# Displays

## SSD1306 Display (Heltec SX127X and LILYGO® LoRa32 boards)
Several options are available for the display of information on the SSD1306 display. Some options are exclusive to each other, and when a different option is enabled, the current option is disabled.

The current SSD1306 display states are being published to the `SSD1306toMQTT` topic, e.g.

`{"onstate":true,"brightness":50,"display-metric":true,"display-flip":true,"idlelogo":true,"log-oled":false,"json-oled":true}`

### Display ON/OFF
To turn the SSD1306 display on or off.

This can be enabled with the compiler directive `-DDISPLAY_STATE=true`.

MQTT Display OFF command:

`mosquitto_pub -t home/OpenMQTTGateway/commands/MQTTtoSSD1306/config -m {"onstate":false}`

MQTT Display ON command:

`mosquitto_pub -t home/OpenMQTTGateway/commands/MQTTtoSSD1306/config -m {"onstate":true}`

### Brightness
The display brightness can be set between 0-100%.

It is recommended to set a value lower than 100 to extend the life of the OLED display. The default setting is 50.

This can be set with the compiler directive `-DDISPLAY_BRIGHTNESS=50`.

or with the runtime command

`mosquitto_pub -t home/OpenMQTTGateway/commands/MQTTtoSSD1306/config -m {"brightness":50}`

### Metric or Imperial property units
To have applicable device properties displayed in Imperial units, e.g. °F for temperature.

This can be set with the compiler directive `-DDISPLAY_METRIC=false`.

or with the runtime command

`mosquitto_pub -t home/OpenMQTTGateway/commands/MQTTtoSSD1306/config -m {"display-metric":false}`

### Rotating the display by 180 degrees

This can be set with the compiler directive `-DDISPLAY_FLIP=false`.

or with the runtime command

`mosquitto_pub -t home/OpenMQTTGateway/commands/MQTTtoSSD1306/config -m {"display-flip":false}`

### Display idle Logo
To display the OpenMQTTGateway logo during device display idle time. This reduces the likelihood of burn-in.

This can be set with the compiler directive `-DDISPLAY_IDLE_LOGO=true`.

or at runtime with

`mosquitto_pub -t home/OpenMQTTGateway/commands/MQTTtoSSD1306/config -m {"idlelogo":true}`

### Setting the log output

The display of serial log messages to the display can be enabled via compiler directive `-DLOG_TO_OLED=true` or via MQTT commands.

For example if you want to set the serial log to OLED

`mosquitto_pub -t home/OpenMQTTGateway/commands/MQTTtoSSD1306/config -m '{"log-oled":true}'`

you can also revert it back with

`mosquitto_pub -t home/OpenMQTTGateway/commands/MQTTtoSSD1306/config -m '{"log-oled":false}'`

The log level of the messages displayed is Errors and Warnings, and this can only be changed via the compiler directive `-DLOG_LEVEL_OLED=LOG_LEVEL_NOTICE`.  

### Displaying Module json messages (default)

The display of messages from various modules is also supported. Currently supported modules include `ZgatewayRTL_433`, `ZgatewayBT` and `ZsensorBME280`.

This can be enabled with the compiler directive `-DJSON_TO_OLED=true`.

You can also change it by MQTT. For example if you want to display module json messages:

`mosquitto_pub -t home/OpenMQTTGateway/commands/MQTTtoSSD1306/config -m '{"json-oled":true}'`

And to disable the display of module json messages:

`mosquitto_pub -t home/OpenMQTTGateway/commands/MQTTtoSSD1306/config -m '{"display-json":false}'`