ESP32 Forum

Hi, i am trying to use a timer interrupt while i am also sniffing for IEEE 802.11 beacon frames. When i tested the sniffer and the timers separate everything worked fine but when i combined the two i get the following error:
Guru Meditation Error: Core 0 panic'ed (Interrupt wdt timeout on CPU0)
Core 0 register dump:
PC : 0x4008973c PS : 0x00060034 A0 : 0x80089f60 A1 : 0x3ffbe140
A2 : 0x3ffbec64 A3 : 0x0000cdcd A4 : 0xb33fffff A5 : 0x00000001
A6 : 0x00060021 A7 : 0x0000abab A8 : 0x0000cdcd A9 : 0x0000cdcd
A10 : 0x3ffbebe4 A11 : 0x3ffc0d58 A12 : 0x3ffaebe0 A13 : 0x3ffb2d40
A14 : 0x0000002a A15 : 0x3ffb2d10 SAR : 0x0000001e EXCCAUSE: 0x00000005
EXCVADDR: 0x00000000 LBEG : 0x400014fd LEND : 0x4000150d LCOUNT : 0xffffffe2
Core 0 was running in ISR context:
EPC1 : 0x400d224c EPC2 : 0x00000000 EPC3 : 0x00000000 EPC4 : 0x4008973c

Backtrace: 0x4008973c:0x3ffbe140 0x40089f5d:0x3ffbe170 0x4008b16b:0x3ffbe190 0x4008ae41:0x3ffbe1b0 0x400817fe:0x3ffbe1c0 0x400d2249:0x3ff
b2cb0 0x400d16cd:0x3ffb2cd0 0x400d18be:0x3ffb2cf0 0x400d18f9:0x3ffb2d10 0x400d155e:0x3ffb2d30 0x4011a532:0x3ffb2d80 0x4008f9a1:0x3ffb2da0

0x4008b07d:0x3ffb2de0

Core 1 register dump:
PC : 0x4008b972 PS : 0x00060e34 A0 : 0x8008a2bb A1 : 0x3ffbe680
A2 : 0x3ffb82a0 A3 : 0x3ffb8074 A4 : 0x00000001 A5 : 0x00000001
A6 : 0x00060e23 A7 : 0x00000000 A8 : 0x3ffb8074 A9 : 0x3ffb8074
A10 : 0x00000018 A11 : 0x00000018 A12 : 0x00000001 A13 : 0x00000001
A14 : 0x00060e21 A15 : 0x00000000 SAR : 0x00000015 EXCCAUSE: 0x00000005
EXCVADDR: 0x00000000 LBEG : 0x400014fd LEND : 0x4000150d LCOUNT : 0xfffffffd

Backtrace: 0x4008b972:0x3ffbe680 0x4008a2b8:0x3ffbe6a0 0x40088d43:0x3ffbe6c0 0x400d223d:0x3ffbe700 0x400d16cd:0x3ffbe720 0x400d18be:0x3ff
be740 0x400d18d1:0x3ffbe760 0x400d132e:0x3ffbe780 0x4008103d:0x3ffbe7a0 0x400817f5:0x3ffbe7c0 0x400d270f:0x3ffb1fb0 0x4008b07d:0x3ffb1fd0


This is what i get when i decode the stack trace:

PC: 0x4008973a: vTaskSuspendAll at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/freertos/tasks.c line 2143
EXCVADDR: 0x00000000

Decoding stack results
0x4008973a: vTaskSuspendAll at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/freertos/tasks.c line 2143
0x40089f5d: prvAddNewTaskToReadyList at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/freertos/tasks.c line 1197
0x4008b16b: prvProcessTimerOrBlockTask at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/freertos/timers.c line 583
0x4008ae41: pvTaskIncrementMutexHeldCount at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/freertos/tasks.c line 4572
0x400817fe: esp_timer_impl_get_time at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/esp32/esp_timer_esp32.c line 198
0x400d2249: uartFlush at C:\Users\thoma\Documents\ArduinoData\packages\esp32\hardware\esp32\1.0.4\cores\esp32\esp32-hal-uart.c line 343


