Hi everyone,
I'm encountering a usage fault on the nRF52840 Featherboard when trying to connect to a network using OpenThread. The issue arises specifically during the execution of the init_networking() function in my network.c file.
The Fault observed:
The section of the code in networking.c which the fault occurs:
#include "networking.h"
// Globals
otInstance *instance;
otUdpSocket udpSocket;
int counter = 0;
K_SEM_DEFINE(network_semaphore, 1, 1); // Define a binary semaphore
// Initialize networking setup, previously the main function logic
void init_networking(void) {
// Take the semaphore to enter the critical section
k_sem_take(&network_semaphore, K_FOREVER);
printk("Initializing OpenThread joiner on Featherboard...\n");
init_adc();
instance = openthread_get_default_instance();
if (instance == NULL) {
printk("Failed to get OpenThread instance\n");
k_sem_give(&network_semaphore); // Give semaphore if initialization fails
return;
}
otError error = otIp6SetEnabled(instance, true);
if (error != OT_ERROR_NONE) {
printk("Failed to enable IP6 interface: %d\n", error);
k_sem_give(&network_semaphore); // Give semaphore if enabling IP6 fails
return;
}
uint16_t panId = CONFIG_OPENTHREAD_PANID;
error = otLinkSetPanId(instance, panId);
if (error != OT_ERROR_NONE) {
printk("Failed to set PAN ID: %d\n", error);
k_sem_give(&network_semaphore); // Give semaphore if setting PAN ID fails
return;
}
printk("Thread network initialized, waiting for joiner to complete.\n");
int attempt_counter = 0;
while (1) {
k_msleep(SLEEP_TIME_MS);
printk("Main loop running\n");
attempt_counter++;
if (instance != NULL){
otDeviceRole role = otThreadGetDeviceRole(instance);
if (role != OT_DEVICE_ROLE_DISABLED && role != OT_DEVICE_ROLE_DETACHED) {
handle_joiner_callback(OT_ERROR_NONE, instance);
break;
}
}
if (attempt_counter >= 50) {
printk("Maximum attempts reached. Performing factory reset.\n");
performFactoryreset();
attempt_counter = 0;
}
}
// Give the semaphore once the critical section is complete
k_sem_give(&network_semaphore);
}
Here's what's happening:
- Objective: Connect the device to a border router (hosted on another device) over OpenThread and send messages via UDP.
- Problem Area: During the network joining process within the
init_networking()function, the device enters a while loop attempting to join the network. - Observed Behavior:
- After a few attempts, a usage fault error occurs, causing the device to reboot.
- Sometimes, it connects after several errors and reboots.
- Other times, it connects without any issues.
- Occasionally, it takes much longer to connect, with no consistent pattern.
- Post-Connection: Once the device successfully joins the network and obtains a child or router role, it sends UDP messages without any problems, and the fault does not recur.
Investigations and Findings:
- I discovered that the issue is linked to the line
CONFIG_FPU=yin my configuration file. Commenting out this line prevents the fault from occurring, and the device operates as expected.
Attempts to Resolve:
- Set
CONFIG_FPU_SHARING=yin the configuration. - Increasing stack sizes
- Implemented mutexes and semaphores to prevent simultaneous usage of the Floating Point Unit (FPU) during the connection process.
Unfortunately, these solutions haven't resolved the issue.
I'm seeking insights into why enabling the FPU (CONFIG_FPU=y) causes this fault during network initialization and how to fix it. Has anyone experienced similar issues with the FPU on the nRF52840 Featherboard when using OpenThread?
Any advice or suggestions would be greatly appreciated.
Best regards,
Saman
