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Forum Index : Microcontroller and PC projects : Need advice PicoMiteHDMI PS/2 PCB layout
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| Bleep Guru  Joined: 09/01/2022 Location: United KingdomPosts: 625 |
Could it be related to, if you type quickly and you haven't quite released the previous key before the next key makes contact one or other of those keys gets missed? Not sure how a USB keyboard would handle that? If indeed it's a problem at all, I'm away in Ironbridge currently & can't experiment, easily. |
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| PhenixRising Guru Joined: 07/11/2023 Location: United KingdomPosts: 1360 |
I was there with the GF, a few years ago. We stayed at Ye Olde Robin Hood Inn. For the first couple of days, we were sat out front, looking at a bridge and I'm giving her earache about how this bridge is nowhere near as old as they claim....turned out to be the wrong bridge  The third day, we discovered the actual Iron bridge |
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javavi Guru Joined: 01/10/2023 Location: UkrainePosts: 460 |
@Amnesie I think it is necessary to reserve one port from GP0, GP8 for selecting the PMRAM chip. At the moment, an additional PMRAM chip can be easily soldered on the second floor over the flash chip on Chinese clones of Pico 2 RP2350. For example, I run PicoMite HDMI on a murmulator board with an installed Chinese clone of Pico 2 from WeAkt with a soldered PMRAM over the flash chip. Also on this board, both video outputs HDMI and VGA are connected in parallel to choose from, and it is surprising that one does not interfere with the other at all. Also, three ports are allocated for sound, which allows you to connect an I2S DAC or use PWM to choose from. Here is a block diagram as an example of port distribution:  Edited 2025-07-03 22:57 by javavi |
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| javavi Guru Joined: 01/10/2023 Location: UkrainePosts: 460 |
For VGA video output, we also have a hardware switch for the PicoMiteVGA/Windows 16 color palette.   |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 5058 |
Hi Amnesie, I would personally connect the PS2 mouse to GP20/21. This frees up the GP27/28 pins. You loose 1 COM port, but you gain access to SPI2. Your design has 2 COM ports and NO SPI possibility. The choice is a balance between applications. You are into Geiger counters and may prefer COM ports over SPI. That I cannot judge. If you decide (as javavi suggests) to piggy back a PSRAM , you can use GP0 as a chip select, and (in that case) use GP28+GP1 as a COM port. Volhout Edited 2025-07-03 23:41 by Volhout PicomiteVGA PETSCII ROBOTS |
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| Amnesie Guru Joined: 30/06/2020 Location: GermanyPosts: 639 |
Hi Harm! Thank you for this idea with the SPI, I didn't thought about that. This may be a good idea to preserve one SPI option! Thanks for this hint! @ javavi Wow this looks interesting, I will have a look at your "Murmulator". Greetings Daniel |
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| javavi Guru Joined: 01/10/2023 Location: UkrainePosts: 460 |
Murmulator 2.0 (M2) is just a development of the Murmulator (M1) platform for emulating retro computers to use the capabilities of Pico2 RP2350 (HDMI, PSRAM). The photo shows the M2 version 2.0 board, which has a Chinese clone of Pico2 RP2350-Plus with a soldered PSRAM chip, the CS output is connected to the GP8 port via a jumper that allows you to disable the use of PSRAM.  |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10239 |
Are the 2.0 gerbers available anywhere? The website only seems to include V1.1 |
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| javavi Guru Joined: 01/10/2023 Location: UkrainePosts: 460 |
Project PCB v1.0 of the Murmulator 2 (M2) for KiСAD 8.0 M2_38NJU24_1.0.zip This is the first version of the board with experimental moments and that's why the author did not post it on his GitHub (he rarely uses it and at the moment he can't go into it, probably he's too lazy)). In general, the board works and I use it perfectly for PicoMiteHDMI even in VGA with an installed adapter. Edited 2025-07-04 03:17 by javavi |
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| javavi Guru Joined: 01/10/2023 Location: UkrainePosts: 460 |
@matherp Here are many more Murmulators from our Greek friend https://rh1.tech/ https://rh1.tech/ |
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| Amnesie Guru Joined: 30/06/2020 Location: GermanyPosts: 639 |
