Zephyr rtos threads

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Revision as of 05:27, 9 October 2021 by Ted (talk | contribs) (^ Issue with Counter Timer in Zephyr Thread - dwt.h)
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Keywords: Zephyr thread analyzer module :: thread resource use :: thread stack monitoring


^ OVERVIEW

Kinda limited tutorials on Zephyr RTOS threads, but seemingly solid documentation on zephyrproject.org site. A specific example starting point may be among Zephyr source tree's samples directory . . . `$ grep -nr k_thread_create ./*` shows thread creation in a SPI Bluetooth driver sample. Path from root Zephyr RTOS source tree is zephyr/drivers/bluetooth/hci.

Also worth noting Zephyr provides a thread analyzer module for Zephyr based apps.


Passing data between Zephyr threads:
On this top level page there is mention of passing data between threads:

Zephyr queues:


^ Zephyr RTOS Thread API

Some Zephyr RTOS API functions to learn:

    • k_sem_take(&lte_connected, K_FOREVER);
    • k_work_schedule(&connect_work, K_NO_WAIT);

Additionally some further Zephyr thread entities and mostly API functions include:

    • k_thread
    • K_THREAD_STACK versus K_KERNEL_STACK
    • k_thread_create()
    • k_thread_
    • k_thread_join()
    • k_thread_abort()
    • k_thread_suspend()
    • k_thread_resume()
    Thread options K_ESSENTIAL, K_SSE_REGS and more . . .

Unsure whether this routine a Zephyr one:

 work_init();


Following non-function entities from aws_iot main.c appear important:

77 static struct k_work_delayable shadow_update_work;
78 static struct k_work_delayable connect_work;
79 static struct k_work shadow_update_version_work;


^ Specific Zephyr documentation pages

Following example code block matches k_thread_create() code in zephyr/drivers/bluetooth/hci/spi.c:519:


^ Example Zephyr Thread Creation

Rough search narrowing in on specific thread creation and use in aws_iot sample project from nRF Connect SDK:

cpguest@ubuntu-vm-0p2:/mnt/host-os-dev-area/pulse-pro/firmware-stage1/aws-iot-stand-alone/src$ grep -nr k_ ./*.c
30:static struct k_work_delayable shadow_update_work;
31:static struct k_work_delayable connect_work;
32:static struct k_work shadow_update_version_work;
150:static void connect_work_fn(struct k_work *work)
166:    k_work_schedule(&connect_work,
170:static void shadow_update_work_fn(struct k_work *work)
186:    k_work_schedule(&shadow_update_work,
190:static void shadow_update_version_work_fn(struct k_work *work)
242:            (void)k_work_cancel_delayable(&connect_work);
258:            k_work_submit(&shadow_update_version_work);
262:            k_work_schedule(&shadow_update_work,
283:            (void)k_work_cancel_delayable(&shadow_update_work);
284:            k_work_schedule(&connect_work, K_NO_WAIT);
335:static void work_init(void)
337:    k_work_init_delayable(&shadow_update_work, shadow_update_work_fn);
338:    k_work_init_delayable(&connect_work, connect_work_fn);
339:    k_work_init(&shadow_update_version_work, shadow_update_version_work_fn);
356:            k_sem_give(&lte_connected);
513:    work_init();
523:    k_sem_take(&lte_connected, K_FOREVER);
528:    k_work_schedule(&connect_work, K_NO_WAIT);

cpguest@ubuntu-vm-0p2:/mnt/host-os-dev-area/pulse-pro/firmware-stage1/aws-iot-stand-alone/src$ grep -n connect_work ./*.c
31:static struct k_work_delayable connect_work;
150:static void connect_work_fn(struct k_work *work)
166:    k_work_schedule(&connect_work,
242:            (void)k_work_cancel_delayable(&connect_work);
284:            k_work_schedule(&connect_work, K_NO_WAIT);
338:    k_work_init_delayable(&connect_work, connect_work_fn);
528:    k_work_schedule(&connect_work, K_NO_WAIT);
cpguest@ubuntu-vm-0p2:/mnt/host-os-dev-area/pulse-pro/firmware-stage1/aws-iot-stand-alone/src$

.
.
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^ Specific Function Associated With Zephyr Thread

150 static void connect_work_fn(struct k_work *work)
151 {
152         int err;
153
154         if (cloud_connected) {
155                 return;
156         }
157
158         err = aws_iot_connect(NULL);
159         if (err) {
160                 printk("aws_iot_connect, error: %d\n", err);
161         }
162
163         printk("Next connection retry in %d seconds\n",
164                CONFIG_CONNECTION_RETRY_TIMEOUT_SECONDS);
165
166         k_work_schedule(&connect_work,
167                         K_SECONDS(CONFIG_CONNECTION_RETRY_TIMEOUT_SECONDS));
168 }
150:static void connect_work_fn(struct k_work *work)
338:    k_work_init_delayable(&connect_work, connect_work_fn);


^ Issue with Counter Timer in Zephyr Thread - dwt.h

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The AWS IoT sample started, version: v1.0.0
Zephyr thread create routine returns 536955992 for LED blink thread,
- SUCCESS - found Kionix accelerometer and device is ready
uart task at loop iteration 0x00000000
LTE cell changed: Cell ID: -1, Tracking area: -1
uart task at loop iteration 0x00000001
uart task at loop iteration 0x00000002
thread_kionix_accel - Kionix sensor reports manufacturer ID string:  " K  i  o  n "
( spaces added around characters, ID four bytes long. )

***
*** TEST 2p1
*** X accel 184, Y accel 65341, Z accel 16409
***
ASSERTION FAIL @ WEST_TOPDIR/zephyr/arch/arm/include/aarch32/cortex_m/dwt.h:103
E: r0/a1:  0x00000004  r1/a2:  0x00000067  r2/a3:  0x00000001
E: r3/a4:  0x00000000 r12/ip:  0xa0000000 r14/lr:  0x00027439
E:  xpsr:  0x41000000
E: Faulting instruction address (r15/pc): 0x00039590
E: >>> ZEPHYR FATAL ERROR 4: Kernel panic on CPU 0
E: Current thread: 0x20014d88 (unknown)

Looking at `dwt.h`:

 88 
 89 /**
 90  * @brief Initialize and Enable the DWT cycle counter
 91  *
 92  * This routine enables the cycle counter and initializes its value to zero.
 93  *
 94  * @return 0
 95  */
 96 static inline int z_arm_dwt_init_cycle_counter(void)
 97 {
 98         /* Clear and enable the cycle counter */
 99         DWT->CYCCNT = 0;
100         DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk;
101 
102         /* Assert that the cycle counter is indeed implemented. */
103         __ASSERT((DWT->CTRL & DWT_CTRL_NOCYCCNT_Msk) != 0,
104                 "DWT implements no cycle counter. "
105                 "Cannot be used for cycle counting\n");
106 
107         return 0;
108 }
109 

What does this mean? Hello, a Nordic Devzone post and reply from Sigurd of Nordic provides an answer to this specific problem: