Pull-up or Pull-down

In electronic logic circuits, a pull-up resistor or pull-down resistor is a resistor used to ensure a known state for a signal (wiki).

• Pull-up – this option enables the internal pull-up resistor. For GPIO inputs, it means that the pressed state is the LOW signal (connected to the ground).
• Pull-down – For GPIO inputs, it means that the pressed state is the HIGH signal (connected to +3.3V via a 4700 Ohm resistor). You cannot mix internal pull-up or pull-down resistors on the same port.
• External pull-up – similar to the internal pull-up resistor, but you should add it externally on your PCB. It is the main disadvantage. The main advantage, you may mix different pull-up or pull-down types on the same port. A typical resistor value is 4700 Ohm.
• External pull-down – see notes above.

What should you select? It depends on your application and a used external sensor. For GPIO inputs, I prefer “pull-up.” For external sensors, you should look at the sensor’s data sheet for recommended schematics.

Note (CC2530, CC2531): The internal pull-up or pull-down option enabled for one pin automatically selects the same mode for all other pins on the same port P0x, P1x, or P2x. It is the main disadvantage because if you, for example, enable the internal resistor on P0.1, you enable it on P0.2 – P0.7. Therefore, it adds limits for mixing different sensors on the same port.

Note (CC2530, CC2531): P10 and P11 pins do not have internal pull-up resistors. Pull-up or pull-down mode does not affect it. I recommend using an external pull-up or external pull-down mode.

GPIO inputs

Inversed – By default, the firmware interprets the LOW state on the input pin as a button’s pressed state. If this option is enabled, the HIGH state means the pressed button. This option work in junction with the pull mode. For example, if you select the pull-down mode and set the “inversed” option, the logic is twice inverted, the firmware will interpret the LOW state on the input as a button’s pressed state.

Link – The input immediately controls the linked output state (e.g., Input 1 – Output 1). The device sends the on/off state of the output to a coordinator. Otherwise, the input is independent.

Long – The firmware detects and reports to the coordinator a long click (2000 ms). The firmware also sends the release event when a button is unpressed.

Double – The firmware detects and reports a double click (max 500 ms between clicks).

Triple – The firmware detects and reports a triple-click (max 500 ms between clicks).

Switch – an input works as a switch. Only ON (pushed) / OFF (released) states. This option works if the input is linked to the corresponding output. When the switch changes a state, the firmware immediately reports a state of the output. The output can be virtual and assigned to any unused pin.

Switch is On & Link is Off – in this mode, the firmware reports click and release events for an input, also for fast clicks.

Toggle – this option appears for the switch input. The switch works like a toggle button. But because the ON/OFF state can be changed via external commands, a physical button position may differ from an output state.

Bind command – the device sends a click event as this Zigbee command to a bound device, if any. It does not change behavior of internal events and a linked output.

Note: Input 1, if defined as a click button, also acts as a system button and allows you to reset the device if you press and hold that button for 10 seconds. After resetting, the device starts a paring process.

Zigbee cluster: ZCL_CLUSTER_ID_GEN_MULTISTATE_INPUT_BASIC
Zigbee attribute: ATTRID_IOV_BASIC_PRESENT_VALUE
Data type: UINT8 (0 - button released, 1 - single click, 2 - double click, 3 - triple click, 4 - long press (more than 1500 ms))

External wake-up

This is the special GPIO input type. It does not send any button events to a coordinator, but it initiates an extra periodic report, when the device sends a state of all GPIO outputs and measured values from all sensors. Furthermore, if “External wake-up” is configured on Input #1, it works as a pairing button.

GPIO outputs

Inversed – By default, the firmware sets the output pin to HIGH when a logical state is ON. You may invert that logic using this option.

Remember state – The firmware saves the output state to NVRAM and restores it after power off/on. Furthermore, this option works for some sensors (counter, PWM)

Role – this options allows you to specify a role of the corresponding output. The configurator uses this option only when creates a custom converter for Z2M. As a result, the output may have a different icon and associated actions in a frontend or Home Assistant.

Zigbee cluster: ZCL_CLUSTER_ID_GEN_ON_OFF
Zigbee attribute: ATTRID_ON_OFF

Virtual pins

The firmware adds a set of virtual pins:

• CC253x: from P30 to P37
• CC2652, CC1352: from P40 to P47

These pins do not exist in the chip, but you may use them in your configuration. For example, when you need to link an input and a virtual output, add a group switch or signal level control.

Zigbee2MQTT commands

on/off – sets the output to the HIGH or LOW state.

Topic: zigbee2mqtt/[friedly_name]/[channel]/set
Channel: l1, l2, l3 … l16
Payload: ON or OFF

read – gets the current state of a GPIO output.

Topic: zigbee2mqtt/[friedly_name]/[channel]/get/state
Channel: l1, l2, l3 ... l16
Returns the channel state: {"state_[channel]": "ON"}

trigger – sets the output to the HIGH state for N milliseconds, then resets to LOW. Please note, in the PSM mode the rigger may work unexpectedly with long intervals because the chip will go to the sleep mode and stop checking the timer. If you use the “Poll for queued commands” expert option, the trigger interval may be a multiple of this interval.

Topic: zigbee2mqtt/[friedly_name]/[channel]/set
Channel: l1, l2, l3 … l16
Payload: {"trigger": 5000}

interval – sets the periodic reporting interval output to N seconds. This command can be sent to any configured channel, but it will change the interval for all channels at once. The value of 0 or 65535 disables periodic reports.

Topic: zigbee2mqtt/[friedly_name]/[channel]/set
Channel: l1, l2, l3 … l16
Payload: {"interval": 50}