Chart shift mode

General discussion
1

Hi,

I’m wondering how efficient the Chart’s shift mode (LV_CHART_UPDATE_MODE_SHIFT) is. I’ve created identical graphs using a Chart widget and a line widget. I compared their speeds and found the graph I made using the line widget slightly faster. I used shift mode for the Chart graph. Is this expected, or could I have incorrectly set up the shift mode?

Thanks!

2

Hi,

Exactly where did you measure performance difference? In rendering or adding new data?

3

Hi,

I’m measuring the draw time (refr_invalid_areas). The graph I created is just a sine wave that shifts to the left.

Many thanks

4

It’s interesting. Could you send some code snippets (about the built-in chart usage and custom solution too) so that I can examine what happens?

5

Hi,

Apologies for the late reply, I did not have access to the code until today.

This is the graph made from the Chart widget:

image
image746×290 20 KB

I’m updating it using lv_chart_set_next_value()

This is the graph made from the Line widget:
image
I’m updating it by inserting values into an array and then setting them using lv_line_set_points() like this:

image
image1035×175 13.8 KB

image

Many thanks

6

Thank you! And how did you measure the performance?

7

I toggled a gpio pin high before refr_invalid_areas and low after it. Then I measured the time using an oscilloscope. Thanks!

8

I have any idea about what could be the difference.

Please comment out these two lines:

Please also check if the chart runs in crowded or normal mode.

9

I will give this a try when I get the chance. Many thanks for your reply.