don't turn on gps unless we actually need it

src/main.rs

@@ -40,7 +40,7 @@ mod app {
     use usb_device::prelude::*;
 
     use crate::{
-        config::{Config, GpsSetting, Maybe},
+        config::{Config, GpsSetting, Maybe, MaybeBlackHole},
         gps::{GpsModule, GpsPos},
         radio::RadioManager,
         shell::Shell,
@@ -156,6 +156,7 @@ mod app {
 
         // Setup GPS power
         let mut gps_enable = gpioc.pc8.into_open_drain_output();
+        gps_enable.set_high(); // disable
 
         // Setup GPS serial
         let pins = (gpioa.pa2, gpioa.pa3);
@@ -214,7 +215,13 @@ mod app {
             Status::TxDisabled(false)
         } else {
             green.set_high();
-            gps_enable.set_low(); // enable GPS
+
+            if config.enable_transmit
+                && (matches!(config.black_hole, MaybeBlackHole::Some(_))
+                    || matches!(config.gps, GpsSetting::Receiver))
+            {
+                gps_enable.set_low(); // enable GPS
+            }
 
             Status::Normal
         };