Fix null dereference, invert auto_brightness to reenable screen

Author: hierophect

ports/stm/boards/meowbit_v121/board.c

@@ -106,7 +106,7 @@ void board_init(void) {
         &pin_PB03,
         NO_BRIGHTNESS_COMMAND,
         1.0f, // brightness (ignored)
-        true, // auto_brightness
+        false, // auto_brightness
         false, // single_byte_bounds
         false, // data_as_commands
         true, // auto_refresh

ports/stm/boards/meowbit_v121/mpconfigboard.mk

@@ -18,4 +18,6 @@ OPTIMIZATION_FLAGS = -Os
 
 LD_COMMON = boards/common_default.ld
 LD_FILE = boards/STM32F401xe_boot.ld
-# LD_FILE = boards/STM32F401xe_fs.ld # use for internal flash
+
+# For debugging - also comment BOOTLOADER_OFFSET and BOARD_VTOR_DEFER
+# LD_FILE = boards/STM32F401xe_fs.ld

ports/stm/common-hal/pulseio/PWMOut.c

@@ -239,13 +239,14 @@ void common_hal_pulseio_pwmout_deinit(pulseio_pwmout_obj_t* self) {
         HAL_TIM_PWM_Stop(&self->handle, self->channel);
     }
     reset_pin_number(self->tim->pin->port,self->tim->pin->number);
-    self->tim = NULL;
 
     //if reserved timer has no active channels, we can disable it
     if (!reserved_tim[self->tim->tim_index - 1]) {
         tim_frequencies[self->tim->tim_index - 1] = 0x00;
         stm_peripherals_timer_free(self->handle.Instance);
     }
+
+    self->tim = NULL;
 }
 
 void common_hal_pulseio_pwmout_set_duty_cycle(pulseio_pwmout_obj_t* self, uint16_t duty) {