Made a small patch that types battery level to screen if you're connected via bluetooth and hid_listen is unavailable.
Just press LShift+RShift+b and it will automatically type something like "BAT: 3790mV". Could be used for other messages as well.
diff --git a/keyboard/hhkb/rn42/rn42.c b/keyboard/hhkb/rn42/rn42.c
index 710169e..0af0daf 100644
--- a/keyboard/hhkb/rn42/rn42.c
+++ b/keyboard/hhkb/rn42/rn42.c
@@ -235,3 +235,16 @@ static void config_send_keyboard(report_keyboard_t *report) {}
static void config_send_mouse(report_mouse_t *report) {}
static void config_send_system(uint16_t data) {}
static void config_send_consumer(uint16_t data) {}
+
+void rn42_printf(const char * format, ...) {
+ int i;
+ char buf[16];
+ va_list args;
+ va_start(args, format);
+ vsprintf(buf, format, args);
+ va_end(args);
+ for (i=0; i<strlen(buf); i++) {
+ serial_send(buf[i]);
+ }
+}
+
diff --git a/keyboard/hhkb/rn42/rn42.h b/keyboard/hhkb/rn42/rn42.h
index db6916f..9ec0d0c 100644
--- a/keyboard/hhkb/rn42/rn42.h
+++ b/keyboard/hhkb/rn42/rn42.h
@@ -19,5 +19,6 @@ void rn42_cts_hi(void);
void rn42_cts_lo(void);
bool rn42_linked(void);
void rn42_set_leds(uint8_t l);
+void rn42_printf(const char * format, ...);
#endif
diff --git a/keyboard/hhkb/rn42/rn42_task.c b/keyboard/hhkb/rn42/rn42_task.c
index 5107fef..e465eaa 100644
--- a/keyboard/hhkb/rn42/rn42_task.c
+++ b/keyboard/hhkb/rn42/rn42_task.c
@@ -364,6 +364,7 @@ bool command_extra(uint8_t code)
xprintf("%02u:", t/3600);
xprintf("%02u:", t%3600/60);
xprintf("%02u\n", t%60);
+ rn42_printf("BAT: %umV\t", b);
return true;
case KC_U:
if (config_mode) return false;
