Excessive dynamic memory useage

Projects Programming
1

Hi,
Can someone tell me please why this simple sketch uses 75% of dynamic memory as global
variables? - and how I can reduce this?

#include <Arduino.h>
#include <U8g2lib.h>
float AverageA = 0;
float beep;
float Beep_period;

U8G2_ST7567_JLX12864_F_4W_SW_SPI u8g2(U8G2_R3, /* clock=/ 7, / data=/ 8, / cs=/ 11, / dc=/ 9, / reset=*/ 10);
int inputPin = A0;

void setup(void) {
u8g2.begin();
u8g2.setContrast(80);
}

void loop(void) {
u8g2.clearBuffer(); // clear the internal memory
AverageA = (analogRead(A0) / 45.0) - 10.0;
u8g2.setFont(u8g2_font_timB24_tn);
if ((AverageA) >= 0) {
u8g2.setCursor(23, 28);
}
else {
u8g2.setCursor(12, 28); //move average display over to accomodate - sign
}
u8g2.print(AverageA);
u8g2.drawBox(0, 62, 17, 5); //divide line
//up triangles ********************
if ((AverageA) > 0.25) {
u8g2.drawTriangle(9, 50, 0, 61, 17, 61);
}
if ((AverageA) > 0.85) {
u8g2.drawTriangle(9, 44, 0, 55, 17, 55);
}
if ((AverageA) > 1.45) {
u8g2.drawTriangle(9, 38, 0, 49, 17, 49);
}
if ((AverageA) > 2.05) {
u8g2.drawTriangle(9, 32, 0, 43, 17, 43);
}
if ((AverageA) > 2.65) {
u8g2.drawTriangle(9, 26, 0, 37, 17, 37);
}
if ((AverageA) > 3.25) {
u8g2.drawTriangle(9, 20, 0, 31, 17, 31);
}
if ((AverageA) > 3.85) {
u8g2.drawTriangle(9, 14, 0, 25, 17, 25);
}
if ((AverageA) > 4.45) {
u8g2.drawTriangle(9, 8, 0, 19, 17, 19);
}
if ((AverageA) > 5.05) {
u8g2.drawTriangle(9, 2, 0, 13, 17, 13);
}
//down triangles ****************
if ((AverageA) < -0.25)u8g2.drawTriangle(9, 79, 0, 68, 17, 68);
if ((AverageA) < -0.85)u8g2.drawTriangle(9, 85, 0, 74, 17, 74);
if ((AverageA) < -1.45)u8g2.drawTriangle(9, 91, 0, 80, 17, 80);
if ((AverageA) < -2.05)u8g2.drawTriangle(9, 97, 0, 86, 17, 86);
if ((AverageA) < -2.65)u8g2.drawTriangle(9, 103, 0, 92, 17, 92);
if ((AverageA) < -3.25)u8g2.drawTriangle(9, 109, 0, 98, 17, 98);
if ((AverageA) < -3.85)u8g2.drawTriangle(9, 115, 0, 104, 17, 104);
if ((AverageA) < -4.45)u8g2.drawTriangle(9, 121, 0, 110, 17, 110);
if ((AverageA) < -5.05)u8g2.drawTriangle(9, 127, 0, 117, 17, 117);
//Sounds *********************************************

if (((millis() - beep) > Beep_period) && (AverageA > 0.25))
{ // UP TONES
beep = millis();
tone(13, (400 + (125 * AverageA)), 125 - (6 * AverageA));
Beep_period = 1000 - (70 * AverageA);
}
else if (AverageA < -2.0)
{ // DOWN TONES
tone(13, (250 + (20 * AverageA)), 125);
}
u8g2.sendBuffer(); // transfer internal memory to the display

}

2

Because of that?

Please remember to use code tags when posting code

3

The display library needs a large buffer ?

4

Looks like a 128 x 64 display, that will use 1024 bytes of memory for the display buffer. Not sure what is using the remaining memory.

5

The program itself, discounting the display buffer, is using 25% of memory, seems reasonable ........

6

You can reduce the display buffer memory by using a page buffer instead of a full buffer. That does require a few changes to the code - see the examples for the U8g2 library.

75% memory usage is not a problem with the current code, may be a concern if you intend to add additional code.

7

Hi David, Thanks, I've tried the page buffer, it made very little difference, not sure how much to expect?
The 'sensor' part of the code, to be merged, uses 37 and 45% of memory - I think I've got a problem!

8

Not really, just use a more modern Arduino with more memory .......

9

Dohh!
I tried page buffer, the sketch worked with no reduction in memory useage - but I failed to changed the display constructor as required.
Now done and memory useage 43 and 31%.
Thanks for your reply.
Paul H

10

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