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Forum Index : Microcontroller and PC projects : Pimoroni Pico Plus 2 W

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PhenixRising
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Joined: 07/11/2023
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Posted: 08:49am 27 Sep 2024
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Here we go again


Uses I2C? Does that mean no RX buffer?
Edited 2024-09-27 19:05 by PhenixRising
 
Mixtel90

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Posted: 09:08am 27 Sep 2024
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TBH I wouldn't risk it. The official version probably won't be that far off now and it'll have proper support and documentation (probably!).

I do wish the official Pico 2 had more flash though. I might be able to have some flash slots back then. :)

I2C for what?
.
Edited 2024-09-27 19:14 by Mixtel90
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs
 
PhenixRising
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Posted: 09:42am 27 Sep 2024
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  Mixtel90 said  TBH I wouldn't risk it. The official version probably won't be that far off now and it'll have proper support and documentation (probably!).

I do wish the official Pico 2 had more flash though. I might be able to have some flash slots back then. :)

I2C for what?
.


The "Raspberry Pi RM2 radio module" is I2C and Tom's Hardware believes that the official version will use the same module; "early release"

And why can't we buy the Raspberry Pi RM2 radio module for our existing Pico Plus-2s that we already received.

Edit: Maybe the Raspberry Pi RM2 radio module has buffer memory(?)
Edited 2024-09-27 19:44 by PhenixRising
 
PhenixRising
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Posted: 10:19am 27 Sep 2024
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Good ol' ChatGPT

  Quote  
The Raspberry Pi RM2 radio module, which features I2C communication, does not appear to have dedicated buffer memory for transmit and receive operations. The module likely relies on the I2C protocol's standard buffer sizes, which are typically constrained by hardware limitations (such as 32 bytes for many I2C devices). This can limit the amount of data transmitted or received in one operation. You may need to manage data buffering in software depending on the specific use case​(Tom's Hardware).
 
Mixtel90

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Posted: 11:24am 27 Sep 2024
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That makes sense. I2C was always intended for short messages and commands between devices on the same PCB. It's not designed for streaming as it's a multi-master system and another device may want the bus. It seems a bit odd to use it for wi-fi, but it's simple and cheap to implement. You just have to make your protocol solid enough and do your own buffering.
Mick

Zilog Inside! nascom.info for Nascom & Gemini
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PhenixRising
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Posted: 11:33am 27 Sep 2024
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Hi Mick,

It's the Bluetooth that I'm more concerned with because it's my link to the Android HMI. None of the comm's are urgent but they don't wanna be missed.

Think I'll go ESP32 if I need both WiFi and BT or at least stick with the HC-05.
 
Mixtel90

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Posted: 02:01pm 27 Sep 2024
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I don't know how the RPi bit works, but I assume it's sensible. Keep to short strings. You can still work just as you would with anything else.

If you are reading the bluetooth side directly make your program interrupt driven as a I2C slave produces an interrupt when there is a character to read. It's triggered on the first character.

Was the bluetooth side ever enabled for the Pico W? I'm not sure.
Edited 2024-09-28 00:04 by Mixtel90
Mick

Zilog Inside! nascom.info for Nascom & Gemini
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lew247

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Joined: 23/12/2015
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Posted: 09:02am 30 Sep 2024
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Just to confirm email from  <support@pimoroni.com>

  Quote  Hi Lewis,

Yes, all current RP2350 chips are affected by this issue. Raspberry Pi haven't announced if there will be any chip revisions yet.

Kind regards,
Hel

Edited 2024-09-30 19:03 by lew247
 
Mixtel90

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Posted: 10:43am 30 Sep 2024
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I'm not sure what the problem is with the Plus 2 and the PGA2350, but I suspect Pimorini have cheapened something or not followed the spec. Neither of them will overclock as well as the Pico 2.

If you assume that RPi will *ever* revise the RP2350 you may have to wait an extremely long time, possibly forever. Unless there is a demand *from large industrial users* they won't consider it as it's not economically feasible IMHO.

