Spark Logic

$10 O-Scope revisited

ahull

Over the last few days I’ve been playing with Ray’s STM32 Oscilloscope idea.

Image

Some preliminary results are available here..

https://github.com/pingumacpenguin/STM3 … ontruction

My take on the Scope Sketch is here..

https://github.com/pingumacpenguin/STM32-O-Scope

Its a fun little project and well worth building just for the entertainment value. Currently bandwidth is a little limited, but with a little extra effort it would be possible to make a fully functional 2MHz Scope for next to nothing. Ideal for probing i2c, audio and other low speed signals.

EDIT: We managed to squeeze the maximum speed out of the ADC, read further through the thread for details. The github code includes all of the enhancements made of the course of this thread.

Replies20

ahull Wed Mar 30, 2016 12:49 am

rexnanet wrote:rexnanet wrote:
With an overclocked ADC we must keep the 1.5clk on the sample time to allow a proper sampling of the signal.

mrburnette Wed Mar 30, 2016 1:19 pm

Could it be that the PIg-O-Scope has gone commercial?
Amazon here.

This kit uses ARM Cortex-M3 processor (STM32F103C8), and includes a 2.4-inch color TFT
Pig-O-Scope.jpg
Pig-O-Scope.jpg (153.69 KiB) Viewed 1724 times

rexnanet Wed Mar 30, 2016 3:57 pm

RogerClark wrote:You could modify the SPI DMA transfer to be non blocking, and to generate an interrupt when the transfer is complete, as this would allow the core of the cpu to go off and do other stuff while the spi transfer was happening.

But I dont suppose there is much that the cpu could do while waiting for the spi transfer to finish?

mrburnette Wed Mar 30, 2016 4:28 pm

ahull wrote:I’ve seen a few of sellers offering that scope, both assembled and as a kit. It looks like quite a fun toy, but I don’t know if it is open source/open hardware.
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rexnanet Thu Mar 31, 2016 10:01 am

mrburnette wrote:

Well, it certainly does not come with a case for the < $30 they are asking … so, it certainly is open enclosure :roll:

Ray

zoomx Fri Apr 01, 2016 9:26 am

ahull wrote:I’ve seen a few of sellers offering that scope, both assembled and as a kit. It looks like quite a fun toy, but I don’t know if it is open source/open hardware.

mrmonteith Fri Apr 01, 2016 12:45 pm

It’s kind of interesting about that DSO138. If I remember right the red version is made by the company that originated it. But there is a knock-off version that is black. Of course I didn’t know that until I got one of the black ones. But I will say that it didn’t work after I got it put together and contacted them and they sent me a new one. Of course I think they get this stuff dirt cheap so no skin off their backs. Okay. I found my email.

DSO138 kits from Sainsmart is counterfeit product. Please see http://www.jyetech.com/Products/LcdScope/e138.php. If you have any other questions please feel free to contact us.
Best regards,
JYE Tech Sales

RogerClark Sat Apr 02, 2016 2:09 am

I guess it could also be usable as a general purpose board with LCD display, but I’m not sure its especially good value, at $17

(Considering the cost of the components is probably less than $10.)

rexnanet Wed Apr 06, 2016 3:49 pm

Still working on getting a stable trigger but it’s improved (maybe a bit of hysteresis because of ADC noise).

Maybe I’ll make a small video of the improvements. I think it’s a bit faster overall.

The Adafruit modified ILI9341 library is really fast! 34ms for a fillscreen is really good = 36Mb SPI speed. I thought SPI could only get to 18Mb using “normal” settings. Maybe somewhere there’s a DIV1 setting for the SPI module clock…?

RogerClark Wed Apr 06, 2016 8:38 pm

processor clock is 72mhz, so DIV2 is 36mhz

High speeds are helped by use of DMA

rexnanet Thu Apr 07, 2016 1:35 pm

RogerClark wrote:processor clock is 72mhz, so DIV2 is 36mhz

High speeds are helped by use of DMA

RogerClark Thu Apr 07, 2016 9:03 pm

LOL

I just read the spec..

It looks like we overclock the SPI, to twice its maximum speed.

No one has had any problems with this ;-)

mrburnette Thu Apr 07, 2016 9:10 pm

RogerClark wrote:
<…>
It looks like we overclock the SPI, to twice its maximum speed. No one has had any problems with this ;-)

RogerClark Thu Apr 07, 2016 9:20 pm

Hi have several systems I built for my extended family that use Maple mini and the ili9341 display, that have litterally been running non stop for months ( at least 9 months), without any problems at all.

I dont think there is any need to change the core to reduce the speed even if we are overclocking.

But perhaps I should add a readme in the SPI library just so everyone is aware that we deliberatly overclock

mrburnette Thu Apr 07, 2016 9:22 pm

RogerClark wrote:
<…>
But perhaps I should add a readme in the SPI library just so everyone is aware that we deliberatly overclock

RogerClark Thu Apr 07, 2016 9:29 pm

Live’s no fun unless you overclock, sometimes.

rexnanet Fri Apr 08, 2016 9:11 am

mrburnette wrote:RogerClark wrote:
<…>
But perhaps I should add a readme in the SPI library just so everyone is aware that we deliberatly overclock

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