I am attempting to write a basic I2C program using Zephyr, but I am currently unable to sent a single byte over I2C. The program hangs after the first clock falling & rising edge.

I'm using external 1K pullups, and have a BME680 device on the other end. I observe the same behavior on the bus with or without the BME680 device.

Am I doing something wrong?

prj.conf

CONFIG_NEWLIB_LIBC=y

CONFIG_PRINTK=y

CONFIG_HAS_SEGGER_RTT=y

CONFIG_USE_SEGGER_RTT=y

CONFIG_RTT_CONSOLE=y

CONFIG_UART_CONSOLE=n



# nRF5340 board config

CONFIG_TRUSTED_EXECUTION_SECURE=y



CONFIG_BT=n

CONFIG_TIMESLICING=n

CONFIG_DEVICE_POWER_MANAGEMENT=y

CONFIG_SYS_POWER_MANAGEMENT=y

CONFIG_SYS_POWER_DEEP_SLEEP_STATES=y

CONFIG_DEVICE_POWER_MANAGEMENT=y



CONFIG_I2C=y

CONFIG_I2C_1=y

main.c

#include 
#include 
#include <sys/printk.h>
#include <drivers/i2c.h>

/* Application main Thread */
int main(void)
{
  struct device *p_i2c = device_get_binding("I2C_1");
  u32_t dev_config = I2C_SPEED_SET(I2C_SPEED_STANDARD) | I2C_MODE_MASTER;
  int res = i2c_configure(p_i2c, dev_config);
  if (res)
  {
    return res;
  }
  struct i2c_msg msgs[2];
  u8_t data[2][2];
  data[0][0] = 0x01; // register address
  data[0][1] = 0x00;
  msgs[0].buf = data[0];
  msgs[0].len = 2U;
  msgs[0].flags = I2C_MSG_WRITE | I2C_MSG_STOP;

  data[1][0] = 0x4;
  data[1][1] = 0xff;
  msgs[1].buf = data[1];
  msgs[1].len = 2U;
  msgs[1].flags = I2C_MSG_WRITE | I2C_MSG_STOP;

  int i = i2c_transfer(p_i2c, &msgs[0], 2, 0x77);
  if  (i)
    printk("transfer failed");
  return 0;
}

On 1/5/20 4:30 AM, Martin Kozusky [newsgroups] wrote:

1 - what is the best solution to call my function every 1ms (or will
it be 1.007ms?), is it ok just to use k_timer? Is "next expiration
time" calculated just by adding period to current time (that would
make a big time diff after many calls) or does it use
k_uptime_get*number of expirations to calculate next expiration
time?

Periodic k_timer's do not work in fractional ticks, no. If you
schedule a 1000ms timeout it will be rounded up internally to exactly
33 hardware cycles, and that process will repeat each cycle.  So you
would see the ~993 Hz tick rate you calculated.  If you want to work
in fractional ticks, the application needs to do that math itself.

2 - what is the best solution for most precise long-term time
keeping?  Let's say i don't want more that 1 minute diff in 20
days. Can I just use k_uptime_get?

Long term time is kept as a 64 bit count of ticks, so it's not subject
to the kind of round-off errors that periodic timers are.  As long as
your app isn't dropping or delaying the counter interrupts, the uptime
value should be as accurate as your crystal is.

If you want to get 1 callback per second as a long term average, you
can (with care) compute your timeout as an offset from system start or
some other time reference instead of "now" (i.e. the Nth timeout will
happen at "N * 1000ms", plus a little precision slop due to the clock
mismatch).  There's actually an API change which will make this kind
of code significantly easier, see
https://github.com/zephyrproject-rtos/zephyr/issues/21305

As far as using a different oscillator to drive the timer, that's
possible but requires some driver fiddling.  I'll let the Nordic folks
speak to that.  One option might be to use the generic ARM SysTick
driver, which doesn't have the rate mismatch issues of the 32kHz
timer, but doesn't have the low power idle characteristics.

Andy

1 - what is the best solution to call my function every 1ms (or will
it be 1.007ms?), is it ok just to use k_timer? Is "next expiration
time" calculated just by adding period to current time (that would
make a big time diff after many calls) or does it use
k_uptime_get*number of expirations to calculate next expiration
time?

2 - what is the best solution for most precise long-term time
keeping? Let's say i don't want more that 1 minute diff in 20
days. Can I just use k_uptime_get?

Hi,

I am building a device driver for Zephyr and when calling the macro, DEVICE_GET(), like DEVICE_GET(my_dev), I get a build error complaining about undefined __device_my_dev.
I tried to locate where the variable is assembled during the build process but have no luck so far.

I have placed the following in the driver source code:

DEVICE_INIT(my_dev, CONFIG_MYDEV_NAME, my_dev_init,
my_dev_device_ctrl, NULL,
APPLICATION, CONFIG_MYDEV_INIT_PRIORITY);

Could you please shed some light on where to look for what might go
wrong?

Thanks,
Justin