Just wait for the next new version. :)

(Just got a ESP8266-01S working on a Gamma board. I have a router connection on a Pico 2. :) )

.
Edited 2024-09-30 20:47 by Mixtel90
Mick

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Volhout
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Posted: 11:02am 30 Sep 2024
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Mick,

I am convinced the PSRAM equiped modules can not overclock as well because of physical limitations. I mean: because there are 2 memory devices on the QSPI bus. 2 devices, and the additional board traces, mean there is more capacitance on that bus.
More capacitance = more delay = lower frequency.

It is amazing that these PSRAM equipped devices can achieve 315MHz CPU clock.

Regards

Volhout
PicomiteVGA PETSCII ROBOTS
 
PhenixRising
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Posted: 12:56pm 30 Sep 2024
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  Mixtel90 said  I don't know how the RPi bit works, but I assume it's sensible. Keep to short strings. You can still work just as you would with anything else.

If you are reading the bluetooth side directly make your program interrupt driven as a I2C slave produces an interrupt when there is a character to read. It's triggered on the first character.

Was the bluetooth side ever enabled for the Pico W? I'm not sure.


No, the BT of the Pico W was never enabled.

The ESP32 makes sense because it's an independent MCU. I have created apps in B4A (Basic for Android) and B4R (Basic for Arduino) uses the same Basic syntax and also works for the ESP32. I'm sure I can tolerate the Arduino IDE for what I need.

Thus far, I have downloaded the Arduino IDE, something like 5 times and within minutes, uninstalled it Need to have a serious go  
 
Mixtel90

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Posted: 01:41pm 30 Sep 2024
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I got rid of that shambles. I won't install it on this machine again as it's a disk and RAM hog. I can't afford the resources to run it. I'd rather load something like ESP Basic than use that.
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs
 
Sasquatch

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Joined: 08/05/2020
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Posted: 04:27pm 30 Sep 2024
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  @Volhout said  I am convinced the PSRAM equiped modules can not overclock as well because of physical limitations. I mean: because there are 2 memory devices on the QSPI bus. 2 devices, and the additional board traces, mean there is more capacitance on that bus.
More capacitance = more delay = lower frequency.


I haven't completely given up on this!  My testing showed that the Pimoroni Pico2 Plus device worked at higher clock rates with the PSRAM removed, but the PGA2350 device wouldn't work above 315MHz even with the PSRAM removed.  This suggests to my mind that the PSRAM "loading" may only contribute to the problem.

The other thing both devices have in common is that the FLASH and PSRAM are mounted on the opposite side of the PCB from the RP2350B.  Each via looks to me like two 90 degree angles for the signal to navigate, generally not desirable for high speed signals.

When the RP2350 chips become available, we will need to do some testing with careful layouts to see if it's possible to have both the FLASH and PSRAM working at the higher clock rates.  Fortunately at JLCPCB prototyping prices it's a cheap education!
-Carl
 
matherp
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Joined: 11/12/2012
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Posted: 05:09pm 30 Sep 2024
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For info:
I've played with every conceivable parameter on the PGA2350 to try and up the speed.
This includes:
Changing the drive power on the 6 QSPI pins (2, 4, 8, 16mA)
Enabling/disabling Fast slew
Enabling/disabling Schmidt inputs
Changing CS delays before and after chip access
Changing the clock divider
Upping the core voltage (to 1.5V)
etc.


They all make a difference in some way (normally making it worse) buy nothing allows me to clock much above 315MHz. Even the 324MHz needed for the new XGA video modes is not workable.

Once the chip become available I will lay out a board with the RP2350B, 16Mb flash and 8Mb PSRAM with a variable linear regulator for the core voltage (default 1.1V) and we can see what happens. In the meantime the Pimoroni boards cannot be used above 315MHz so are probably best avoided.

Its also worth noting that I can clock the standard Pico2 well above 400MHz but in all cases flash write access fails once the speed is above about 396MHz. This happens irrespective of the QSPI clock divider. Read access is fine but without write the PicoMite firmware can't run.
 
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