Guru
Joined: 05/10/2019
Location: United KingdomPosts: 9179
| Posted: 09:43pm 18 Feb 2024 |
The USB version works like this:
An incoming 5V comes from an external source - the console is a possible place. The PicoMite VGA Basic board also has a barel jack socket which is suitable. Only use a single source of supply though.
The console is connected via a USB-TTL converter with the TTL side on GP8 and GP9 instead of the PS2 keyboard. These pins are configured as a serial port at 15.2kbd by default. The 5V rail can be taken from this converter.
Normally there is a forward-biased diode from MBUS to VSYS on the Pico, to protect the USB connection from a supply on VSYS. In this case we don't want that diode as we are going to put 5V out, so you can power the Pico via MBUS or power via VSYS and link VSYS to MBUS to short the diode out.
The Pico's USB is fed to a USB keyboard or a passive USB hub (not a powered one). You can't connect this USB to a PC now as there is a danger of damaging the USB port on the PC. You will need a USB-A female to micro USB male adapter to connect to the Pico's USB.
The USB hub can accept keyboards, mice and some game controllers. I got a very cheap 4-port hub from ebay and it works fine.
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It's also possible to make an adapter (as shown earlier) that will accept a USB keyboard and convert the signals to PS2 to feed the PS2 input. This uses the standard software so USB mice and game controllers are not supported unless people write special software to do it. If using this method then the adapter Pico is simply powered from the same source as the main one.
Edited 2024-02-19 07:49 by Mixtel90