Guru
Joined: 05/07/2020
Location: United StatesPosts: 478
| Posted: 04:01pm 20 Sep 2023 |
OK, can someone please look at this Frankenstein PICO and tell me if it could be used for the picoVGA? It is very feature packed Thanks.
https://tinyurl.com/5h25w7bx
Guru
Joined: 05/10/2019
Location: United KingdomPosts: 7034
| Posted: 04:30pm 20 Sep 2023 |
It looks like it should work as a PicoMite VGA if you connect external resistors to the appropriate pins. I can't be sure as I've not seen a schematic for it.
The on-board DVI isn't supported at all under MMBasic.
The PIO USB port isn't supported under MMBasic unless you wrote the USB code for the PIO.
You probably couldn't use a RPi Zero "hat" while running MMBasic.
It's cheaper to use an official Pico, which is also smaller. Yo can also find cheaper 16MB flash versions.
More Info here
I can't find a schematic, so whether the wiring of the PIO USB and DVI would cause a problem I've no idea. We don't know how the SD card is wired either, but you can usually manage that.
Edited 2023-09-21 02:49 by Mixtel90
Guru
Joined: 05/07/2020
Location: United StatesPosts: 478
| Posted: 04:46pm 20 Sep 2023 |
Thanks for the info. I have one of those 16MB PICOs. Not sure how to make that into a VGA.
Guru
Joined: 05/10/2019
Location: United KingdomPosts: 7034
| Posted: 04:51pm 20 Sep 2023 |
A "normal" pattern 16MB board can use the same connections as a standard PicoMite vor VGA. You don't need to do anything special apart from connect the resistors, sync signals and a VGA connector.
Guru
Joined: 18/11/2011
Location: United KingdomPosts: 3890
| Posted: 04:52pm 20 Sep 2023 |
Looks to be this Waveshare board but I don't see a schematic.
Also appears to have only a wiki template (i.e. no actual useful info).
John
Edited 2023-09-21 02:54 by JohnS
Senior Member
Joined: 18/02/2023
Location: United StatesPosts: 121
| Posted: 04:41am 21 Sep 2023 |
That web site is a scam.... (I am speaking about https://tinyurl.com/5h25w7bx )
It claims that board is $4.89 but when you try to buy it, the price has magically jumped to $10.61.
They are hoping you will just click on things without reading what the confirmation page is saying.
----------------------------
So after not completing the purchase (because they doubled the price) after an hour and a half they send me an email. They say the price is back down to the original $5 level.
I went ahead and finished the purchase. I'm hoping they actually send it.
Edited 2023-09-21 15:42 by EDNEDN
Guru
Joined: 05/10/2019
Location: United KingdomPosts: 7034
| Posted: 06:37am 21 Sep 2023 |
Personally, I'm not interested in buying a board that I can't find a schematic for. They don't tell you if any of the pins are being used dual-purpose. Waveshare say that *some* RPi Zero "hats" will work on it, but with no indication of which or why only some. Basically, there's so much info missing that I wouldn't bother with it.
Guru
Joined: 18/11/2011
Location: United KingdomPosts: 3890
| Posted: 06:44am 21 Sep 2023 |
I expect Waveshare will provide that info, just haven't yet.
John
Senior Member
Joined: 18/02/2023
Location: United StatesPosts: 121
| Posted: 11:41pm 28 Sep 2023 |
I just received the board I ordered. Included in the envelope was a link for the User Guide. They have the schematic for the board at this address: http://cdn.static.spotpear.com/uploads/picture/learn/raspberry-pi/rpi-pico/rp2040-pizero/RP2040-PiZero.pdf
The strange thing is they want to call this a 'Zero' but it has tons of stuff on it. So that doesn't really make sense.
The good news is it runs MMBasic with no problems. It has 15 MB of flash space. I guess that means I don't even have to figure out how to get the SD Card working for a while.
Edited 2023-09-29 09:48 by EDNEDN
Guru
Joined: 05/10/2019
Location: United KingdomPosts: 7034
| Posted: 08:33am 29 Sep 2023 |
They call it a Zero because it's the same physical size as the Raspberry Pi Zero, not because it's short of features. :)
Interesting circuit.
It's handy having the SD card working as it's useful for backing things up. There is a minor problem with this board though. I think you should be able to get the SD card working with
OPTION SDCARD GP21, GP18, GP19, GP20
The problem is that these are exactly the same pins that are used (along with GP16 and GP17) for the VGA output, which can't be changed. So you can have either the on-board SD card or connect a VGA monitor, but not both. The DVI output isn't supported under MMBasic.
Senior Member
Joined: 18/02/2023
Location: United StatesPosts: 121
| Posted: 08:49am 29 Sep 2023 |
Can you help me understand? In the DVI box of the schematic it shows (starting from the bottom) GPIO 2,3, 16, 22-29 being used for DVI?
How is there a conflict with the SD Card which uses GPIO 18-21 ? I must be missing something.
Guru
Joined: 05/10/2019
Location: United KingdomPosts: 7034
| Posted: 09:06am 29 Sep 2023 |
You can't use the DVI output from MMBasic at all. It isn't supported. You can use its pins for other things if they are available on the GPIO port though.
The on-board SD card is hard-wired to GP18, GP19, GP20 and GP21.
The PicoMite VGA system, used with normal Pico boards, uses resistors connected to GP18, GP19, GP20 and GP21 to produce the RGB video signals for the VGA port. GP16 and GP17 produce the sync signals. None of these pins can be changed.
Consequently, you could add the external resistors and connections to GP16 - GP21 and connect them to a VGA socket then connect to a VGA monitor, but you couldn't use the on-board SD card then.
If you wanted an SD card as well as VGA then one could be added *externally* to different GPIO pins.