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Forum Index : Microcontroller and PC projects : Pico Computer 3: Full house MMBasic build
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| ville56 Guru  Joined: 08/06/2022 Location: AustriaPosts: 641 |
from ther schematics: BLM18EG471SN1D it is available from RS, DigiKey, Farnell and other big distris. But basically this should be replaceable with a good old ferrite bead over a straight wire or with 2 or 3 turns if you don't dare to solder tiny SMDs. It's purpose is to avoid RF leaking back from the Wifi module into the supply which may cause all kind of interference in other parts of the PC3. It resembles a high impedance at 2.4 GHz and only 0.21 Ohm at DC. There is no guarantee that this will remedy the noise but it may contribute to reduction as stray RF is always a source of joy .... 73 de OE1HGA, Gerald |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 9220 |
Adding inductance can also be a source of "joy" :( There will be a resonant LC circuit formed with the stray (or intentional) capacitance after it, which can just as easily make things even worse. Before incorporating LC filters (especially at high frequencies) you really need to know exactly what frequencies you are filtering, how the filter is going to handle them and be able to analyze the results. Generally speaking it's preferable to simply make the supply rails as solid as possible, short lengths and good local decoupling. Avoid aluminium electrolytics (they are inductive). Tantalum caps are much better, as are MLCC, which can have the advantage of tiny lead lengths. Mick Zilog Inside! nascom.info for Nascom & Gemini |
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| mozzie Guru Joined: 15/06/2020 Location: AustraliaPosts: 468 |
G'day, Just for the sake of testing, decided to try plugging / connecting a heap of things onto the PC3 running RC1 to see how it went: Bluetooth Keyboard / Mouse combo Bluetooth serial HM10 module (COM7) Bluetooth speaker (Milwaukee M12) USB Wireless Keyboard / Mouse combo FT232 TTL / Serial converter (COM3) 7" HDMI Monitor with 10 point CAP-Touch screen Music on SDCard Running 1024 x 600 in mode 3 The FT232 has RX-TX looped to send back anything it receives. The HM10 serial module is connected via another FT232 to the PC. A slightly modified version of the PUMP-TEST program to send all recieved keypresses to COM3 and then from COM3 to COM7 via interrupt routines Anything received from COM7 (PC) is sent to COM3 via interrupt routine and then is sent back to COM7 and back to PC Play audio from b: to BT speaker And it all just works  Typing on touch screen / USB keyboard / BT Keyboard / Console Keyboard all working together. Touch Screen / USB Mouse / BT Mouse all working with the Pump-Test GUI system. Music keeps playing, no gaps noticed Whilst I guess this is not stressing the processor it shows the peripherals are pretty steady. Only issue so far is getting enough 5V current to power everything. Overall very impressed with the PC3, my thanks to Peter and everyone else involved for making this possible  Next test is Bluetooth and Stepper system to see how that goes. But thats tomorrow (ok, later today), its time for bed  Regards, Lyle. |
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| PhenixRising Guru Joined: 07/11/2023 Location: United KingdomPosts: 2097 |
Any chance of a pic, please? |
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| mozzie Guru Joined: 15/06/2020 Location: AustraliaPosts: 468 |
G'day Phenix, No problems but nothing too exiting to look at: PC3 / BT modules / FT232 ETC  Pump Test needs to be re-sized to suit on screen keyboard  Keyboards, upper is USB-Wireless, lower is Bluetooth (can be very confusing)  Teraterm as console, Realterm talking to FT232/HM10  The "experimenters bench" looks like a nuclear blast so no overall pics I'm afraid. The occasional ant is moving real fast from all the absorbed coffee  Regards, Lyle. |
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| PhenixRising Guru Joined: 07/11/2023 Location: United KingdomPosts: 2097 |
"a picture paints a thousand words" Looks great |
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| dddns Guru Joined: 20/09/2024 Location: GermanyPosts: 924 |
@ville56 Thanks again for your suggestions. I implemented all of them and it reduced the noise to a minimum which is absolutely ok now. |
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| ville56 Guru Joined: 08/06/2022 Location: AustriaPosts: 641 |
Peter, with PicoMitePC3 MMBasic USB RP2350B Edition V7.00.00RC1 I have a problem copying files from C: to A: drive. Not even a file with about 15kB is properly copied. For example c:c.jpg with 14726 bytes is copied to a: with 5120 bytes. As the copied part of the jpg can be displayed I assume the copy just stops after a few 1000 bytes. After the copy operation the drive c: is partially inaccessible and behaves strange. e.g.: > c: > files C:/ 14:44 15-10-2026 1440054 a.bmp 14:31 15-10-2026 215338 a.jpg 19:35 07-07-2026 14726 c.jpg 15:02 15-10-2026 0 d.jpg 0 directories, 4 files > kill "d.jpg" Error : A hard error occurred in the low level disk I/O layer > files C:/ 14:44 15-10-2026 1440054 a.bmp 14:31 15-10-2026 215338 a.jpg 19:35 07-07-2026 14726 c.jpg 0 directories, 3 files > so d.jpg is deleted but every access to a specific file (LOAD JPG) results in an error and takes a long time. I've tried this with an USB drive and a SD card with an USB adapter, both behave identical. Gerald 73 de OE1HGA, Gerald |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 12034 |
