Reduce display startup time

Core/Inc/shorttimer.h

@@ -0,0 +1,28 @@
+#ifndef INC_SHORTTIMER_H
+#define INC_SHORTTIMER_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Timer with an arbitrary period.
+ *
+ * shorttimer_callback() must be called in HAL_TIM_PeriodElapsedCallback.
+ */
+
+#include "stm32h7xx_hal.h"
+
+#include <stdint.h>
+
+void shorttimer_init(TIM_HandleTypeDef *handle);
+
+uint32_t shorttimer_gettick(void);
+void shorttimer_sleep(uint32_t microseconds);
+void shorttimer_callback(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // INC_SHORTTIMER_H