If anyone knows what the problem is or has a solution that would be very useful.
( I think the problem occurs when the a timer interrupt occurs when the code is executing the interrupt service routine of the sniffer or the other way around. But i am not sure of this.)
The code I used is bellow, thanks!!

code:

#include <Arduino.h>
#include "esp_timer.h" // lib for timermanagement
#include <PriUint64.h>// lib to print 64 bit nr
#include "esp_wifi.h"// lib for Wi-Fi


/*----------------------Random-----------------------*/
#define period 1000000
int curChannel = 1;
int counter=1;
uint8_t MAC_odisee[6]={0x88,0x1D,0xFC,0x30,0xD6,0x90}; // mac adres random router in b225 on channel 1



/*----------------------declarations-----------------------*/

// declare hw timer
hw_timer_t * timer1 = NULL;

//filter for sniffing
const wifi_promiscuous_filter_t filt={
//filter for management frames: frame control= b 0000 0001 = WIFI_PROMIS_FILTER_MASK_MGMT
.filter_mask= WIFI_PROMIS_FILTER_MASK_MGMT
};

// new structure for frame control bytes
typedef struct {
uint16_t version:2;
uint16_t type:2;
uint16_t subtype:4;
uint16_t to_ds:1;
uint16_t from_ds:1;
uint16_t mf:1;
uint16_t retry:1;
uint16_t pwr:1;
uint16_t more:1;
uint16_t w:1;
uint16_t o:1;
}__attribute__((packed)) wifi_ieee80211_frame_ctrl_t;

// new structure for payload of 802.11 frame
typedef struct {
uint8_t timestamp[8]; // timestamp
uint8_t beaconinterval[2]; // beacon interval
uint8_t capabilityinfo[2]; // capability info
uint8_t lengthssid[2];
unsigned char rest[]; // payload met eerste bytes=ssid (ssid heeft variabele lengte!!)
}__attribute__((packed)) wifi_ieee80211_payload;

// new structure for mac header
typedef struct {
wifi_ieee80211_frame_ctrl_t frame_ctrl; // frame control
int16_t duration;
uint8_t addr1[6]; // receiver address
uint8_t addr2[6]; // sender address
uint8_t addr3[6]; // filtering address
int16_t seqctl; // sequence control
unsigned char payload[]; // payload
} __attribute__((packed)) wifi_ieee80211_mac_hdr_t;

// new structure for ieee 802.11 frame
typedef struct {
wifi_ieee80211_mac_hdr_t hdr; // mac header
uint8_t payload[0]; /* network data ended with 4 bytes csum (CRC32) */
}__attribute__((packed)) wifi_ieee80211_packet_t;



/*----------------------functions-----------------------*/

// callback for timer 1
void callbacktimer1(){
counter++;
timerAlarmWrite(timer1, period*counter , false); // set next interrupt
timerAlarmEnable(timer1); // enable interrupt
Serial.print("callback: ");
Serial.println(counter);
}


// callback for wifi sniffer
void sniffercallback(void* buf, wifi_promiscuous_pkt_type_t type) { //This is where packets end up after they get sniffed

//take timestamp
//TODO: controleren of timestamps opgeslaan blijven als de core reset!!
//u<int64_t time = timerRead(timer1);


/*
data is passed to buf
buf contains radio meta data (wifi_pkt_rx_ctrl_trx_ctrl) and the payload
radio meta data can be accessed by pkt->rx_ctrl.member
payload is parsed to multiple data structures
*/

wifi_promiscuous_pkt_t *pkt = (wifi_promiscuous_pkt_t*)buf; // move data from buffer to wifi_promiscuous_pkt_t data type
wifi_ieee80211_packet_t *ipkt = (wifi_ieee80211_packet_t *)pkt->payload; // put packet in wifi_ieee80211_packet_t data type
wifi_ieee80211_mac_hdr_t *hdr = &ipkt->hdr; // put mac header in wifi_ieee80211_mac_hdr_t datatype
wifi_ieee80211_frame_ctrl_t *framecontrol = &hdr->frame_ctrl; // put 2 framecontrol bytes into framecontrol datatype
wifi_ieee80211_payload *payload = (wifi_ieee80211_payload*)&ipkt->payload; // put payload of frame in structure ieee80211_payload datatype

