Raspberry Pi - New Microcontroller

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NormanDunbar
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Raspberry Pi - New Microcontroller

Postby NormanDunbar » Thu Jan 21, 2021 1:04 pm

This looks very interesting. I think you hardware types might like the Programmable I/O section of the data sheet. Similar to FPGA???

https://www.raspberrypi.org/blog/raspbe ... w-on-sale/

If you have a subscription to Hackspace magazine, you are getting a freebie. Good luck hitting the supermarkets/newsagents to get a copy otherwise!

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Peter
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Re: Raspberry Pi - New Microcontroller

Postby Peter » Thu Jan 21, 2021 3:11 pm

NormanDunbar wrote:I think you hardware types might like the Programmable I/O section of the data sheet. Similar to FPGA???

Except having two cores, it's a microcontroller like many others. Peripherals not too exciting, not even ADCs. Can't see any FPGA (or even PLD) like possibilities.
But thanks for the news!


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Re: Raspberry Pi - New Microcontroller

Postby NormanDunbar » Thu Jan 21, 2021 4:10 pm

Interesting!

The data sheets pin out has 5 pins for ADC - AGND, ADC_VREF and ADC0, ADC1 & ADC2.

I've yet to read the 800+ pages of the chip datasheet and the board datasheet, so I'll defer to your better knowlege.

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Re: Raspberry Pi - New Microcontroller

Postby tofro » Thu Jan 21, 2021 4:56 pm

Peter wrote:Except having two cores, it's a microcontroller like many others. Peripherals not too exciting, not even ADCs. Can't see any FPGA (or even PLD) like possibilities.


Well, the programmable PIO state machines are somewhat unique. Having 4 independent state machines running up to 32 instructions each independent from the main processor with access to arbitrary GPIO lines is a bit of CPLD-like and can relieve the main CPU quite a bit from bit-banging protocols. I'd guess thet for example implementing the QL network protocol might be quite a breeze on them.


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Re: Raspberry Pi - New Microcontroller

Postby martyn_hill » Thu Jan 21, 2021 7:32 pm

I was looking at this device earlier this afternoon with a view to how it might replace the Teensy uC around which the current QLUB Adapter is designed.

Aside from the 3.3V to 5V translation (easy enough) , the other important aspect I'm still researching is how the onboard USB port is implemented - one reason why the usual Arduino dev boards didn't quite cut-it for the QLUB was due to the inherent latency of the FTDI to USB interface used in those devices compared to the Teensy's inbuilt USB support.

I haven't quite waded through the RP2040 datasheet yet, but it looks like a potentially good (and cheaper) alternative...


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Re: Raspberry Pi - New Microcontroller

Postby NormanDunbar » Thu Jan 21, 2021 8:18 pm

Hi Peter,

Peter wrote:Peripherals not too exciting, not even ADCs.


There is indeed an onboard ADC. It'sbuilt in to the RP2040, has three channels and 12 bit resolution. There's a 4th channel used for the internal temperature sensor.

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Re: Raspberry Pi - New Microcontroller

Postby NormanDunbar » Thu Jan 21, 2021 8:20 pm

Hi Martyn,

martyn_hill wrote:I haven't quite waded through the RP2040 datasheet yet, but it looks like a potentially good (and cheaper) alternative...


Maybe the "coming soon" RP2040 Tiny willbe better? If not a little more expensive!

https://shop.pimoroni.com/products/tiny-2040

Cheers,
Norm.


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Re: Raspberry Pi - New Microcontroller

Postby Peter » Fri Jan 22, 2021 10:17 am

Hi Norman,
NormanDunbar wrote:There is indeed an onboard ADC. It'sbuilt in to the RP2040, has three channels and 12 bit resolution. There's a 4th channel used for the internal temperature sensor.

You are right of course. I was looking much too sloppy, and not directly into the data sheet. My apologies. Somewhere I read that a RP2040 based singleboard computer does not support ADC without external circuitry, but maybe that was board specific?
The programmable PIO state machines might indeed be sufficient to replace a PLD for specific, relatively slow purposes.
Also, there are boards for 4€, which is less than the microcontroller alone in many cases. For example, the AT90USB1286 used on the Teensy ++2.0 is about 7€ without the board.


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Re: Raspberry Pi - New Microcontroller

Postby NormanDunbar » Fri Jan 22, 2021 11:12 am

Hi Peter,

Peter wrote:Somewhere I read that a RP2040 based singleboard computer does not support ADC without external circuitry, but maybe that was board specific?


I'm not sure about that, sorry. The actual chip itself has the ADC on board. Maybe the board you were reading about doesn't bring the ADC connections out to headers?

Peter wrote:The programmable PIO state machines might indeed be sufficient to replace a PLD for specific, relatively slow purposes.


I think someone has used the PIO to provide two DVI outputs for the board. I am probably mistaken in that. Or maybe not! (For once!) https://github.com/Wren6991/picodvi from the engineer who did it.


Cheers,
Norm.


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Re: Raspberry Pi - New Microcontroller

Postby Peter » Fri Jan 22, 2021 11:35 am

Not mistaken, it took clever tricks, extreme overclocking, and spec violations to get there. ;) Compared to FPGA that seems a pain to implement, and would not be sufficient for Qzero-like resolutions. But still very impressive!

At first glance, I don't see where the RP2040 can be bought as a chip, do you have a link?



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