diff --git a/README.i2c-intf b/README.i2c-intf
index eaf7d14..e0cbe92 100644
--- a/README.i2c-intf
+++ b/README.i2c-intf
@@ -45,9 +45,6 @@ General ranges:
 
 0x20: System configuration
    bit 0: disable KB scanning (1: scanning disabled, 0: scanning enabled)
-   bit 1: enable USB debug interface
-          1: enabled
-          0: disabled
 
 0x21: Charger register address
 0x22: Charger register value
diff --git a/firmware/main.c b/firmware/main.c
index aa1fb10..0d7be57 100644
--- a/firmware/main.c
+++ b/firmware/main.c
@@ -1932,6 +1932,9 @@ void main(void)
 		if (jump_to_usb_bootloader)
 			__asm__ ("ljmp _usb_bootloader_jump");
 
+		// get current system config
+		uint8_t cfg = REG_SYS(CONFIG);
+
 		// if the 20ms timer did not expire yet, check if we can
 		// powerdown, otherwise busyloop
 		if (!run_timed_tasks) {
diff --git a/firmware/registers.h b/firmware/registers.h
index 77af737..b5da0e5 100644
--- a/firmware/registers.h
+++ b/firmware/registers.h
@@ -41,7 +41,6 @@
 
 #define REG_SYS_CONFIG		0x20
 #define REG_SYS_CONFIG_SCAN_BLOCK	BIT(0)
-#define REG_SYS_CONFIG_USB_DEBUG_EN	BIT(1)
 
 #define REG_SYS_I2CA_ADDR	0x21
 #define REG_SYS_I2CA_DATA	0x22