MPU Fault when running central coded bluetooth task and ENC28J60 dhcpv4_client task simultaneously

[kienasv]

I am building the coded bluetooth gateway using nrf52840 and ENC28J60. Integrated between two examples:

• https://github.com/nrfconnect/sdk-nrf/tree/master/samples/bluetooth/central_hr_coded
• https://github.com/zephyrproject-rtos/zephyr/tree/master/samples/net/dhcpv4_client

I created two task:

void ethernet_task(void) {
  struct net_if *iface;

  printf("Run dhcpv4 client");

  net_mgmt_init_event_callback(&mgmt_cb, net_handler,
				NET_EVENT_IPV4_ADDR_ADD);
  net_mgmt_add_event_callback(&mgmt_cb);

  iface = net_if_get_default();

  net_dhcpv4_start(iface);

  /* Wait for a lease. */
  k_sem_take(&got_address, K_FOREVER);

  printk("Got IP Address");

  while(1) {
    //printk("ethernet task polling");
    k_msleep(1000);
  }
}

void ble_task(void) {
  int err;

  err = bt_enable(NULL);
  if (err) {
    printk("Bluetooth init failed (err %d)\n", err);
    return;
  }

  printk("Bluetooth initialized\n");

  bt_conn_cb_register(&conn_callbacks);

  scan_init();

  err = bt_scan_start(BT_SCAN_TYPE_SCAN_ACTIVE);
  if (err) {
    printk("Scanning failed to start (err %d)\n", err);
    return;
  }

  printk("Scanning successfully started\n");

  while(1) {
    //printk("ble task polling");
    k_msleep(1500);
  }

}

There is no main function. I start two tasks using:

K_THREAD_DEFINE(ethernet_task_id, 1024, ethernet_task, NULL, NULL, NULL,
		3, 0, 0);
K_THREAD_DEFINE(ble_task_id, 1024, ble_task, NULL, NULL, NULL,
		3, 0, 0);

If I just run one task (comment one K_THREAD_DEFINE of another task to prevent it from running), the running task can work perfectly. But if I let two tasks to run simultaneously , the MPU fault occur and CPU reset.

I am using nRF Connect SDK v1.5.0 with Zephyr SDK v2.4.99-nsc1

�[1B�[9D�[8D�[J[00:00:00.542,663] �[1;31m os: ***** MPU FAULT *****�[0m
�[8D�[J[00:00:00.542,694] �[1;31m os: Data Access Violation�[0m
�[8D�[J[00:00:00.542,694] �[1;31m os: MMFAR Address: 0x30a03�[0m
�[8D�[J[00:00:00.542,694] �[1;31m os: r0/a1: 0x40003000 r1/a2: 0x20007174 r2/a3: 0x00030a03�[0m
�[8D�[J[00:00:00.542,694] �[1;31m os: r3/a4: 0x00000000 r12/ip: 0x20000618 r14/lr: 0x0002ac21�[0m
�[8D�[J[00:00:00.542,724] �[1;31m os: xpsr: 0x81003813�[0m
�[8D�[J[00:00:00.542,724] �[1;31m os: Faulting instruction address (r15/pc): 0x00034688�[0m
�[8D�[J[00:00:00.542,724] �[1;31m os: >>> ZEPHYR FATAL ERROR 0: CPU exception on CPU 0�[0m
�[8D�[J[00:00:00.542,724] �[1;31m os: Fault during interrupt handling
�[0m
�[8D�[J[00:00:00.542,755] �[1;31m os: Current thread: 0x20005718 (idle 00)�[0m

I checked with addr2line, the crash position is /nRFConnectSDK/v1.5.0/modules/hal/nordic/nrfx/drivers/src/nrfx_spi.c:254

It happens on the SPI transfer byte process. I increased thread stack size but the problem still occur.

Does anyone meet this problem? and Do you know any method to find out more information about this problem to solve it?
Thanks.

[Carl Richard]

Hi!

Could you try to experiment a bit with the priorities of the two threads, starting with lowering the ethernet_task priority to 7 for example? I believe the issue could be related to the two threads trying to do time sensitive tasks simultaneously. 

In addition I would like to know how you are interfacing with the ENC28J60. Are you using a library?

Best regards,
Carl Richard

[kienasv]

hi Carl Richard 

Thanks for your help.

I tested with different priorities of two threads, the hard fault still happen right after cpu reset. You can check the video by url: https://streamable.com/k3dbbj

I pushed my code on the github: https://github.com/kienasv/ble_demo
dts in the folder ble_demo_nrf52840.

Is there any possible that make the ble scanning process consume almost CPU so that ethernet task cannot work?

[kienasv]

I forgot. I am interfacing with ENC28J60 using library by define:

CONFIG_NET_L2_ETHERNET=y

CONFIG_ENTROPY_GENERATOR=y

CONFIG_SPI=y

CONFIG_ETH_ENC28J60=y

CONFIG_ETH_ENC28J60_0=y

you can check it on my source code on github.

[Carl Richard]

Hello again!
 
Apologies for the delayed answer. Could you try to increase the thread stack sizes and see if that helps? Try to increase the ENC28J60 stack as well by using CONFIG_ETH_ENC28J60_RX_THREAD_STACK_SIZE in the prj.conf. 

Some more logging output from the ethernet driver could be nice too. You can get that by setting CONFIG_ETHERNET_LOG_LEVEL_DBG=y.

Best regards,
Carl Richard