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Fw: [BITX20] RPi Pico -- Opps!


Jack, W8TEE
 

Opps...pressed the wrong key!


The Arduino flavor will have 16Mb of flash, according to:



which is why I first questioned the $4 price that was mentioned a number of posts ago.

Jack, W8TEE



On Thursday, January 21, 2021, 4:13:12 PM EST, Shirley Dulcey KE1L <mark@...> wrote:


The ones currently being made have 2MB of flash memory. The board will accommodate up to 16MB by substituting a larger flash memory chip, but no such boards are currently available and they will cost more than $4 when they appear. One unusual thing about the Raspberry Silicon is that it has no on-chip flash; code runs from memory in a separate flash chip, and it can do that without any speed reduction.

On Thu, Jan 21, 2021 at 12:56 PM Jerry Gaffke via groups.io <jgaffke=yahoo.com@groups.io> wrote:
Looks like we have a new mainstream microcontroller breakout board coming out.
At $4 it's nearly as cheap as a Nano, better build quality than an eBay blue pill.
https://www.raspberrypi.org/products/raspberry-pi-pico/
https://techcrunch.com/2021/01/21/raspberry-pi-foundation-launches-4-microcontroller-with-custom-chip/

Has dual ARM M0 cores at 133mhz, 264KB of RAM, "up to 16MB of flash" (I think it's off chip SPI flash), 
i2c, spi, digital IO, analog inputs, programmable in C and micropython, well documented.

Jerry, KE7ER


--
Jack, W8TEE


Jerry Gaffke
 

2MB of flash at $4 sounds fine to me, the Nano has 0.032MB.
RAM is likewise 100x larger on the RPi-pico.
But of course the ATMega328P processor on the Nano is nearly 30 yrs old,
so that's to be expected.  

Moving flash off chip makes for fewer process steps, and is thus considerably cheaper.
No idea how fast the RPi-pico Quad-SPI memory interface is, but here's a modern flash chip
that can transfer data at up to 160 MBytes/sec:  https://www.cypress.com/file/177986/download
I don't think the Arm M0 core includes instruction cache, though I assume you could execute
out of onboard RAM when you want fast.

Jerry, KE7ER


Rafael Diniz
 

If I can read well, the ADC pins of the RPi Pico are fewer and worse
precision - is that correct? I like my intel-based mini-itx talking to
the arduino over serial.
; )

Rafael

On 1/21/21 6:42 PM, Jerry Gaffke via groups.io wrote:
2MB of flash at $4 sounds fine to me, the Nano has 0.032MB.
RAM is likewise 100x larger on the RPi-pico.
But of course the ATMega328P processor on the Nano is nearly 30 yrs old,
so that's to be expected.  

Moving flash off chip makes for fewer process steps, and is thus
considerably cheaper.
No idea how fast the RPi-pico Quad-SPI memory interface is, but here's
a modern flash chip
that can transfer data at up to 160 MBytes/sec: 
https://www.cypress.com/file/177986/download
<https://www.cypress.com/file/177986/download>
I don't think the Arm M0 core includes instruction cache, though I
assume you could execute
out of onboard RAM when you want fast.

Jerry, KE7ER


Jerry Gaffke
 

Fewer and worse than what?

One 12bit ADC that can read from three different pins,  a forth channel to read chip temperature.
No real DAC.

Jerry, KE7ER


On Thu, Jan 21, 2021 at 01:46 PM, Rafael Diniz wrote:
If I can read well, the ADC pins of the RPi Pico are fewer and worse
precision - is that correct?


Rafael Diniz
 

Sorry, I did not specify, but I was thinking about a good arduino for
the comparison. I read the ADC is only 0 to 3.3V, and with limited
accuracy. No DAC is a miss also, so no way to do digital modes
"out-of-the-box".

Rafael

On 1/21/21 7:03 PM, Jerry Gaffke via groups.io wrote:
Fewer and worse than what?

One 12bit ADC that can read from three different pins,  a forth
channel to read chip temperature.
No real DAC.

Jerry, KE7ER

On Thu, Jan 21, 2021 at 01:46 PM, Rafael Diniz wrote:

If I can read well, the ADC pins of the RPi Pico are fewer and worse
precision - is that correct?


Jerry Gaffke
 

We were previously discussing the RPi-Zero, which for $5 has a much more
powerful ARM processor with far more RAM, instruction and data caches,
HDMI display, fast IO.

The RPi-pico fills a need though, as it would draw less power and has the ADC channels.
I think it will be popular for all the same reasons that the Nano remains so popular.
It's simple.

> I read the ADC is only 0 to 3.3V, and with limited
accuracy.

The ADC is 12bits, more than the Nano's 10bits, and as good as most other processor chips.
There are a very few processors that have 16bit ADC's on chip, or DAC's of any sort.
If you want a 16 bit ADC, it is probably better to have a separate chip,
away from all the digital noise of the processor.

And if you want 0 to 5v, then scale your input to 3.3v max with a couple resistors.
The only reason the Nano does 0 to 5v is because the chip used was designed in the early 1990's.

Jerry, KE7ER


Rafael Diniz
 

Tks Jerry - you are right. I just don't understand why one would want
more cpu and memory for a mcu which does only commands and control, no
dsp functions at all. OK - it could be for a nice and fancy UI...

Rafael

On 1/21/21 7:36 PM, Jerry Gaffke via groups.io wrote:
We were previously discussing the RPi-Zero, which for $5 has a much
more powerful ARM processor with far more RAM, instruction and data
caches, HDMI display, fast IO. The RPi-pico fills a need though, as it
would draw less power and has the ADC channels. I think it will be
popular for all the same reasons that the Nano remains so popular.
It's simple. > I read the ADC is only 0 to 3.3V, and with limited
accuracy. The ADC is 12bits, more than the Nano's 10bits, and as good
as most other processor chips.
There are a very few processors that have 16bit ADC's on chip, or
DAC's of any sort.
If you want a 16 bit ADC, it is probably better to have a separate chip,
away from all the digital noise of the processor.

And if you want 0 to 5v, then scale your input to 3.3v max with a
couple resistors.
The only reason the Nano does 0 to 5v is because the chip used was
designed in the early 1990's.

Jerry, KE7ER