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Forum Index : Microcontroller and PC projects : PS2 Mouse freezes in CMM2 (Gen 1)
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| andrewq Newbie  Joined: 18/10/2022 Location: AustraliaPosts: 7 |
Hi, I just completed building CMM2 (Gen 1) from parts supplied by Silicon Chip magazine and Waveshare module. Loaded it with 5.07. I did a burn in test overnight running graphics, sound, games etc for 24 hours. Its all good and stable. Later, I connected a PS2 mouse based on the instructions (from the manual) using the required 4.7k Ohm resistors etc. and connected the PS2 pinout to the pins on the back of CMM2 as per instructions. Mouse works 99% of the time. That is, while using it in FILES and EDIT mode, the mouse freezes (along with system) at some rare points. For example, the freeze up happens when I click on the MISC folder in the WELCOME TAPE directory. Each time and everytime. When this happens, the red LED lights up permanently. The only way to continue is to reboot the system. Also, everyone once in a while when I go into EDIT, I get a "mouse time out" error. This happens intermittently, like 1 in 20 times. On the other hand, when I run a Basic program (e.g. the fractal demo) that uses a mouse to zoom in and out, the mouse works perfectly. My guess is (1) I may have a h/w fault in CMM2 that I may have unknowlingly introduced during my build . Blame it on my poor soldering skills. Or (2) there may be some undocumented interrupt conflict that I am unaware of, but I am hoping that someone may have already found a solution to this. Please help. Andrew Edited 2023-08-22 22:28 by andrewq |
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Geoffg Guru  Joined: 06/06/2011 Location: AustraliaPosts: 3194 |
Hmm... that is a hard one. I have not seen that problem and I don't remember anyone else reporting it either. It sounds like something related to a marginal voltage level or noise on a signal line or power supply. If you have an oscilloscope it might be worth doing some detailed checking. Also, try another mouse (you never know). Geoff Geoff Graham - http://geoffg.net |
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| circuit Senior Member  Joined: 10/01/2016 Location: United KingdomPosts: 245 |
Geoff's prompt on marginal voltage level sounds similar to a problem that I had with USB keyboards on the MZ series. The problem was that the power leads inside the USB cables were inadequate for the power required. I would suggest starting by checking the voltage on the mouse power line under various conditions. I found that when the SD card was read the voltage to the keyboard dropped below operational standard and the keyboard failed. |
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| andrewq Newbie Joined: 18/10/2022 Location: AustraliaPosts: 7 |
Thank you Geoff and Circuit, Yes, indeed I suspect it has to do with power load and may have something to do with my temporary setup (as pictured). I have not used a genuine PS2 mouse, but a rather dated USB mouse with an adapter. Yup, I have been hoarding a boxful of old PC parts that I have been hoping would come in handy one day - just like this one, but.... Anyway, I tested nine old USB mouse (all at least 7-8 years old), from which 4 worked with the PS2 adapter and the rest did not. From those that worked, all gave the same similar freezing up problem when used within EDIT and FILES. The freeze up only occurs when it tries to access the SD drive. I have not made any measurements as Geoff and Circuit has suggested for the time being, as I have placed an order for a native PS2 mouse via Amazon. Still waiting for it to be delivered. And if still gives the same problem, I will follow this up by breaking up the CMM2 box and have a proper look inside. As an aside: I am not sure if the difference between how the USB and PS2 is triggered has to do with the freezing up problem. That is, while the USB signals are polled (round robin), the PS2 works on actual interrupts. And because I am using an adapter, I am unsure if this is messing up how CMM2 handles the incoming mouse clicks. This is my 2-cents worth for now. I will update this post once I have tested it with the new PS2 mouse.  |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6798 |
You can't, unfortunately, assume that a USB mouse will work into a PS/2 port even with an adapter. Some will, some won't and some are iffy. What are the connections to the mouse? Are you running it from 3V3? Not all mice need pullup resistors, try it without. Edited 2023-08-27 00:49 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2136 |
Peter has mentioned many times that the 3.3V supply to the SD card often needs decoupling. A 2R2 resistor in series with its 3.3V line and 10uF ceramic or tantalum cap. across the SD card supply pins. You could try the same setup for the mouse supply too. Edit. Mouses that work with both USB and PS/2 effectively have two separate controllers in them, choosing one or the other depending on what signal voltages they see at power-up. I don't think they try to use USB protocol through the PS/2 connector, so the PS/2-only mouse may well have the same issue. Edited 2023-08-27 08:44 by phil99 |
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