CAN/LABESP32-C3 · USB DEBUGGER● USB DATA STAYS LOCAL

TWO NODES. ONE BUS.

Seeing any
signals yet?

Connect your ESPs via USB and watch the CAN bus.
Debug console and adjustable load tests in your browser.

LIVE / SIGNAL PATH

Your bus in conversation.

The Wokwi diagram shows normal-operation wiring, not an electrical CAN simulation. The virtual DevKit boards have different pin positions from your SuperMini: connect by GPIO numbers. Remove the CTX-GND test jumper before normal operation.

Loading signal diagram …
TX queued · GPIO 5 → CTX RX detected · CANH/CANL + CRX → GPIO 4 USB log data ESP error

The display is based on USB logs, not electrical measurements. TX alone does not confirm reception; ACKs and electrical transmission timing are not shown.

01

Sender

Not connected

Sends the counter with CAN ID 0x123.

Select a USB port in the browser · 115200 baud

02

Receiver

Not connected

RX frames here confirm CAN communication.

Select a USB port in the browser · 115200 baud

EXPERIMENT / 500 KBIT/S

How much gets through?

No load test yet
seconds
TARGET / FPS—
RECEIVED / FPS—
QUEUED / FPS—
Chart series · last 60 seconds

Top: frames/s. Below: counter increases per firmware window; TX pending is the current queue size; accepted and received totals are cumulative. Rejected attempts were never queued. Stop discards waiting TX frames; an in-flight frame may still arrive. Toggle series to compare small values.

CAN throughput, queues and errors over timeLast 60 seconds on a shared time axis. Upper plot: queued and received frames per second. Lower plot: increases in rejected frames, scheduler skips, counter gaps, RX queue full, hardware overruns and bus errors per firmware measurement window; pending frames are the current queue size. Each series can be toggled. Missing reports remain gaps. Hover over a point for its value and measurement window. Frames/s10 0 s10 s20 s30 s40 s50 s60 s Events/window · pending: frames10

Firmware measurement windows · about one status report per second

TX accepted (total)
—
RX received (total)
—
TX queue full / rejected
—
Counter gaps
—
Scheduler skipped
—
TX pending now
—
RX queue full / HW overrun
—
Bus errors sender / receiver
—
TX cancelled at stop
—
TX failed
—

Connect both boards. The load test requires CAN-LAB firmware.

Only for this isolated experimental setup. CAN stays at 500 kbit/s; load frames contain eight data bytes. Target rate and queued frames do not confirm reception. Full TX queues do not prove CAN frame loss. The test stops automatically after the selected duration; the sender then remains stopped. Reconnecting the sender restarts the demo at one frame/s. During load tests, the diagram and measurements use firmware summary reports.

RX-FRAMES / ID 0x1230from both USB consoles
LAST COUNTER—No CAN reception yet
COUNTER GAPS0skipped values in the log
WAITING FOR USB

Connect the receiver, then start the sender.

Live console

0 lines
Quiet so far.
Connect a USB port to see live output.
LIVE · Up to 2,000 lines storedTX queued ≠ CAN reception confirmed
No frames? Check these debugging tips.

USB connected, no output

Briefly press RESET on the ESP, without BOOT. Close other serial monitors. Wrong port? Disconnect and select the other one.

“… waiting for frames”

Check CANH ↔ CANH, CANL ↔ CANL and common ground. GPIO 5 → CTX, GPIO 4 → CRX. Power CAN modules at 3.3 V only.

Check termination

Disconnect both USB power supplies. The WCMCU-230 modules already include bus termination; no external resistors are needed. Expect about 60 Ω between CANH and CANL.

Sender reports Bus-Off

After Bus-Off recovery, the sender resumes the 1-frame/s demo automatically. An interrupted load test stays stopped. Repeated Bus-Off requires checking module power, GPIO connections and the CAN bus. DIAG lines show driver state and error counters; TX_ACK confirms successful CAN transmission with ACK, but not yet reception in the receiver log.