Hi everybody,
I am trying my best to make my nrf52840dk communicating with an external bmp280 sensor using i2c, but I could not even read the cip id.
Maybe I completely misunderstood how to do it.
Here's my prj.conf:
CONFIG_I2C=y
Here's my nrf52840dk_nrf52840.overlay:
&i2c0 {
mysensor: mysensor@76{
compatible = "i2c-device";
reg = < 0x76 >;
label = "MYSENSOR";
};
};
Neglecting for a moment my main.c, I would like to show that the sensor node is correctly recognized by the build system:
As you can see i2c0 has got a node named mysensor whose i2c address is 0x76. This is what I have found inside the bmp's datasheet in order to choose the right address:
Here you can see the bmp280's pins:
I connected SDO to GND so that the device address is 0x76. As for the rest, here's my physical connections:
- VCC --> VDD
- GND --> GND
- SCL -->P0.27
- SDA -->P0.26
- CSB-->VDD
I decided to tie CSB high because I read this inside the datasheet:
Now here's my main.c:
#include <zephyr.h>
#include <device.h>
#include <devicetree.h>
#include <sys/printk.h>
#include <drivers/i2c.h>
#define SLEEP_TIME_MS 3*1000
#define I2C0_NODE DT_NODELABEL(mysensor)
void main(void)
{
static const struct i2c_dt_spec dev_i2c = I2C_DT_SPEC_GET(I2C0_NODE);
if (!device_is_ready(dev_i2c.bus)) {
printk("I2C bus %s is not ready!\n\r",dev_i2c.bus->name);
return;
}
uint8_t sensor_reading[2]= {0};
uint8_t sensor_regs[2] ={0xEC, 0xD0};
int ret = i2c_write_read_dt(&dev_i2c,&sensor_regs[0],1,&sensor_reading[0],1);
if(ret != 0){
printk("Failed to write/read I2C device address %x at Reg. %x \r\n", dev_i2c.addr,sensor_regs[0]);
}
while (1) {
k_msleep(SLEEP_TIME_MS);
}
}
You are probably wondering about the content of vector sensor_regs...
0xEC should be the first address to be sent according to the following notation...
0xD0 is the address of the id register which I would like to read.
My program returns "Failed to write/read..." every time because ret<0.
I really don't know what to do. I hope I gave you enough information to help me.
Thanks in advance.
Gianmarco
