• General commands
  • Beginner
  • 3 min
  • Serial CLI

Recipe · Beginner · General commands

How to enable and disable pull-ups

Use P and p to manage context-sensitive pull-ups for UART RX, HDUART IO, 1-Wire DQ, I2C SDA/SCL or SPI MISO.

GPIO pinout diagram for wiring checks.
The P and p commands are context-sensitive helpers for common bus inputs.
Step 1

Commands

These commands are documented as global or quick-start commands.

Result

What it means

If the command returns the expected output, the firmware and terminal session are ready for the next workflow.

Troubleshooting

  • Confirm the active mode before running P.
  • Use external pull-ups for long wires or multiple devices.
  • Disable pull-ups with p if they disturb the target circuit.

Next steps

  • Try the same workflow on a known safe pin or target.
  • Save the useful command as a note or alias.
  • Move to the protocol-specific recipe once the basics work.

Pull-up control FAQ

When should I enable pull-ups?

Enable pull-ups only when the active mode expects them, such as UART RX, HDUART IO, 1-Wire DQ, I2C SDA/SCL or SPI MISO checks. Confirm the target can tolerate the pull-up level first.

When should I disable pull-ups?

Disable them when the target already provides proper biasing, when the line is analog, or when the added pull-up changes the behavior you are trying to observe.

When are pull-ups part of the bench setup rather than the command?

Treat pull-ups as part of the electrical setup whenever bus length, speed, device count or voltage level matters. The firmware shortcut is convenient, but the circuit still decides signal quality.

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