I moved from SDK 7 to SDK 9. I'm using timers with SDK7
APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_MAX_TIMERS, APP_TIMER_OP_QUEUE_SIZE, true);
err_code = app_timer_create(&timer_1s_id, APP_TIMER_MODE_REPEATED, timer_1s_timeout_handler);
APP_ERROR_CHECK(err_code);
the last parameter in APP_TIMER_INIT is not the same in the two SDK, so just like given in examples, I just put NULL
but the timer is not working anymore