I would suspect your flash drive is corrupt or similar  |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 9220 |
Was your test carried out with a USB memory stick? Did it work on earlier versions? AFAIK SD card adapter sticks and USB drives don't work in quite the same way and I'm not sure if they are supported. USB on the Picomite is restricted compared to "full" OS systems. Mick Zilog Inside! nascom.info for Nascom & Gemini |
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| ville56 Guru Joined: 08/06/2022 Location: AustriaPosts: 641 |
I've tried it on both, stick and adapter, and they have the same issue. Have to dive deeper into that. And no, I didn' t try it on RC0 which is the only older version available. 73 de OE1HGA, Gerald |
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| dddns Guru Joined: 20/09/2024 Location: GermanyPosts: 924 |
I have transferred an MP3 file via tftp. This has the same size as the source according to files or fm. If I replay this file it has errors and jumps what you can hear. If I copy that file it fails or only copies fragments. It seems to be corrupt. Other files I copied with my PC to the stick are copied from C: to A: in a speed I have never seen like 500Kb/s |
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| ville56 Guru Joined: 08/06/2022 Location: AustriaPosts: 641 |
Peter, I have now flashed onto the PC3 PicoMiteHDMI MMBasic USB RP2350B Edition V7.00.00RC1 and that version works ok. The version with the issue is PicoMitePC3 MMBasic USB RP2350B Edition V7.00.00RC1 I hope I've not used the wrong version before ... Edit: seems to be a problem with pico flash artefacts!! After trying the PicoMiteHDMI version which worked, I reflashed PicoMitePC3 and now it magically also works. I've only changed the resolution to 1024 on both versions due to sync probs on my HDMI monitor, all other optons were left to default. The drive a: was also preserved and ok as was copying files from c: to a:. OK, so at least I know for the next time where to look first ...  . Maybe a flash nuke upfront would have avoided it.Edited 2026-10-16 00:27 by ville56 73 de OE1HGA, Gerald |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 12034 |
I was testing on the PC3 version. The other possibility is power supply. PC3 starts up the WIFI chip and HDMIUSB doesn't so if the power is marginal.... Edited 2026-10-16 00:27 by matherp |
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| ville56 Guru Joined: 08/06/2022 Location: AustriaPosts: 641 |
Yes, power could also be a source of troubles, thanks for that input. I will consider that as well next time. Note: I've tried the config now with Wifi, SD-card and USB-stick all at the same time but it is stable. So powersupply seems not to be a problem. Still blame it on the pico flash ... Edited 2026-10-16 01:27 by ville56 73 de OE1HGA, Gerald |
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homa Guru Joined: 05/11/2021 Location: GermanyPosts: 715 |
PicoMitePC3 RC1 – FRAMEBUFFER LAYER in MODE 3 fails Hi Peter, on the PC3 (PicoMitePC3 V7.00.00RC1, OPTION LIST below), directly at the prompt: NEW MODE 3 FRAMEBUFFER LAYER Error : Layer Buffer must be in tightly coupled RAM The manual lists HDMI mode 3 with automatic layer. Is the layer in mode 3 possible on the PC3 (PSRAM fitted), or is this a known limit? Matthias > option list PicoMitePC3 MMBasic USB RP2350B Edition V7.00.00RC1 OPTION SERIAL CONSOLE COM2,GP8,GP9 OPTION SYSTEM I2C GP20,GP21 OPTION FLASH SIZE 16777216 OPTION COLOURCODE ON OPTION KEYBOARD GR, 0, 1, 200, 75 OPTION HEARTBEAT OFF OPTION PICO OFF OPTION RESOLUTION 640x480 @ 315000KHz OPTION HDMI PINS 1, 3, 5, 7 OPTION WIFI behofam, *****************, Pico3, DE OPTION TELNET CONSOLE ON OPTION SDCARD GP33, GP30, GP31, GP28 OPTION KEYBOARD REPEAT 200,75 OPTION AUDIO I2S GP10,GP22', ON PWM CHANNEL 11 OPTION RTC AUTO ENABLE OPTION COUNT GP34,GP35,GP36,GP37 OPTION COMPILE ON OPTION PLATFORM PICO COMPUTER 3 OPTION PSRAM PIN GP47 > |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 12034 |
This is the limitation of having lots of memory tied up for bluetooth and web use. I'll update the manual to identify modes which won't be available on the PC3 build |
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| homa Guru Joined: 05/11/2021 Location: GermanyPosts: 715 |
Oh, that's really unfortunate. I like the layer principle and Mode 3. Do you see any chance of that happening in the future? At least one :) |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 9220 |
When Raspberry Pi make a new, upgraded model with more RAM to replace the RP2350n? Having "proper" fast RAM available is the thing. Everything is a compromise. Mick Zilog Inside! nascom.info for Nascom & Gemini |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 12034 |
Not on the rp2350B, it simply doesn't have enough memory and psram is too slow. The same effect can be simulated by using blit framebuffer. Or just use the HDMIUSB build if you don't need Web or Bluetooth |
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