Exactly! Thats why I'm not saying that Peter needs to "fix a bug", instead I said that I solved it "my way" with the converter by "NoOne" right from the beginning. I just wanted to explain WHY I am not using the USB variants. It's my decision, period. The worst thing is: this whole thread is 95% offtopic. Hmm, I know a person who likes to insist on staying on topic (especially if there already IS a thread for this.. Thanks to the few contributions, especially Harm for the hint with the SPI.No - back to reality. As one can read; I am really disappointed how this came out (and it is not the first time). With this attitude I have lost all joy to work on this any further for now. I am out. Why not the first time? I am even not the first one who is getting "censored" by Peter: just ONE example with the user: Link Or Here: Not in open forum? Ah ok, I get it! I should state it in a closed hidden imaginary forum, right? ... Or better don't say anything at all. Ah, this is how things work for you. Ok. ... and and and so on. That's also a way to destroy all the joy. I think this is now my new motto: I am convinced that most of the people have no problems, really! But at least two users have the exact same problems and they (including me!) are not complaining at all. But it is censored to say there is a flaw... Sorry next time I have it mind and write something like this: There are certain circumstances under which the USB firmware may not function correctly with some keyboards (it seems). This malfunction, if it is one, could possibly be due to a bug, but this statement is not suitable for drawing conclusions. Nor does this statement claim to be accurate or complete. Can an Admin please close this topic? Greetings Daniel Edited 2025-07-04 07:48 by Amnesie |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7864 |
I wonder... A USB-A Host output should have two 5K1 resistors from the D+ and D- lines to ground. The Pico does not have these. If you want them you have to fit them. I've never needed them. A USB 2.0 (and I think USB 1.0) client should have a 1K5 resistor from D+ to VCC to tell the Host that it is a USB client device. Note that the Pico USB socket is in Host mode when the USB firmware is loaded, not OTG. That's different and isn't supported. It will support a *non-powered* USB hub. If you are connecting via a hub then, in theory, it should have the 1K5 resistor internally if it's a USB-A but not if it's USB-C, which uses the CC lines. The Pico doesn't, as far as I know, support USB-C hubs properly at all as it's a USB 1.0 system. You may have problems with anything USB-C unless it's connected via a hub to give a USB 1.0 or 2.0 connection to the Pico. I wonder if the difficulties are due to some or all of the above items? Most people use a micro USB to USB-A hub, direct or via an adapter (or built in as a chip or module). There are no USB-C facilities used. Note that even clones with a USB-C socket still use it in USB-A mode, it's not a true USB-C connection as the RPxxxx can't handle that. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| ebbandflow Regular Member  Joined: 31/08/2023 Location: United StatesPosts: 42 |
Daniel, as you noted I have experienced the exact same issue multiple times. I have tried multiple keyboards, picos, firmware, repeat settings, etc. and ALWAYS find dropped keys and slow response with the USB firmware in comparison to stock firmware with PS2 keyboard attached w/ no hub (or USB keyboard to PS2x2pico). It's not a wiring or voltage issue here either but it seems we'd need a reference design to be taken seriously? Has anyone got one for sale? /s |
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| PhenixRising Guru Joined: 07/11/2023 Location: United KingdomPosts: 1360 |
I think a few of us would prefer to get to the bottom of the true cause. One of the many cool things about this community  IMO. MMBasic is the best thing to happen in the MCU world due to continually pushing the boundaries by some very dedicated individuals. |
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| dddns Guru Joined: 20/09/2024 Location: GermanyPosts: 490 |
For me, the responsiveness with an USB keyboard is ok, if I set the values like I posted last page. If I'm using the default, I'm loosing key presses as well. But there is no word if he even tried that. @Amnesie Look, how you "argue"! This is purely offending and almost non technical. This was the point, where I lost the fun.. |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 5058 |
