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Forum Index : Microcontroller and PC projects : Eureka
| Author | Message | ||||
| matherp Guru  Joined: 11/12/2012 Location: United KingdomPosts: 9284 |
 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 Senior Member  Joined: 01/10/2023 Location: UkrainePosts: 293 |
 This is another small step towards the widespread use of PSRAM on PicoMite  |
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| javavi Senior Member Joined: 01/10/2023 Location: UkrainePosts: 293 |
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: 3163 |
Exactly which PCB is this? PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| javavi Senior Member Joined: 01/10/2023 Location: UkrainePosts: 293 |
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 Senior Member Joined: 01/10/2023 Location: UkrainePosts: 293 |
@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: 9284 |
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: 917 |
I love those eureka moments   |
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| dddns Newbie  Joined: 20/09/2024 Location: GermanyPosts: 21 |
I would like to use a Pimoroni PGA2350 as a base. Is it (fully) supported by Picomite? Good idea? |
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| javavi Senior Member Joined: 01/10/2023 Location: UkrainePosts: 293 |
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: 9284 |
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 Senior Member Joined: 01/10/2023 Location: UkrainePosts: 293 |
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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