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Forum Index : Microcontroller and PC projects : Random Reboot
| Author | Message | ||||
| Mark Regular Member  Joined: 26/11/2022 Location: United StatesPosts: 85 |
I am running PicoMite VGA MMBasic version 5.08.00 on a Raspberry Pi Pico (non-W). It is mounted on a Land-Board PicoMite 03. This provides a PS/2 keyboard, PWM sound, VGA, SD Card, RTC and a USB power input. I have a SD card in the SD card slot and am able to read and write it. I am using an (old) DELL PS/2 keyboard and a VGA monitor. All the features (RTC, SD Card, sound, keyboard and VGA) work. Here are the options SYSTEM I2C GP14,GP15 AUTORUN 1 COLOURCODE ON KEYBOARD US SDCARD GP13,GP10,GP11,GP12 AUDIO GP6,GP7 ON PWM CHANNEL 3 RTC AUTO ENABLE The PicoMite randomly reboots I've programmed an autorun progam to log reboots ' Log Reboot OPEN "a:\log.txt" FOR APPEND AS 1 PRINT #1 DATE$, TIME$, MM.INFO(boot count) CLOSE #1 PRINT DATE$, TIME$, MM.INFO(boot count) Sometimes the PicoMite reboots 2 times on power up. If I leave it powered on with no interaction it will reboot at random times. I've seen gaps of 30 minutes, but sometimes it will reboot twice within the same minute. I put a monitor on the power input and it seems steady. I loaded flash_nuke.uf2 before loading the firmware. Is this behavior normal or should I be looking for a hardware issue? Is there anything I can do to further troubleshoot this? I also tried running version 6 on a Pico 2 using the same PicoMite board and experienced random reboots (which is why I went back to the Pico and version 5.08. Another thing, with both versions, sometimes after a reboot, the PicoMite doesn't respond to the keyboard. Unplugging and replugging the PS/2 connection for the keyboard, sometimes more than once, will get the keyboard working again. Thanks, Mark |
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| matherp Guru  Joined: 11/12/2012 Location: United KingdomPosts: 10244 |
Typical symptoms of an inadequate power supply and/or cable. |
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| Mark Regular Member Joined: 26/11/2022 Location: United StatesPosts: 85 |
Thanks for the reply. I did try a different power supply and cable - same issue. I did some more testing and I think the metal case is the problem. If I touch the case or even get my hand near it, the PicoMite reboots. I took it out of the case and the problem seems to have cleared up. The solder mask on the ground plane was resting on the metal case. While testing, something changed with the Pico. When the video comes up the first two columns of characters are off the screen to the left. I nuked the flash and refreshed 5.08. The video is still off. I reset the monitor, same thing. I tried a different Pico and the video is fine. Any idea what happened? Mark |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2611 |
Another possibility is leakage or static affecting the RUN (reset) pin. A 100nF cap. to ground or/and 10kΩ resistor to 3.3V usually fixes it. |
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| Mark Regular Member Joined: 26/11/2022 Location: United StatesPosts: 85 |
A 10k Pullup didn't help. I changed the case from aluminum to 3D printed plastic and the PicoMite is solid now. Mark |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7869 |
I shouldn't think that a metal case in it's own right would cause a problem. However I would look at the mountings. Don't assume that you can use metallic fixings in the Pico's mounting holes. At the very least you should use plastic washers between the PCB and metal pillars, preferably with nylon screws. Please note that if you connect a metal case to GND in any way then you can have a problem! They should only ever be connected to mains earth. GND is not usually connected to mains earth in a switching power supply other than via a capacitor to reduce EMI. That little capacitor can pass a tiny amount of mains current out onto GND, so if you then touch the metal case you can get a tingle from it in some circumstances. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| ville56 Senior Member  Joined: 08/06/2022 Location: AustriaPosts: 220 |
was he aluminum case connected to ground or left floating? Gerald 73 de OE1HGA, Gerald |
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| Mark Regular Member Joined: 26/11/2022 Location: United StatesPosts: 85 |
The case was not grounded. The PicoMite board's ground plane was in contact with the case. Edited 2024-12-25 21:52 by Mark |
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| ville56 Senior Member Joined: 08/06/2022 Location: AustriaPosts: 220 |
Well, was just looking at the different variants of the original Pico, there are no ground pads with the mounting holes for the non-Wifi versions .... One could do that with the Wifi versions as they have groundpads on the antenna side, but then again Wifi in a metal case  ... IMHO there is no way to use the mounting screws for ground contact. So one has to use dedicated wire(s) for making a reliable ground connection with the case.73 de OE1HGA, Gerald |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7869 |
Not necessarily accurate. Metal mounting pillars, washers and screws mustn't exceed 4mm across their greatest dimension, and that's if they are centred on the hole. If they are off-centre then the limit is correspondingly smaller. Also, we aren't talking about a reliable GND connection unless it's deliberately been wired so, we *could* have a case where a single GND connection causes the crash and it may only be intermittent. There are all sorts of reasons for random reboots: Two points on the board could be shorting via metal pillars if the widest dimension of a pillar is 4mm or more, A single point on the board could be shorting to a case connected to GND A single point on the board could be shorting to a case connected to mains earth (possibly via a capacitor in the power supply) The power lead can be too resistive The RUN input could be getting noise (fit 100nF to GND) Suffice to say, random reboots are not to be expected unless something very odd is happening. .................. We must not get diverted here. The problem may not be in the Pico's fixings at all. It's plugged into a Landboards 03 module, and I have no knowledge of that. It could be that it uses the top and bottom ground planes as supplies - or anything. To find the problem you have to look at the 03 module and how the fixings work on that - we only know about the Pico. Edited 2024-12-26 19:04 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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