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Forum Index : Microcontroller and PC projects : Eureka
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| matherp Guru  Joined: 11/12/2012 Location: United KingdomPosts: 10067 |
 Transpires there is a bug in the sdk that resets the PSRAM timings when you write to flash. I've put in some code to restore them after flash writes and now the Pimoroni Plus can run at 372 or 378MHz allowing widescreen HDMI. Also tested on PGA2350 Edited 2024-12-22 00:16 by matherp |
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javavi Guru Joined: 01/10/2023 Location: UkrainePosts: 436 |
 This is another small step towards the widespread use of PSRAM on PicoMite  |
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| javavi Guru Joined: 01/10/2023 Location: UkrainePosts: 436 |
Wouldn't it be nice to write some kind of stress test to check the used memory of PSRAM? I did a simple test of the speed of copying one 1kB template array to arrays occupying the rest of the space, and this test paradoxically showed the same speed on both PicoMite without PSRAM and with it. |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3310 |
Exactly which PCB is this? PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| javavi Guru Joined: 01/10/2023 Location: UkrainePosts: 436 |
For example, in my experiments with PSRAM I use a Chinese clone of Pico2 called RP2350-Plus to which I soldered the PSRAM chip on top of the flash memory chip. To select the PSRAM chip, one port of Pico2 is used, in my case it is GP8.   Edited 2024-12-22 11:03 by javavi |
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| javavi Guru Joined: 01/10/2023 Location: UkrainePosts: 436 |
@matherp Regarding the PSRAM with PicoMite RP2350, I would also like to understand how this extended RAM memory is distributed in the PicoMite memory system, as well as how and where the built-in SRAM memory of the RP2350 chip is used when the PSRAM is connected? |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10067 |
PSRAM is allocated to the MMBasic heap used for arrays, strings etc. built-in RAM is used preferentially until full unless the request is too big in which case PSRAM is used |
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| PhenixRising Guru Joined: 07/11/2023 Location: United KingdomPosts: 1142 |
I love those eureka moments   |
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| dddns Senior Member  Joined: 20/09/2024 Location: GermanyPosts: 261 |
I would like to use a Pimoroni PGA2350 as a base. Is it (fully) supported by Picomite? Good idea? |
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| javavi Guru Joined: 01/10/2023 Location: UkrainePosts: 436 |
My testing of memory block array write/read/copy speeds showed little difference in speed between the built-in SRAM and external PSRAM memory. Tested with different block sizes from 1KB to 32KB. MEM BLOCK: 1k 2k 16k ------------------------------------------- SRAM WR - 1.81 mS 3.55 mS 28.10 mS SRAM RD - 1.80 mS 3.53 mS 27.90 mS SRAM CP - 2.61 mS 5.17 mS 40.91 mS ------------------------------------------- PSRAM WR - 1.99 mS 3.85 mS 30.30 mS PSRAM RD - 1.96 mS 3.81 mS 29.40 mS PSRAM CP - 2.75 ms 5.40 mS 43.83 mS |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10067 |
More info - not good though It now appears that the tuning of the timing is probably dependent on the specific RAM chip used. I'm tuning based on the ram used by Pimoroni but it may not suit other RAM variants. I can just get the 372MHz required for 1280P HDMI video but can't reliably get 378MHz. Sometimes it boots and sometimes it doesn't so I'm limiting the clock speed to 372MHz for standard PicoMite and 315000 for PicoMiteVGA The question doesn't really mean anything. Currently there is no official PicoMite release for the RP2350 but there will be very soon. What versions are you intending to use and for what? Are you aware that you can't buy RP2350 chips - only built modules? |
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| javavi Guru Joined: 01/10/2023 Location: UkrainePosts: 436 |
What PSRAM memory chip do you use? I have this ESP-PSRAM64H 133MHz 3.3V I can check your firmware version for myself! |
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| PhenixRising Guru Joined: 07/11/2023 Location: United KingdomPosts: 1142 |
This one. I'll test mine tomorrow Edited 2024-12-23 03:06 by PhenixRising |
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| dddns Senior Member Joined: 20/09/2024 Location: GermanyPosts: 261 |
yes, exactly this one as it has all pins lined out even the bootsel. My question was more or less, if it runs stable. Now I have seen in older discussions, that it not possible to overclock it to values required for VGA or HDMI..Can anyone confirm? |
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| dddns Senior Member Joined: 20/09/2024 Location: GermanyPosts: 261 |
@Javavi The board that carries the RP2350 looks nice. What is this..got a link? |
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| javavi Guru Joined: 01/10/2023 Location: UkrainePosts: 436 |
This board is the so-called Murmulator 2.0 The second version, unlike the first versions of Murmulators, is still in the development stage. The purpose of redesigning the circuit was to create a Pico2 on the RP2350A with HDMI support. PicoMite HDMI works great on this board, including PWM sound, PS/2 keyboard and mouse, SD card, and it is also possible to connect an external USB Hub. Murmulator boards are an inexpensive solution for credit card-sized development boards for creating retro console emulators on the RPi Pico. There are many emulator firmwares, but only for Murmulator 1.x. For Murmulator 2.0, I think there is only ZX-Spectrum at the moment, but this is just the beginning of the promotion. I don’t know if it is permissible to open a topic on this board here on the forum? If you are interested, write me a personal message. |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3310 |
Anyone can open a microprocessor topic in this "Microcontrollers and PC projects" forum--no restriction on which microprocessor. Obviously, microprocessors which run MMBasic get most of the coverage. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9486 |
Can we all ASSUME that RP will be selling just the 2350 chips at some point, as they do now with the 2040? Can I ASSUME that you can only buy modules at the moment, as stocks of the new 2350 chips are not huge, so RP are only selling them to companies making modules that use them, yes? I also recall there being a silicon error on the new chips. Nothing drastic, but perhaps they are fixing that before selling discrete chips to people? I've had a bit of a hunt around on the RP website and forum, but cannot find any mention of this aspect of things. Peter - you do a lot of work with these chips - do you have any information on that? Wondering if an in-house all-in-one board similar to the CMM1.5 currently available, where the 2040 chip is directly mounted to the PCB design, therefore not requiring you to use 3rd-party modules. I always prefer the all-in-one designs, as they just look neater and more tidy then designs having plug-in modules. Speaking as someone who has designed boards where you plug in modules etc myself, but I don't love the concept that much! However, this is more of a personal preference of mine, more then for any kind of functional reasons. Smoke makes things work. When the smoke gets out, it stops! |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10067 |
The latest on the Pi forums suggests no chips before end quarter 1 at the earliest |
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| javavi Guru Joined: 01/10/2023 Location: UkrainePosts: 436 |
What chip are you talking about? I just looked, RP2350A chips are sold for ~5$ on AliExpress |
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