ESP32 Packet Format & DataNet Protocol

📡 ESP32 Packet Format & Protocol Details

🔗 Event Data Packet Structure

HEADER

2 bytes

Magic: 0xABCD

PACKET_ID

2 bytes

Sequence number

ON_TIMESTAMP

4 bytes

Microseconds

OFF_TIMESTAMP

4 bytes

Microseconds

EVENT_COUNT

4 bytes

Binary counter

CHECKSUM

2 bytes

CRC16

Total packet size: 18 bytes | Block size: 10-100 packets (180-1800 bytes)

🚀 ESP32 Firmware Event Capture

// ESP32 Interrupt Handler for Binary Input volatile uint32_t on_timestamp = 0; volatile bool waiting_for_off = false; EventPacket event_buffer[BLOCK_SIZE]; volatile int buffer_index = 0; void IRAM_ATTR binary_input_isr() { uint32_t current_time = esp_timer_get_time(); // microseconds if (digitalRead(BINARY_INPUT_PIN) == HIGH) { // Rising edge - store ON timestamp on_timestamp = current_time; waiting_for_off = true; } else if (waiting_for_off) { // Falling edge - capture complete event EventPacket* packet = &event_buffer[buffer_index]; packet->header = 0xABCD; packet->packet_id = ++sequence_counter; packet->on_timestamp = on_timestamp; packet->off_timestamp = current_time; packet->event_count = read_binary_counter(); // Sample counter NOW packet->checksum = calculate_crc16(packet); buffer_index++; waiting_for_off = false; // Check if block is full if (buffer_index >= BLOCK_SIZE) { xQueueSendFromISR(transmit_queue, &event_buffer, NULL); buffer_index = 0; // Reset for next block } } }

⏱️ Event Capture Timing Sequence

Binary Input
HIGH

→

Store
ON timestamp

→

Binary Input
LOW

→

Capture
OFF timestamp

→

Sample
Counter

→

Store
Event Packet

→

Block Full?
Transmit

📤 Block Transmission Protocol (UDP)

Block Header Format:

Field	Size	Description	Example
Block Magic	4 bytes	0xDEADBEEF	Block identifier
Block ID	4 bytes	Sequential	0x00000001
Packet Count	2 bytes	Events in block	50
Timestamp Base	4 bytes	Block start time	System uptime
Event Packets	N * 18 bytes	Event data array	Variable
Block CRC	4 bytes	Integrity check	CRC32

⚙️ Control Register Map

0x1000 - CONTROL_MODE

Bit 0: Enable event capture
Bit 1: Reset counter
Bit 2: Trigger calibration

0x1004 - BLOCK_SIZE

Number of events per transmission block (10-100)
Default: 25 events

0x1008 - THRESHOLD_VALUE

Digital input threshold voltage (mV)
For add-on board signal conditioning

0x100C - COUNTER_PRESCALER

Binary counter clock divider
Controls counting resolution

0x1010 - STATUS_FLAGS

Bit 0: Buffer overflow
Bit 1: WiFi connected
Bit 2: Counter running

0x1014 - DEBUG_OUTPUT

Test signal generation
For add-on board verification

🔄 PC ↔ ESP32 Communication Protocol

# Python Device Communication Service import socket import struct import asyncio class ESP32Protocol: def __init__(self, esp32_ip, port=8888): self.esp32_ip = esp32_ip self.port = port self.sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) def write_register(self, address, value): # Command format: [CMD][ADDR][VALUE] packet = struct.pack('= 18: # Minimum block header block = self.parse_event_block(data) await callback(block) def parse_event_block(self, data): # Parse block header magic, block_id, count, timestamp_base = struct.unpack('

📊 Analysis Service Data Processing

# Event Data Service - Pulse Analysis import numpy as np from collections import deque class PulseAnalyzer: def __init__(self, window_size=1000): self.pulse_widths = deque(maxlen=window_size) self.frequencies = deque(maxlen=window_size) self.counter_deltas = deque(maxlen=window_size) self.last_counter = 0 def process_event_block(self, block): events = block['events'] for event in events: # Calculate pulse characteristics pulse_width = event['pulse_width'] # microseconds counter_delta = event['event_count'] - self.last_counter self.pulse_widths.append(pulse_width) self.counter_deltas.append(counter_delta) self.last_counter = event['event_count'] # Calculate frequency from recent events if len(events) > 1: time_span = events[-1]['off_timestamp'] - events[0]['on_timestamp'] frequency = (len(events) - 1) * 1e6 / time_span # Hz self.frequencies.append(frequency) # Return analysis results for UI feedback return { 'avg_pulse_width': np.mean(self.pulse_widths) if self.pulse_widths else 0, 'frequency': np.mean(self.frequencies) if self.frequencies else 0, 'counter_rate': np.mean(self.counter_deltas) if self.counter_deltas else 0, 'pulse_jitter': np.std(self.pulse_widths) if len(self.pulse_widths) > 1 else 0 }