blackpill-f4: Extract macros for VTRef pin and channel

Author: ALTracer

src/platforms/common/blackpill-f4/blackpill-f4.c

@@ -162,16 +162,16 @@ bool platform_nrst_get_val(void)
 static void adc_init(void)
 {
 	rcc_periph_clock_enable(RCC_ADC1);
-	gpio_mode_setup(GPIOA, GPIO_MODE_ANALOG, GPIO_PUPD_NONE, GPIO0);
+	gpio_mode_setup(VTREF_PORT, GPIO_MODE_ANALOG, GPIO_PUPD_NONE, VTREF_PIN);
 	adc_power_off(ADC1);
 	adc_disable_scan_mode(ADC1);
-	adc_set_sample_time(ADC1, ADC_CHANNEL0, ADC_SMPR_SMP_480CYC);
+	adc_set_sample_time(ADC1, VTREF_CHANNEL, ADC_SMPR_SMP_480CYC);
 	adc_power_on(ADC1);
 }
 
 static uint16_t platform_adc_read(void)
 {
-	const uint8_t channel = ADC_CHANNEL0;
+	const uint8_t channel = VTREF_CHANNEL;
 	adc_set_regular_sequence(ADC1, 1, &channel);
 	adc_start_conversion_regular(ADC1);
 	while (!adc_eoc(ADC1))

src/platforms/common/blackpill-f4/blackpill-f4.h

@@ -196,6 +196,10 @@ extern bool debug_bmp;
 #define OB_SPI_CS_PORT GPIOA
 #define OB_SPI_CS      GPIO4
 
+#define VTREF_PORT    GPIOB
+#define VTREF_PIN     GPIO0
+#define VTREF_CHANNEL ADC_CHANNEL8
+
 /* USART2 with PA2 and PA3 is selected as USBUSART. Alternatively USART1 with PB6 and PB7 can be used. */
 #define USBUSART               USBUSART2
 #define USBUSART_CR1           USBUSART2_CR1