lint: fix unassignedVariable warnings in stm32f1

cpu/stm32f1/periph/i2c.c

@@ -33,7 +33,7 @@
 #include "debug.h"
 
 /* guard file in case no I2C device is defined */
-#if I2C_NUMOF
+#if I2C_0_EN
 
 /* static function definitions */
 static void _start(I2C_TypeDef *dev, uint8_t address, uint8_t rw_flag);
@@ -392,4 +392,4 @@ static inline void _stop(I2C_TypeDef *dev)
     dev->CR1 |= I2C_CR1_STOP;
 }
 
-#endif /* I2C_NUMOF */
+#endif /* I2C_0_EN */

cpu/stm32f1/periph/spi.c

@@ -29,7 +29,7 @@
 #include "debug.h"
 
 /* guard file in case no SPI device is defined */
-#if SPI_NUMOF
+#if SPI_0_EN
 
 int spi_init_master(spi_t dev, spi_conf_t conf, spi_speed_t speed)
 {
@@ -231,4 +231,4 @@ void spi_poweroff(spi_t dev)
     }
 }
 
-#endif /* SPI_NUMOF */
+#endif /* SPI_0_EN */

cpu/stm32f1/periph/timer.c

@@ -31,6 +31,8 @@
 #define ENABLE_DEBUG (0)
 #include "debug.h"
 
+/* guard file in case no TIMER device is defined */
+#if TIMER_0_EN || TIMER_1_EN
 
 static inline void irq_handler(tim_t timer, TIM_TypeDef *dev0, TIM_TypeDef *dev1);
 
@@ -119,8 +121,8 @@ int timer_set(tim_t dev, int channel, unsigned int timeout)
 
 int timer_set_absolute(tim_t dev, int channel, unsigned int value)
 {
-    TIM_TypeDef *timer0 = NULL;
-    TIM_TypeDef *timer1 = NULL;
+    TIM_TypeDef *timer0;
+    TIM_TypeDef *timer1;
 
     switch (dev) {
 #if TIMER_0_EN
@@ -406,3 +408,4 @@ static inline void irq_handler(tim_t timer, TIM_TypeDef *dev0, TIM_TypeDef *dev1
         thread_yield();
     }
 }
+#endif /* TIMER_0_EN || TIMER_1_EN */

cpu/stm32f1/periph/uart.c

@@ -29,6 +29,9 @@
 #include "sched.h"
 #include "thread.h"
 
+/* guard file in case no UART device is defined */
+#if UART_0_EN || UART_1_EN
+
 /**
  * @brief Each UART device has to store two callbacks.
  */