Hi,
I have an ESP32 talking to an SC7A20 accelerometer via I2C, the same HW will succesfully talk to an SSD1306 OLED display.
The problem starts when I try to combine the two together in one sketch as neither the display or the accelerometer will work.
I changed the OLED instance from U8X8_SSD1306_128X64_NONAME_SW_I2C u8x8(/* clock=*/5, /* data=*/4, /* reset=*/U8X8_PIN_NONE);
to U8X8_SSD1306_128X64_NONAME_HW_I2C u8x8(U8X8_PIN_NONE)
but this made no difference.
I'm assuming there is some type of conflict on the I2C bus when both are used on the I2C bus at the same time, is there a way of getting them to work together?
Here are the parts of the latest code I tried that doesn't work
#include <Wire.h>
#include <Arduino.h>
#include <U8x8lib.h>
//U8X8_SSD1306_128X64_NONAME_SW_I2C u8x8(/* clock=*/5, /* data=*/4, /* reset=*/U8X8_PIN_NONE); // OLEDs without Reset of the Display
U8X8_SSD1306_128X64_NONAME_HW_I2C u8x8(U8X8_PIN_NONE);
#include "SparkFun_LIS2DH12.h" //Click here to get the library: http://librarymanager/All#SparkFun_LIS2DH12
#define LIS2DH12_ID = 0x11;
SPARKFUN_LIS2DH12 accel; //Create instance
void setup() {
Wire.begin(4, 5);
u8x8.begin();
//u8x8.setBusClock(1);
u8x8.setFlipMode(0);
u8x8.setFont(u8x8_font_8x13B_1x2_f);
//u8x8.setFont(u8x8_font_profont29_2x3_f);
// initialize serial communication with computer:
Serial.begin(115200);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB
}
Serial.println("SparkFun Accel Example");
if (accel.begin() == false) {
//Serial.println(accel.LIS2DH12_ID);
Serial.println("Accelerometer not detected. Are you sure you did a Wire1.begin()? Freezing...");
while (1)
;
}
From the error message, the Sparkfun library seems to assume that the sensor is connected to Wire1. If so, that is a problem. Check the library code, and/or consider using a different library.
From the error message, the Sparkfun library seems to assume that the sensor is connected to Wire1. If so, that is a problem. Check the library code, and/or consider using a different library.
I understand why you say that but it works fine without the OLED code added.
If you look at the library header file you will see it only contains one variant of begin:
bool begin(uint8_t address = ACCEL_DEFAULT_ADR, TwoWire &wirePort = Wire); //Begin comm with accel at given I2C address
You use it without passing any parameters:
`if (accel.begin() == false) {`
That compiles okay because the declaration of begin in the header file contains default values which will be used if you don't specify any parameters.
I've not looked in detail at what begin does, but I didn't spot anything to make me think there would be a conflict.
That's strange. In post #8 you can see that the default value used by begin is Wire, not Wire1. I wonder why the error message assumes the user didn't initialise Wire1
The Sparkfun library is configured for two different I2C addresses, depending on an address input setting. I don't see how either of these could match up with the 0x19 address reported by the I2C scanner program.
/** I2C Device Address 8 bit format if SA0=0 -> 31 if SA0=1 -> 33 **/
#define LIS2DH12_I2C_ADD_L 0x31U
#define LIS2DH12_I2C_ADD_H 0x33U
Initailly the sparkfun library fails to talk to the SC7A20 due to the device ID being different to the sparkfun device, it took me a while to find that problem and fix it.
I think it's the usual 7bit address vs 8bit address issue.
This is a scope trace I took ages ago when I first tried using I2C with Arduino. The line of text from #1 Start to #11 STOP is my annotation, not Picoscope's decode.
For the default 7 bit address of 0x19, if we multiply it by 2 we get 0x32, then presumably for some reason they assume it's a read and add 1 to get 0x33.
By device ID I didn't mean the I2C address, there is a device ID in a register, the sparkfun device ID is 0x33 but the SC7A20 reports 0x11 as its ID,which is checked during the accel.begin function.
I added the define for the SC7A20 in the sketch to overide the library definition.
