diff --git a/ch32v-insert-coin/src/app.rs b/ch32v-insert-coin/src/app.rs
index fbd2ddc..4cc0dd7 100644
--- a/ch32v-insert-coin/src/app.rs
+++ b/ch32v-insert-coin/src/app.rs
@@ -389,8 +389,12 @@ impl App {
         }
         if self.timers.batt_adc_timer.need_service() {
             self.timers.batt_adc_timer.service();
+            let bv = self.interfaces.adc_core.get_battery_voltage();
             #[cfg(feature = "enable_print")]
-            println!("batt adc service");
+            println!("batt adc service: {bv}");
+
+            // TODO:
+            // do stuff if the battery voltage is below some threshold
         }
         if self.timers.usb_adc_timer.need_service() {
             self.timers.usb_adc_timer.service();