if(framecontrol->subtype==8){
// check if it is the right access point
bool juisteMAC=true;
/*
for(int i=0;i<6;i++){// compare MAC address against adres of masteresp32
if(MAC_odisee!=hdr->addr3){
juisteMAC=false;
}
}*/
if(juisteMAC){// do stuf if it is the right access point

//TODO save timestamp + id !!!!!!!!!





// ------------------------------------------------------------print info---------------------------------------------------------------------

// print ssid
int lengtessid = (payload->lengthssid[0]<<8) | (payload->lengthssid[1]); // bepaal lengte ssid
Serial.println("ssid: ");
char SSID[lengtessid];
for(int i=0; i<lengtessid;i++){
SSID=payload->rest;
Serial.print(SSID);
}
Serial.println();

// print beacon interval
Serial.print("Beacon interval in TU: ");
Serial.print(payload->beaconinterval[0]); //6400 voor 100 TU (1 TU = 1.024 milliseconden)
Serial.println(payload->beaconinterval[1]);

//print mac adres
Serial.print("MAC-adres: ");
for(int i=0;i<6;i++){
Serial.print(hdr->addr3,HEX);
Serial.print(":");
}
Serial.println();

//print id of the puls
Serial.print("id van de puls: ");
uint64_t id;
id= ((uint64_t)(payload->timestamp[7])<<56)+
((uint64_t)(payload->timestamp[6])<<48)+
((uint64_t)(payload->timestamp[5])<<40)+
((uint64_t)(payload->timestamp[4])<<32)+
((uint64_t)(payload->timestamp[3])<<24)+
((uint64_t)(payload->timestamp[2])<<16)+
((uint64_t)(payload->timestamp[1])<<8)+
((uint64_t)(payload->timestamp[0]));


for(int i=7;i>=0;i--){
Serial.print(payload->timestamp,HEX);
Serial.print(",");
}
Serial.print(PriUint64<DEC>(id));


for(int i=0;i<8;i++){
Serial.print(payload->timestamp);
}
Serial.println();

// print MAC-level-timestamp
Serial.print("MAC-level timestamp: ");
Serial.println(pkt->rx_ctrl.timestamp);

// print signal strength
Serial.print("signal strength: ");
Serial.print(pkt->rx_ctrl.rssi);
Serial.println(" dbm");

//print channel
Serial.print("channel: ");
Serial.println(curChannel);
Serial.println("--------------------------------------------------------------next frame-------------------------------------------------");

}
}
}

void setup() {
//initialize timer
timer1 = timerBegin(0, 80, true); // timer_id = 0; prescaler=80 => 1 tick = 1 µs; countUp = true;
timerAttachInterrupt(timer1, &callbacktimer1, true); // atatch callback to timer1
timerAlarmWrite(timer1, period, false); // set compare value for timer
timerAlarmEnable(timer1); // enable timer interrupt

//start Serial
Serial.begin(115200);

//initialize Wi-Fi
wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
esp_wifi_init(&cfg);
esp_wifi_set_storage(WIFI_STORAGE_RAM);
esp_wifi_set_mode(WIFI_MODE_NULL);
esp_wifi_start();
esp_wifi_set_promiscuous(true); // enable promiscuous mode
esp_wifi_set_promiscuous_filter(&filt); // set filter
esp_wifi_set_promiscuous_rx_cb(&sniffercallback); // atatch callback function
esp_wifi_set_channel(curChannel, WIFI_SECOND_CHAN_NONE);// set Wi-Fi channel

}

void loop() {
// put your main code here, to run repeatedly:

}

Hoi, I think your issue is that you're printing something in the timer 'callback' (which actually is an interrupt handler). Printing in an interrupt handler will lead to issues.