Sensor cadence

Functions
void	ai_engine_set_sensor_rate (uint32_t interval_ms)
	Set the accelerometer feed interval; the only legal sender on s_rate_msg.
void	ai_engine_resume_sensor (void)
	Standalone resume of the default cadence; never back-to-back with a rate set.

Detailed Description

Two functions that share one CY_SECTION_SHAREDMEM message buffer (s_rate_msg) and one asynchronous Cy_IPC_Pipe_SendMessage. That single fact is the whole contract of this topic.

Variant

mtb-mpy and mtb-only

Function Documentation

ai_engine_set_sensor_rate()

void ai_engine_set_sensor_rate

(

uint32_t

interval_ms

)

Set the accelerometer feed interval; the only legal sender on s_rate_msg.

Set the accelerometer feed interval (20 = 50 Hz model rate, 100 = 10 Hz dashboard). Eva Kit drives a local LVGL timer; AI Kit sends an IPC rate request to CM33. Callable from any CM55 task.

Contract

Sets the accelerometer feed interval — 20 (50 Hz model rate) or 100 (10 Hz dashboard). AI Kit sends an op=2 IPC rate request to CM33; Eva Kit drives a local LVGL timer. Callable from any CM55 task. It must be the only IPC sender on the shared s_rate_msg buffer — never call it back-to-back with ai_engine_resume_sensor(): the send is asynchronous, CM33 reads the buffer by pointer after the call returns, and resume's leading memset zeroes an in-flight op=2 so CM33 reads data[0] == 0 = PAUSE (ai_engine.c:522-536). All five shipped call sites (deepcraft_task.c:665,:688,:765,:805,:822) pass the value derived by dc_desired_sensor_rate(), which walks the active set and raises to 50 Hz if any member is AI_SENSOR_IMU. The rate is asserted only inside the ai_engine_start() success branch, walked down on every ai_engine_stop(), and re-asserted every 2 s as self-healing.

Variant

mtb-mpy and mtb-only

Origin

Lifted from deepcraft_task.c:805 and the re-assert at :816-823 (compiled into the prebuilt archive; not shipped as source).

ai_engine_resume_sensor()

void ai_engine_resume_sensor

(

void

)

Standalone resume of the default cadence; never back-to-back with a rate set.

Restore the default sensor cadence after a model session.

Contract

Restores the default sensor cadence after a model session by sending an op=1 resume message. No caller exists anywhere in shipped firmware (absent from consumer_must_provide.txt; the sim stub sim_ai_engine_stub.c:121 is a definition, not a call). Its own definition comment is an explicit anti-usage rule: "DO NOT call this immediately after ai_engine_set_sensor_rate()" — the shared-buffer hazard above froze the pure-MicroPython Edge AI feed (result() == None) on real hardware. It is also unnecessary after a rate change: set_sensor_rate's CM33 handler already clears the pause and resumes the push task atomically. The correct use is a standalone send with nothing else in flight on s_rate_msg (a page-leave path that wants no rate change). CM55 task context.

Variant

mtb-mpy and mtb-only

Example (authored — no shipped call site)

The example below teaches the anti-pattern: the boxed WRONG sequence is what not to write, and the single call that follows is the only legal shape.

__attribute__((used))
static void bento_ex_ai_engine_resume_sensor(void)
{
    /* WRONG — the shared-buffer hazard (see the box above):
     *
     *   ai_engine_set_sensor_rate(100u);   // op=2, in flight...
     *   ai_engine_resume_sensor();         // memset kills it -> PAUSE
     *
     * RIGHT — set_sensor_rate alone already resumes the push task:
     *
     *   ai_engine_set_sensor_rate(100u);   // walk down to dashboard rate
     *
     * RIGHT — resume as a standalone message, nothing else in flight
     * on s_rate_msg (page-leave path, no rate change wanted): */
    ai_engine_resume_sensor();
}