How to use the second I2C-Bus HTTC-AB02S?

#1

How can i use the second I2C-Bus?

I tryed

TwoWire I2Ctwo = TwoWire(1);
I2Ctwo.begin();
I2Ctwo.beginTransmission(STS35_I2C_ADDRESS);
…

but no success!

Greeting

E_T

#2

In Wire.h you can find two reservations … pretty much same thing as other arduino’s.

extern TwoWire Wire;
extern TwoWire Wire1;

#3

Thank you weradus!

I try it with
extern TwoWire Wire1;
Wire1.begin();
…

but no success!

E_T

#4

Have you tried scanning both busses and see what is returned ?

#5

With

Wire.begin and Sensor connected to SDA and SCL i got values!

Then changing to Wire1.begin … and connecting the sensor to SCL2 and SDA2 i got error code 3 at Wire1.endTransmission(true)

E_T

#6

Schematics are a bit vague, but their might not be pull-up resistor on the 2nd I2C bus …

#7

Thank you Weradus, this is a good hint.

The extern pull-up resistors (on sensorboard) are switched on!

I think there is a library problem. I hope, heltec will have a look at this post!

Greeting

E_T

#8

I think i found a mistake. IO8 is connected to the green LED, so it can’t be used für the second I2C-bus! Its used by GPS!

#9

Good observation Ernst, I completely overlooked that.

#10

Yes, IO8 of AB02S is already occupied by GPS, so the second group of IIC cannot be used normally. Use the second group of IIC under normal circumstances, you can refer to this example:
I2C_SET

#11

Hello Shaffer, thank you for the link!

Wire.begin (100000,1) uses the second I2C bus!

But how is the second I2C bus then connected! IO8 is not possible. I tested Wire1.begin() but it didn’t work at IO8 and IO9!

Oled is connected to I2C one and i want to use I2C two for an I2C-sensor, because the sensor don’t work with OLED together.

E_T

#12

In the library of AB02S, the default second group of IIC pins are IO8 and IO9, and the underlying library has been packaged. But because IO8 is occupied by GPS, the second group of IIC cannot be used. You can use a group of IIC to connect multiple IIC devices, and distinguish them by the IIC addresses of different devices.

#13

Theoretically it should be possible to re-route the pins, but that will take some further research, when that feature is available on the used PSOC device …

#14

Just an FYI, I was trying to scan the buses, thinking I would at least see the OLED displays (AB02/AB02s) before adding a new sensor, but no luck,
I did discover you need to init the OLED, then the I2C scan will see it.

In setup() I added:

#define rst GPIO10 // OLED reset pin
pinMode(rst,OUTPUT);
digitalWrite(rst,HIGH);
delay(1);
digitalWrite(rst,LOW);
delay(1);
digitalWrite(rst,HIGH);
delay(1);

#15

Hello @leroyle, I am trying also to see the OLED in a AB02S but have not suceed. Could you share to full code???

Thanks in advance