soldered to the board without a socket if you are going to use the LCD display, otherwise I think it will obstruct it. 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: 3155 |
Thanks. While I'm gathering parts for the pear pair, I need an as small as possible picomite PCB breakout. Since I have 5 of these pear PCBs and don't expect to need more than one, is there any reason I can't just cut out the PICO2 along the lines shown in red below, and use the 20x2 connector, powering either through USB or VSYS?  PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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