WiFi promiscuous timestamp differs by 140+ms

[PavelDrabek]

Board

ESP32 Dev Module

Device Description

Plain module ESP32-D0WDQ6 (revision 1)

Hardware Configuration

nothing is attached

Version

v2.0.5

IDE Name

Arduino IDE

Operating System

Windows 11 Pro

Flash frequency

40MHz

PSRAM enabled

no

Upload speed

115200

Description

Timestamp stored in wifi_pkt_rx_ctrl_t (from wifi_promiscuous_pkt_t) received in wifi promiscuous rx callback function differs from micros() called immediately in that function by more than 140,000 microseconds but code is running smoothly. I would expect it differs by 10 microseconds at most.

Also micros() returns unsigned long and timestamp in wifi_pkt_rx_ctrl_t is unsigned int which might cause some issues when running for a long time.

Sketch

#include <WiFi.h>
#include <esp_wifi.h>

void promiscuous_rx_cb(void *buf, wifi_promiscuous_pkt_type_t type) {
  unsigned long t = micros();

  const wifi_promiscuous_pkt_t *ppkt = (wifi_promiscuous_pkt_t *)buf;
  unsigned int timestamp = ppkt->rx_ctrl.timestamp;

  String type_str;
  switch(type){
    case WIFI_PKT_MGMT: type_str = "WIFI_PKT_MGMT"; break;
    case WIFI_PKT_CTRL: type_str = "WIFI_PKT_CTRL"; break;
    case WIFI_PKT_DATA: type_str = "WIFI_PKT_DATA"; break;
    case WIFI_PKT_MISC: type_str = "WIFI_PKT_MISC"; break;
  }

  Serial.printf("rx_cb is called: %s\t rt:%u cbt: %lu, tdiff: %lu\n", type_str, timestamp, t, (t - timestamp));
}

void setup() {
  Serial.begin(115200);
  
  WiFi.mode(WIFI_STA);

  esp_wifi_set_promiscuous(true);
  esp_wifi_set_promiscuous_rx_cb(&promiscuous_rx_cb);
}
 
void loop() {

}

Debug Message

22:30:59.842 -> rx_cb is called: WIFI_PKT_MGMT	 rt:117792901 cbt: 117938159, tdiff: 145258
22:30:59.874 -> rx_cb is called: WIFI_PKT_MGMT	 rt:117792901 cbt: 117963029, tdiff: 170128
22:30:59.874 -> rx_cb is called: WIFI_PKT_MGMT	 rt:117792901 cbt: 117970676, tdiff: 177775
22:30:59.907 -> rx_cb is called: WIFI_PKT_MGMT	 rt:117834673 cbt: 117980429, tdiff: 145756
22:30:59.907 -> rx_cb is called: WIFI_PKT_MGMT	 rt:117848847 cbt: 117990243, tdiff: 141396
22:30:59.938 -> rx_cb is called: WIFI_PKT_MGMT	 rt:117872995 cbt: 118010494, tdiff: 137499
22:30:59.938 -> rx_cb is called: WIFI_PKT_MGMT	 rt:117892352 cbt: 118035762, tdiff: 143410
22:30:59.970 -> rx_cb is called: WIFI_PKT_MGMT	 rt:117892352 cbt: 118040876, tdiff: 148524
22:30:59.970 -> rx_cb is called: WIFI_PKT_MGMT	 rt:117892352 cbt: 118065452, tdiff: 173100
22:31:00.002 -> rx_cb is called: WIFI_PKT_MGMT	 rt:117892352 cbt: 118082899, tdiff: 190547
22:31:00.002 -> rx_cb is called: WIFI_PKT_MGMT	 rt:117892352 cbt: 118092617, tdiff: 200265
22:31:00.045 -> rx_cb is called: WIFI_PKT_MGMT	 rt:117957417 cbt: 118094616, tdiff: 137199
22:31:00.045 -> rx_cb is called: WIFI_PKT_MGMT	 rt:117975395 cbt: 118112903, tdiff: 137508
22:31:00.077 -> rx_cb is called: WIFI_PKT_MGMT	 rt:117998796 cbt: 118142955, tdiff: 144159
22:31:00.077 -> rx_cb is called: WIFI_PKT_MGMT	 rt:118024925 cbt: 118167859, tdiff: 142934
22:31:00.118 -> rx_cb is called: WIFI_PKT_DATA	 rt:118024925 cbt: 118169032, tdiff: 144107

Other Steps to Reproduce

No response

I have checked existing issues, online documentation and the Troubleshooting Guide

• I confirm I have checked existing issues, online documentation and Troubleshooting guide.

[lbernstone]

This is an ESP-IDF function. You will have better luck asking at https://github.com/espressif/esp-idf/issues

[mrengineer7777]

esp_wifi_types.h:
unsigned timestamp:32; /**< timestamp. The local time when this packet is received. It is precise only if modem sleep or light sleep is not enabled. unit: microsecond */

uint32_t is too small to store microseconds or milliseconds. Could it be UTC seconds? [Edit: unlikely, see see it changing in your example]

I believe the correct format specifier for long unsigned is "%llu", but I don't think Arduino core supports that. I haven't been able to get it to work.

[Parsaabasi]

Hello,

Due to the overwhelming volume of issues currently being addressed, we have decided to close the previously received tickets. If you still require assistance or if the issue persists, please don't hesitate to reopen the ticket.

Thanks.