add DisplayOff script, which turns off backlight and then stops the display driver - running Soundslab will start it back up.

DisplayOff.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python
+from ST7789 import ST7789
+
+SPI_SPEED_MHZ = 80
+
+st7789 = ST7789(
+    rotation=90,  # Needed to display the right way up on Pirate Audio
+    port=0,       # SPI port
+    cs=1,         # SPI port Chip-select channel
+    dc=9,         # BCM pin used for data/command
+    backlight=13,
+    spi_speed_hz=SPI_SPEED_MHZ * 1000 * 1000
+)
+
+st7789.set_backlight(0)
+st7789.command(0x28)  # DISPOFF