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STM32F303 based 4 channel 5MS "oscilloscope"
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Miyuki:
Don't they already exist? Just for sure to not inventing wheel again

STM32F303 look like nice chip for small DIY but usable oscilloscope, have 4 decent ADC with 5MS per channel at 12bit and little faster at lower accuracy, also have memory controller to connect external SRAM

Is here any issue why they are not all over ebay ?
MosherIV:

--- Quote ---have 4 decent ADC with 5MS per channel at 12bit and little faster at lower accuracy, also have memory controller to connect external SRAM
--- End quote ---
The key part of that specification is 'per channel'
As far as I am aware, the ST32F series only have 1 (or 2 at most) ADC(s) per microcontroller
You can only acheive the max 5Million samples per sec on a single channel, after that you have to multiplex and the sample rate is shared accordingly.

Yes, you can couple the ADC to the DMA to the SDRAM controller but it also drops the transfer rate from the ADC to the DMA channel.


--- Quote ---Is here any issue why they are not all over ebay ?
--- End quote ---
There are cheaper microcontrollers eg the one used on Arduinos.
It would be easier to do the capture with FPGAs (see Analogue Discovery 2 and Redpitaya)
Just 2 off the top of my head.
Miyuki:

--- Quote ---As far as I am aware, the ST32F series only have 1 (or 2 at most) ADC(s) per microcontroller
You can only acheive the max 5Million samples per sec on a single channel, after that you have to multiplex and the sample rate is shared accordingly.

--- End quote ---
F303 have 4 separated ADC capable of 5MSPS at 12bit and 7.2 at 8 bit


--- Quote ---There are cheaper microcontrollers eg the one used on Arduinos.
It would be easier to do the capture with FPGAs (see Analogue Discovery 2 and Redpitaya)
Just 2 off the top of my head.

--- End quote ---
I don't know about any other cheap microcontroller with similar ADC capability
FPGA is nice, but not for "small" DIY project, and this boards cost like factory scope, so no reason to use them as scope
MosherIV:

--- Quote ---F303 have 4 separated ADC capable of 5MSPS at 12bit and 7.2 at 8 bit
--- End quote ---
OK, I did not know that.
However, as I said, once you have daisy chained the DMA and SD RAM controller, the data rate would not be sustainable.
Especially for 4 channels.


--- Quote ---I don't know about any other cheap microcontroller with similar ADC capability
--- End quote ---
No, I miss led you there. The Atmel devices do not have comparable ADCs but the criteria is cheapness !

http://www.ebay.co.uk/itm/Assembled-DSO138-2-4-Inch-TFT-Digital-Oscilloscope-1Msps-Probe-US-Plug-Power-/222582456820?var=&hash=item33d2f2c1f4:m:mY9_zw6EIvPgeIXn0icnISg
The processor is the 2nd most expensive part in that kit - so it has to be CHEAP !!

BTW 5Million samples per second sound like a lot but that only gives that only gives you a possible bandwidth of 2.5MHz
Not really enough for a decent oscilloscope.
JPortici:
dsPIC33EP GS series (like http://www.microchip.com/wwwproducts/en/dsPIC33EP64GS504) has 5 ADCs, 3.125 MSPS per ADC and it's around 11.8 ENOB :)
also PIC32MK/MZ, but it's not really "cheap" anymore (though you should compare them with cortex M7)

actually any decent manufacturer will have a line of cheap MCUs with multicore adcs, not everyone will have a good adc onboard
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