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Forum Index : Microcontroller and PC projects : WeAct board with RP2350B won't boot
| Author | Message | ||||
| v.lenzer Senior Member  Joined: 04/05/2024 Location: GermanyPosts: 140 |
I have a WeAct board with an RP2350B. I soldered a PSRAM chip onto the board, which is addressed via GP47. Previously, MMBasic V6.03.00 was installed, and I was able to run programs on it. Now I want to flash V6.03.01, but I haven't succeeded because the board won't boot. I’ve already tried all the tips found online (press and hold BOOT, connect USB-C, press RESET, release RESET, release BOOT). However, the board does not appear as a drive on my PC. I can rule out the cable as the source of the problem, as I successfully used it to flash other identical boards. The board that won't flash still connects to the terminal without issues, so it isn't defective. I can also rule out the PC, since I was able to flash all the other WeAct RP2350B boards using it. The only difference is that one board has PSRAM connected to GP0, while the others have no PSRAM. Does anyone have any advice on how I can still flash this board? Best wishes! Joachim |
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| matherp Guru  Joined: 11/12/2012 Location: United KingdomPosts: 11721 |
Either they have wired it wrong or you have soldered it wrong. The PSRAM chip shares the QMI bus with the main flash chip. If QMI is compromised then it won't boot |
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| JanVolk Guru Joined: 28/01/2023 Location: NetherlandsPosts: 395 |
Joachim, I have a board like that and have mounted PSRAM on it. It works fine with V6.03.00 and GP0 = PSRAM. However, the CS operates via GP0, and I notice you’ve switched to GP47? I don't have any experience with that yet, but I do plan to try it out using a separate wire connected to GP47. The schematic shows the CS connected to GP0 via R14 (0Ω), so my plan was to locate and remove R14 and attach a separate wire instead. The pull-up resistor R13 (10kΩ) is in the right place, and there is still room for a capacitor next to the PSRAM. I imagine pin 1 (CS) of the PSRAM could be connected directly to GP47 using a short wire? Jan. |
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| v.lenzer Senior Member Joined: 04/05/2024 Location: GermanyPosts: 140 |
Hi Jan! I simply bent Pin 1 of the PSRAM upwards and soldered a short wire to it. I connected the other end to GP47. I haven't soldered in the capacitor (yet). Unfortunately, the resistor markings on the board are illegible even under a microscope, so I couldn't locate a jumper (0-ohm resistor). However, I did measure a direct connection between GP0 and Pin 1 of the footprint. Since the pin on the PSRAM is bent up, though, it should work if you just connect Pin 1 to GP47. I hope we're talking about the same board. Mine is this one:  Best wishes! Joachim |
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| JanVolk Guru Joined: 28/01/2023 Location: NetherlandsPosts: 395 |
Joachim, That’s where the problem lies. If you disconnect pin 1 from the board, the CS pin floats because the pull-up is no longer connected. Leave pin 1 connected to the board, locate resistor R14 (0Ω), remove it, and install just the wire instead. Jan. |
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| v.lenzer Senior Member Joined: 04/05/2024 Location: GermanyPosts: 140 |
Peter, you're right. I removed the connection to GP47 and connected the PSRAM's CS to GP0. Now the RP2350B boots up again. Thanks for the tip. @Jan: Thanks for your offer to test a change to the CS. That won't be necessary now. PS: Hi Jan, our posts crossed. Edited 2026-08-07 08:58 by v.lenzer Best wishes! Joachim |
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| JanVolk Guru Joined: 28/01/2023 Location: NetherlandsPosts: 395 |
v.lenzer, https://github.com/WeActStudio/WeActStudio.RP2350BCoreBoard/blob/main/HDK/RP2350B_SCH.pdf Jan. |
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| AlbertR Senior Member Joined: 29/05/2025 Location: GermanyPosts: 108 |
v.lenzer I had identified it using the DMM  I wasn't sure if it would work because of the length of the wire.  But so far, everything seems to be working fine, even at 378 MHz. Is there perhaps a program I can use to test it that puts a bit of a load on the memory? Albert |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 9012 |
TBH I can't understand the thinking behind using GP47 for PSRAM CS. One of the big advantages of the RP2350 is having 8 ADC inputs accessible rather than 3/4 so it seems silly to throw one away. There are other choices for UART0 if that's the issue. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| v.lenzer Senior Member Joined: 04/05/2024 Location: GermanyPosts: 140 |
Hi Albert! Simply type "Memory" into the console. It will then show you 6 MB of RAM. You should also be able to flash MMBasic using this method. I assume you removed R14, right? Hi Mick! You make a valid point. When I first started out here, I built a few circuits using the RP2040-Zero—some of them involving I2C. For those, I used GP0 and GP1 as the I2C interface. Recently, I put together another board and wanted to reuse my previous circuit designs. Since switching to GP47 for CS during the PSRAM installation looked easy, I gave it a try. Unfortunately, that led to the issues I already described ;). Also—silly as it sounds—GP47 was simply the pin left over in my layout. Hi Peter! Does the rule still stand that camera data pins above 32 cannot be used with V.6.03.01? If so, I’ll revise the layout for my motion detector. I’ve already ordered the OV5640 :) Best wishes! Joachim |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 11721 |
For performance reasons the GPIO used for the camera data pins cannot straddle gp31/gp32 on the rp2350. You can use any set of 8 below or above the boundary |
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