UART debugger in the browser
Beetwise reads a UART stream and shows each value as a register.
Every bit of the register is visible and selectable.
A change to a register value goes back to the device over the same port.
The UART debugger step by step
Debug a UART link:
- Select Connect, then select the baud rate of the device.
- Send the values as name and value pairs, one line for each sample.
- Read the bits of each value in the register view.
- Select a bit to change it. The tool writes the new value to the port.
What a broken UART looks like, and where to start
| Symptom | Usual cause | First thing to try |
|---|---|---|
| Nothing arrives | Another program holds the port | Close the other serial monitor |
| Every byte is garbage | The baud rate differs | Match the rate of the device |
| Some bytes are garbage | The clock of the device drifts | Use a lower rate |
| Lines join together | No newline at the end | End every line with a newline |
| Half a line appears | The buffer holds the rest | Send the newline, or flush |
| No port to select | The browser has no Web Serial | Use Chrome, Edge or Opera |
| Bytes arrive reversed | The byte order differs | Swap the bytes of each value |
Where the UART debugger is used
A UART defect is often a wrong baud rate or a wrong bit field, not a wrong program.
A bit view shows a wrong field at once, which a decimal log does not.
A write back to the device tests a register without a new build and flash cycle.
The UART debugger: points to note
- Both sides must use the same baud rate. A wrong rate gives damaged characters.
- A write to a read-only hardware register has no effect. Check the data sheet.
- The expression field cannot change a serial register. Use the register view to change it.
- The tool needs a Chromium browser and an HTTPS page.
The full bit editor
The full editor holds many values, evaluates expressions across them, and reads live values from a serial port.
Open the full editorQuestions about the UART debugger
- Can I write a value back to the device?
- Yes. A change of a register value or of a single bit goes to the serial port.
- How do I use a serial value in a calculation?
- Reference the register as SER0, SER1 and so on in the expression field.
- Do I need to install a driver?
- No. The Web Serial API works in the browser without an install.