GIGA: I2C setClock does not appear to do anything

[mjs513]

Using a MPU9250 as my I2c test device I tested using SCL/SDA and SCL1/SDA1. Seems as though i2c clock speed is hardcoded someplace.

SCL/SDA - i2c2
In the overlay default clock is set to fast or 400khz

Setting the clock to 100Khz using setClock(100000) or setClock(i2c_standard) shows an actual clock of 400khz

Setting it 400khz shows same clock

SCL1/SDA1 - i2c4
No default clock is set and seeing 400khz when I do a setclock of 100khz.

EDIT> finally poked around a bit and appears setclock may not be implemented at least I can not find where?

[mjs513]

To resolve the setClock issue I implemented this piece of code for set Clock in wire.cpp

void arduino::ZephyrI2C::setClock(uint32_t freq) {
    uint8_t speed = 	I2C_SPEED_STANDARD;
	if(freq >  0x06u ) {
		if(freq == 100000) {
		  speed = I2C_SPEED_STANDARD;
		} else if(freq == 400000) {
		  speed = I2C_SPEED_FAST;
		} else if(freq == 1000000) {
		  speed = I2C_SPEED_FAST_PLUS;
		} else {
		  speed = I2C_SPEED_STANDARD;
		}
	} else {
		speed = (uint8_t) freq;
	}
	uint32_t i2c_cfg = I2C_MODE_CONTROLLER |
					I2C_SPEED_SET(speed);

	if (i2c_configure(i2c_dev, i2c_cfg)) {
		//Serial.println("Failed to configure i2c interface.");
	}
}

also had to add this to llext_exports.c

FORCE_EXPORT_SYM(__aeabi_ldivmod);

seems to be working for 100khz and 400khz. Tried 1Mhz but my LA read 111khz?? Tested on Wire and Wire1 with the following sketch:

/* Blink inbuilt LED example */

#include <Arduino.h>
#include <LibPrintf.h>
#include "Wire.h"

void setup()
{
	printf("\n\nSetup begins\n");
	Wire1.begin();
  Wire1.setClock(400000);
	// initialize the LED pin as an output:

	// initialize the pushbutton pin as an input:
	// pinMode(buttonPin, INPUT);
	// pinMode(ledPin, OUTPUT);
	Wire1.beginTransmission(0x53);
	Wire1.write(0x2C);
	Wire1.write(0x08);
	Wire1.endTransmission();

	Wire1.beginTransmission(0x53);
	Wire1.write(0x31);
	Wire1.write(0x08);
	Wire1.endTransmission();

	Wire1.beginTransmission(0x53);
	Wire1.write(0x2D);
	Wire1.write(0x08);
	Wire1.endTransmission();
	printf("\n\nSetup COMPLETE\n\n\n");
}

void loop()
{
	Wire1.beginTransmission(0x53);
Wire1.write(0x32); 
Wire1.endTransmission();
// printf("\n\nrequesting from 53\n\n\n");
Wire1.requestFrom(0x53, 1);
byte x0 = Wire1.read();

Wire1.beginTransmission(0x53);
Wire1.write(0x33); 
Wire1.endTransmission();
Wire1.requestFrom(0x53, 1);
byte x1 = Wire1.read();
x1 = x1 & 0x03;

uint16_t x = (x1 << 8) + x0;
int16_t xf = x;
if(xf > 511)
{
xf = xf - 1024;
}
float xa = xf * 0.004;
printf("\n\nX = %f\n",xa);
// Serial.print("X = "); 
// Serial.print(xa);
// Serial.print(" g"); 
// Serial.println(); 


Wire1.beginTransmission(0x53);
Wire1.write(0x34); 
Wire1.endTransmission();
Wire1.requestFrom(0x53, 1);
byte y0 = Wire1.read();

Wire1.beginTransmission(0x53);
Wire1.write(0x35); 
Wire1.endTransmission();
Wire1.requestFrom(0x53, 1);
byte y1 = Wire1.read();
y1 = y1 & 0x03;

uint16_t y = (y1 << 8) + y0;
int16_t yf = y;
if(yf > 511)
{
yf = yf - 1024;
}
float ya = yf * 0.004;
// printk("Y = %f\n",ya);
printf("Y = %f\n",ya);
// printf("\n\nYa = %f\n\n\n",ya);
// Serial.print("Y = "); 
// Serial.print(ya);
// Serial.print(" g"); 
// Serial.println(); 

Wire1.beginTransmission(0x53);
Wire1.write(0x36); 
Wire1.endTransmission();
Wire1.requestFrom(0x53, 1);
byte z0 = Wire1.read();

Wire1.beginTransmission(0x53);
Wire1.write(0x37); 
Wire1.endTransmission();
Wire1.requestFrom(0x53, 1);
byte z1 = Wire1.read();
z1 = z1 & 0x03;

uint16_t z = (z1 << 8) + z0;
int16_t zf = z;
if(zf > 511)
{
zf = zf - 1024;
}
float za = zf * 0.004;
printf("Z = %f\n\n",za);
// Serial.print("Z = "); 
// Serial.print(za);
// Serial.print(" g"); 
// Serial.println(); 
// Serial.println(); 
delay(2);

}

[facchinm]

Hi Mike, thanks for the investigation! Can I ask you to prepare a PR for the setClock implementation? As usual, to preserve proper attribution 🙂 Thank you!

[mjs513]

Done. If you want to close not an issue