DLO-138 OScope

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).

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…

excuse me,

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

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

and here my code (DLO-138, ILI9341 SPI, AD9851 with Touch)

(14.75 KiB) Downloaded 200 times

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];

Thanks a lot, mausi_mick !

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];

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?

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.

I have changed the Code for the SPI Display:
Now You can change betweeen functions/labels and the steps/parameters with the rotary encoder. The button of the encoder is only for changing between functions and steps.

But I haveto reduce the storage from 2048 to 1024 steps (because of AD9581/Touch?), I think the trigger is not perfect, perhaps I have to change the levels.
And by long timeBases ( >= 10mS) is a problem with the encoder / switches. On “10$ O-scope” I can do the parameter-changes inside the interrupt-routine inclusive update the small areas on the display.

on Youtube:

https://www.youtube.com/watch?v=aNsIR4r6Sw8

I quite fancy building one of these, I can think of a lot of uses I’d get out of it.

also with the label/function-selection is not very intuitive, therefore I tested touchscreen for the fields timebase, trigger, waves, wimndows etc.
Only with the cursors on the left and right side I have problems.

I Changed the on the top of the display the wave-field (A1,A2,D1,D2) more to the right and moved the window-field for the storage of the waves to the left.
Also I split the wave field in four separate fields. Now I can activate / deactivate each channel separate. And I changed the colour of the trigger-edge to orange for falling ( It was difficult to differentiate between them at least for my eyes …)

Now I need the button of the encoder only to start/activate the touch-function.

DLO138-SPI_Change_Labels_Touch.JPG (56.58 KiB) Viewed 897 times

now I have solved the problem with the cursor activating by touch:

on the left are the hidden touch-sensorfields for cursor 1…4 for the input signals,

x < 70
y > 60 and y <100: L_vPos1
y > 100 and < 130: L_vPos2
y> 130 and < 160: L_vPos3
y> 160 and < 190: L_vPos4

on the right is the field for the triggerlevel.

X> 280 and < 319
Y>100 and < 200: L_triggerLevel

and the source:

(15.49 KiB) Downloaded 132 times

Great work!

As for the trigger: Do you have the external circuit assembled? Or did you change the trigger method?
Because the original schematic has an external op-amp that receives a PWM to set the value and compares it with the input signal and sends the output to a pin that is used to start?/set? the trigger.

There are a bit of artifacts indeed… but might get solved

I might get a chance to try it out this weekend cause it seems that it will be rainy all weekend long…

now on youtube:

https://youtu.be/M8DlqzZ3ROI

Thanks Rexnanet,

yes there is VGEN (on PA10 in my SW)for maple-mini, but it’s open.
and TRIGGER_IN ( PA11 maple_mini).

I have to study the HW / schematic !!

You’re welcome

PB8 is TL_PWM, generates the voltage level for the comparator.
PA8 it TRIGGER, receives the logic signal from the comparator.

The chip is labeled U2D. And the other input of the comparator is ADCIN PA0.

Hope it makes it easier for you

there are some pins connected to hardware:

DSO MAPLE
AN_CH1 PA0 PB0
AN_CH2 PA4 PA0 ( problem with spi1 CS=PA4 ???)
TRIGGER_IN PA8 PA11
TRIGGER_LEVEL PA8 PB8
VSENSSEL1 PA2 PA2
VSENSSEL2 PA1 PA1
CPLSEL PA3 PA3
VGEN PB9 PA10
TL_PWM PB8 ????

VGEN I can’t see in the schematic
I haven’t found TL_PWM in the original-software DLO-138 (global.h)

mausi_mick wrote:there are some pins connected to hardware:

DSO MAPLE
AN_CH1 PA0 PB0
AN_CH2 PA4 PA0 ( problem with spi1 CS=PA4 ???)
TRIGGER_IN PA8 PA11
TRIGGER_LEVEL PA8 PB8
VSENSSEL1 PA2 PA2
VSENSSEL2 PA1 PA1
CPLSEL PA3 PA3
VGEN PB9 PA10
TL_PWM PB8 ????

VGEN I can’t see in the schematic
I haven’t found TL_PWM in the original-software DLO-138 (global.h)

mausi_mick wrote:now on youtube:
https://youtu.be/M8DlqzZ3ROI