Hi Daniel, I agree this thread has derailed. But I do not want to open a new thread on USB keyboards, and the problems some are having. First: about statistics: this is a small community, and even this small community is using picomite on several different platforms. If you realize that there may be only 4-10 people actively using USB keyboards daily (-or- often) enough to ensure USB is actually 100% to satisfaction. In that balance, 2 that have a serious problem are not to be ignored. And this community has proven there is always help for those who ask. The different platforms: please be aware that the current release (6.00.02) is the last with such a big choice in platforms. If you look at Geoff's website and the user manual, it is very well possible that the 2040 platforms remain PS2/VGA (if there are any new releases) and future releases for the 2350 may be HDMI-USB only. With that view you may be betting on the wrong horse with PS2 in the long run. I understand you feel frustrated with this, have the feeling this issues has been ignored, and want to make 100% clear you have decided to use the work around. But.. the first post you made this clear was sufficient. You felt attacked by the people at the forum, the dominance Peter has, deciding what he can fix and when, and felt cornered. Totally understandable. But .. throwing with mud (even when the mud is well founded) does not help anyone. It only brings negative energy. And this forum was always proud on it's positive energy. Help us get the positive energy back. Let us help you solve this problem. Best regards, Harm (Volhout) Edited 2025-07-04 17:11 by Volhout PicomiteVGA PETSCII ROBOTS |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7864 |
I would certainly like to know what's going on here. Resorting to a 3rd-party PS2 system cause you find a problem that no-one else is seeing won't lead to any fixes. If you want to see your problem fixed then help with the fault finding rather than saying that there is a fault. If you aren't bothered about fixing it then stop moaning that there is a problem. People that can't see the problem can't look for it. They haven't got your hardware. It could even be a faulty Pico or firmware flash. MMBasic *appears* to be fine. If it wasn't then surely all users would see a problem? That leads me to think that we are looking for a hardware incompatibility somewhere. I'd look from that angle first so that it can be ruled out. First, the keyboard *must not* have programmable keys, displays, knobs, programmable RGB lighting or built-in hubs. If it has then nothing is guaranteed and you may as well stop there. It won't get fixed for those keyboards as they are non-standard and may not fully comply with the basic USB spec that TinyUSB uses, even if they work perfectly on Windows. Second, you should at least try a USB interface to the Pico that complies with the USB spec for a Host. i.e. the 5K1 resistors must be fitted from D+ and D- to GND. I know no-one else uses them, but we have to assume they are needed before we can rule them out. The best place to fit them is on the Pico itself. USB connections *must* use proper leads in good condition, flying wires are not compliant with the USB spec. Third, the 5V supply to the USB devices must come from VBUS. VBUS and VSYS can be linked together. The 5V supply *must* be good. If you are using a laptop then at least be certain that it has USB compliant power available (500mA). Check that you have 5V at the Pico, don't assume it. Unless you are only connecting a keyboard then you will need an *unpowered* USB hub. A powered hub will back-feed power to VBUS and we can't specify that supply. The hub should ideally plug directly into the Pico, but you may have to use an adapter of some sort. Try a different Pico. Don't assume that you are using a good one. Likewise program it with a new download of the firmware, not a possibly corrupt one that you used last time. Test with only minimal OPTIONs set. You can add others later, re-test and see if one causes the problem to appear. Once you know for certain that the hardware is right it *might* be time to look at the firmware, but you *must* try the repeat and delay arguments for OPTION KEYBOARD before doing anything else. They are intended to "tune" the keyboard to your preferences. Don't assume that the defaults are right for you. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4038 |
I thought it was a VGA version which (for you and at least one other) there's a problem? Above, you're saying the HDMI also has the (claimed) problem? (Your wording isn't saying it might have the problem, it's saying it does have it.) Also, which of the VGA versions of hardware and software do you mean? (I just cannot follow the scattered hints and complaints about h/w and/or s/w, sorry.) You have used the OPTION KEYBOARD settings about delays/etc appropriately? So far I just don't see any way people can use the right h/w & s/w to check whether they also see the issue. John |
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