Hi all, I am trying to get 5 u8g2 0.66" OLEDs to work using one TCA9548A board. I can get a single one to print OK but when I come to try and get them to work with the multiplexer I am getting everything to compile OK but get nothing displayed. I know the hardware works because I have tested that out with a known working sketch so I am sure it is down to my poor coding
This is what I have so far, and I have tried it also without the second set of curly brackets between multiplexer instance callouts
#include <Arduino.h>
#include <U8g2lib.h>
#include <Wire.h>
#define TCA9548A 0x70
void tcaselect(uint8_t i) {
if (i > 7) return;
Wire.beginTransmission(TCA9548A);
Wire.write(1 << i);
Wire.endTransmission();
}
U8G2_SSD1306_128X64_NONAME_F_SW_I2C u8g2(U8G2_R3, /* clock=*/SCL, /* data=*/SDA, /* reset=*/U8X8_PIN_NONE); // All Boards without Reset of the Display R3 refers to 270 deg text rotation
void setup() {
for (int i = 0; i <= 7; i++) {
tcaselect(i);
u8g2.begin();
Wire.begin();
}
{
tcaselect(2); //multiplex the required OLED
u8g2.clearBuffer();
u8g2.setFont(u8g2_font_ncenB08_tr);
u8g2.drawStr(20, 50, "2"); // 0 left, 0 top max appx 100
u8g2.sendBuffer();
delay(1000);
}
{
tcaselect(3); //multiplex the required OLED
u8g2.clearBuffer();
u8g2.setFont(u8g2_font_ncenB08_tr);
u8g2.drawStr(20, 50, "3"); // 0 left, 0 top max appx 100
u8g2.sendBuffer();
delay(1000);
}
{
tcaselect(4); //multiplex the required OLED
u8g2.clearBuffer();
u8g2.setFont(u8g2_font_ncenB08_tr);
u8g2.drawStr(20, 50, "4"); // 0 left, 0 top max appx 100
u8g2.sendBuffer();
delay(1000);
}
{
tcaselect(5); //multiplex the required OLED
u8g2.clearBuffer();
u8g2.setFont(u8g2_font_ncenB08_tr);
u8g2.drawStr(20, 50, "5"); // 0 left, 0 top max appx 100
u8g2.sendBuffer();
delay(1000);
}
{
tcaselect(6); //multiplex the required OLED
u8g2.clearBuffer();
u8g2.setFont(u8g2_font_ncenB08_tr);
u8g2.drawStr(20, 50, "6"); // 0 left, 0 top max appx 100
u8g2.sendBuffer();
delay(1000);
}
{
tcaselect(7); //multiplex the required OLED
u8g2.clearBuffer();
u8g2.setFont(u8g2_font_ncenB08_tr);
u8g2.drawStr(20, 50, "7"); // 0 left, 0 top max appx 100
u8g2.sendBuffer();
delay(1000);
}
}
void loop(void) {
}
Clarify that please. Do you mean you have 5 OLEDs connected and a sketch which selects one of the 5 channels on the mux and displays something on one display? And you have tested that individually in each of the 5 channels/OLEDs?
Also please clarify what you wanted to do with your 5 OLEDs. Do you want them to display different images/text or should all of them display the same image/text at all times?
My suspicion at this point is that the problem could be that your code only creates and uses a single oled object, and it should be creating 5 of them (an array of 5 objects would be sensible).
However, even with the u8g2 library, there might be insufficient ram memory on a small Arduino like Uno/Nano.
My suggestion would be to try to get 2 displays working before you increase that to 3, 4, and finally 5. That way, memory won't be a problem, at least to begin with.
To confirm, I have a working array based sketch that will (from a sim game) get data and then select the correct .bmp from the .h file and display it on the correct OLED. It works perfectly, and it is working on the hardware that I am using for the sketch above.
I need a sketch that takes character strings from the game and then sends them to the corresponding OLED (take a look at the attached picture, the working OLEDs are using the sketch described above when outputs are zero) for a VHF panel representation
The sketch attached is just a test sketch, I want the OLED at address 2 to print "2", at address 3 to print "3" etc. I am happy to get just two working and start from there, as the others would simply be repetition with different callouts
As for memory, the u8g2 library is big but the 328 Nano seems to handle it without a problem, it says some 43% of memory used
I think the "_F_" in the constructor name may mean that a full frame buffer is used in memory. This will require 1K of memory per display, so if 5 objects are used, an Uno/Nano won't have enough.
Also I think the "_SW_" may mean using software i²c instead of hardware. Was that intentional, and if so, why?
