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Forum Index : Microcontroller and PC projects : I have 2 questions
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Plasmamac Guru  Joined: 31/01/2019 Location: GermanyPosts: 579 |
1. is where a device which works as sd card but with usb stick. 2. if i put h/sync and v/sync from 2 picos together and move the pixeltakt from one for sync can i get a screen with booth pico vga ? Thx Plasma |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7937 |
1. They don't work in the same way. Nope, I don't think you can do that. 2. Nope, sorry. The sync signals are related to the video signal output so the sync on one pico can't work with the video of another. In fact, you could possibly damage something if you linked the sync pins together. Your monitor certainly won't display anything sensible. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
You need a video mixer, but they tend to be expensive and HDMI for the most part.($400 or more) Have not found any VGA ones. Smoke makes things work. When the smoke gets out, it stops! |
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| Plasmamac Guru Joined: 31/01/2019 Location: GermanyPosts: 579 |
@1 : i mean a bidirectonal bridge .maybe a micro between sd port and usb port . @2 : isnt the pico pio fast enough to create a extra sync signal between booth picos ? Plasma |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7937 |
1. There are spacial chips that handle USB memory sticks via SPI. They aren't supported by MMBasic - I'm afraid it's up to you to sort out the interface software and find out if they work. :) Look for something like the CH375B or MAX3420E. Note that, as you'd (probably) still be using the PicoMite file system you don't gain any extra capacity. You could program something that can handle USB sticks, say, a Raspberry Pi, as an intermediate system and connect it over SPI but it's a lot of messing about. Why store to USB stick anyway? It seems counterproductive to me. 2. In theory you could use one Pico to be the clock source for the other. That would make sure that they stayed synchronised. Whether you could output a fast enough clock I've no idea. There is no way to do this from MMBasic - it's low level stuff on the RP2040. Timing for the VGA output is pretty critical (it's handled by a PIO, not in software) and I doubt if you would manage it anyway. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2442 |
hi Plasmamac, i'm afraid that what you have written doesn't quite make sense -the meaning may have been lost in translation from german to english. 1. are you after a device that has an SD card at one and and a USB plug at the other, so that you can plug it into an SD socket on a pico, or into a USB port on a PC? do you want the pico and the pc to be able to write to/read from the card at the same time? what exactly do you want to use this for? 2. do you want to have two picos displaying on the same monitor, with either the outputs 'side by side', or one above the other? some TVs from the 1990's-2010's could do something similar to this with a 'picture in picture' feature, but it was just a gimmick that has fallen out of favour (like 3D TV did). or do you want, for example, one pico to produce the even numbered lines, while the other produces the odd numbered lines? again, what exactly do you want to use this for? could the same thing be accomplished with two copies of Tom's port of MMB4L running on a pi zero? cheers, rob :-) Edited 2022-03-11 22:27 by robert.rozee |
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| Plasmamac Guru Joined: 31/01/2019 Location: GermanyPosts: 579 |
HI , sorry to be unclear : 1: i like to use an usb stick and not an sd card . a device which simulate an sd card but store the datas to a usb (stick.) i have some sd card using devices but dislike the handling.. i mean even arduino can read and write sd cards . now we need a driver for usb for. 2: using 2 pico (because we have the source code and its cheap if i blow one). booth on one monitor at the same time. i will create an overlay (time/date or something). (such like old TV's) no framegrabber or something. thx Plasma |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2442 |
1. a card something like this?  see this news item from 2005: https://www.dpreview.com/articles/3783318788/sandisksdflip and earlier, in 1999, there were similar CF cards from Lexar: https://www.dpreview.com/articles/2745487673/jumpshot as far as i am aware the idea never really took off, and i am not aware of anything similar available today. this is not to say you couldn't 'roll your own'; you just need to combine an SD card with a card reader + relay. when the relay is energized (from the USB 5v rail), the SD card is connected to the reader's electronics. when USB power is absent, the relay drops out and connects the SD card contacts to a cable tethered SD 'plug' that is plugged into your pico. while fitting this into a package the size of the Sandisk solution would be difficult, fitting it all onto a PCB the size of a stick of gum could be done. 2. combining two VGA signals is doable with available electronics, but expensive! the cost would far exceed the cost of a couple of picos. however, in theory i could see it being possible to have a pico (or similar) take Hsync and Vsync inputs, and using these generate RGB data that would overlay an external VGA signal. it would, however, require quite some development work to create the routines to do this, including creating new PIO code. i remember back in the (early?) 90's a friend created a system for adding text over a video feed using an Amiga 1000 computer. cheers, rob :-) Edited 2022-03-12 01:06 by robert.rozee |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7937 |
I think plasma wants to use a USB stick *instead* of a SDcard, but connected to the same SPI and using the same system. I'm pretty convinced that this is impossible without something else between them, either a computer inits own right (such as a Raspberry Pi) or one of the specialised chips that I referred to earlier. The flip RAM had one RAM chip that was accessed by either the SDcard connector or it could be plugged into a USB port - not the same thing, although it might be usable here it can only be connected to one device and you can't use it with any USB stick. You have to bear in mind that the Pico doesn't contain any sort of video processor hardware or firmware. The fact that we have VGA at all is because of using the 2nd CPU core and a PIO in a clever way. Normally a specialised video chip (as the Amiga 1000 had) would handle overlays. Buy a second monitor - it's a lot cheaper than a half decent video mixer. :) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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thwill Guru Joined: 16/09/2019 Location: United KingdomPosts: 4311 |
I have a no-name, no-serial number thumbnail sized USB dongle that allows me to connect a microSD card to a USB port, that's not what we are talking about is it ? EDIT: Ignore me, that's just a USB card-reader isn't it, no matter how small it is  EDIT 2: As it happens I have one of those flip devices (I knew I recognised it) sticking it out of an old Panasonic TV in my bedroom - no idea if it works. Best wishes, Tom Edited 2022-03-12 01:53 by thwill MMBasic for Linux, Game*Mite, CMM2 Welcome Tape, Creaky old text adventures |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7937 |
I think he wants the exact opposite, Tom. Some way of plugging a normal USB stick into the SDcard socket on a PicoMite. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Pluto Guru Joined: 09/06/2017 Location: FinlandPosts: 375 |
I like to recycle as much as posible. My PicomiteVGA is connected to an old LCD screen from a scrapped IBM laptop.  Inplanted on the display's backside in the enclosure of an old digibox.  The main board with PicoMite and external connection circuits are bolted to an old DVD envelope.  NB:keyboard not yet tested. Fully functional @total investment of less than 30USD (Picomite ca $6 + LCD driver ca $21 + SD card holder $0.60 incl freight from China). Just now connecting to a Geiger-tube module (taken into operation after resting several years in my backshed) for monitoring eventual changes in radiation coming from south-east.  Still normal background levels on my monitor as vell as on the official measurements. Thanks to MMBasic it is so easy to rapidly implement useful things on demand. Sorry if I diverted a bit from the original course of the thread! |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7937 |
I hope you're ashamed of yourself - spending so much on a SD card holder when you could have soldered wires onto a full size SDcard adapter and stuck it down with a glue gun. ;) That's really good - I'm impressed! I have a couple of old laptops (not IBM), it might be worth investigating their screens. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Pluto Guru Joined: 09/06/2017 Location: FinlandPosts: 375 |
I have ordered the LCD driver boards from "Yqwsyxl LCD parts Store" on Ali Express. Just send them the LCD model number and they will propose suitable driver boards for you. Fast response and fast delivery (2 weeks). |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7937 |
Thanks. :) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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