DLO-138 OScope

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rexnanet
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Re: DLO-138 OScope

Post by rexnanet » Wed Mar 01, 2017 10:48 am

From what I saw on DSO-138 firmware, the sampling code is hidden in a pre-compiled lib so I don't know how they sample the signals.
But on DLO-138 I still haven't checked that, is it the same block as on DSO-138?

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ThunderOwl
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Re: DLO-138 OScope

Post by ThunderOwl » Wed Mar 01, 2017 10:53 am

I am asking, because, from what I read around, DSO-138 is barely usable up to 100kHz (I don't have DSO-138).
Would be very informative to post some screenshots of square wave at different frequencies of new version(s).
In every man's childhood, first 40 years are the hardest

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rexnanet
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Re: DLO-138 OScope

Post by rexnanet » Wed Mar 01, 2017 10:57 am

But the sampling rate should be 1MSPS, I think.

The limitation as I recall is on the analog frontend. I don't thing the input approach is the best for this...

mausi_mick
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Re: DLO-138 OScope

Post by mausi_mick » Wed Mar 01, 2017 11:02 am

excuse me,

is that ok (in dlo-138 : display) line 174:

// ------------------------
void clearNDrawSignals() {
// ------------------------
static boolean wavesOld[4] = {false,}; <<< ???????
static int16_t yCursorsOld[4];

mausi_mick
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Re: DLO-138 OScope

Post by mausi_mick » Wed Mar 01, 2017 11:07 am

and here my code (DLO-138, ILI9341 SPI, AD9851 with Touch)
DLO-138-02.7z
(14.75 KiB) Downloaded 53 times

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rexnanet
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Re: DLO-138 OScope

Post by rexnanet » Wed Mar 01, 2017 11:46 am

mausi_mick wrote:excuse me,

is that ok (in dlo-138 : display) line 174:

// ------------------------
void clearNDrawSignals() {
// ------------------------
static boolean wavesOld[4] = {false,}; <<< ???????
static int16_t yCursorsOld[4];
That should issue at least a compiler warning IMO.
I would add the remaining values just to be sure...

P.S. Thanks for the code!

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ThunderOwl
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Re: DLO-138 OScope

Post by ThunderOwl » Wed Mar 01, 2017 1:36 pm

Thanks a lot, mausi_mick !
In every man's childhood, first 40 years are the hardest

willfly1
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Re: DLO-138 OScope

Post by willfly1 » Wed Mar 01, 2017 4:16 pm

mausi_mick wrote:excuse me,

is that ok (in dlo-138 : display) line 174:

// ------------------------
void clearNDrawSignals() {
// ------------------------
static boolean wavesOld[4] = {false,}; <<< ???????
static int16_t yCursorsOld[4];

Code: Select all

static boolean wavesOld[4] = {false,};
Yes, it is allowed in C++ array initialization syntax.

On another question about bandwidth, IMO these low sampling ADC's are good for viewing audio level signals, which is what most hobbyist's need. Anything above hundred Khz is probably in digital - logic analyzer domain.

willfly1
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Location: GTA, Canada

Re: DLO-138 OScope

Post by willfly1 » Wed Mar 01, 2017 4:37 pm

rexnanet wrote:From what I saw on DSO-138 firmware, the sampling code is hidden in a pre-compiled lib so I don't know how they sample the signals.
But on DLO-138 I still haven't checked that, is it the same block as on DSO-138?
No, I didn't use their sampling library. Due to the addition of second analog channel, DLO lowest timebase (20 uS/div) is slower then DSO timebase (10 uS/div). F103 ADC's can be operated in interleaved mode with DMA, resulting in 0.58 uS/sample for 72 MHz clock. In DLO they operate in synchronous mode and yield 1.17 uS/sample.

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ThunderOwl
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Re: DLO-138 OScope

Post by ThunderOwl » Wed Mar 01, 2017 5:55 pm

willfly1 wrote: On another question about bandwidth, IMO these low sampling ADC's are good for viewing audio level signals, which is what most hobbyist's need. Anything above hundred Khz is probably in digital - logic analyzer domain.
For just look at signal at low frequencies it will do the job, but what if that low frequency signal has some short spikes (probably ones you want to fix in some device, say, PSU PWMs) - spikes will not be displayed, they will not even be captured, they will be somewhere between ADC sampling points.
In every man's childhood, first 40 years are the hardest

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