stm32_common:board_hw_rev_ver Use Analog resistor detection

When the VER_DRIVE and REV_DRIVE are the same GPIO
   we need to use Analog detection.

platforms/nuttx/src/px4/stm/stm32_common/board_hw_info/board_hw_rev_ver.c

@@ -151,6 +151,7 @@ static int read_id_dn(int *id, uint32_t gpio_drive, uint32_t gpio_sense, int adc
 {
 	int rv = -EIO;
 	const unsigned int samples  = 16;
+#if GPIO_HW_REV_DRIVE != GPIO_HW_VER_DRIVE
 	/*
 	 * Step one is there resistors?
 	 *
@@ -206,7 +207,6 @@ static int read_id_dn(int *id, uint32_t gpio_drive, uint32_t gpio_sense, int adc
 
 	if ((high ^ low) && low == 0) {
 
-
 		/* Yes - Fire up the ADC (it has once control) */
 
 		if (px4_arch_adc_init(HW_REV_VER_ADC_BASE) == OK) {
@@ -235,12 +235,102 @@ static int read_id_dn(int *id, uint32_t gpio_drive, uint32_t gpio_sense, int adc
 		rv = OK;
 	}
 
+#else /* GPIO_HW_REV_DRIVE == GPIO_HW_VER_DRIVE */
+
+	/*
+	 * Step one is there resistors?
+	 *
+	 * With the common REV/VER Drive we have to look at the ADC values.
+	 * to determine if the R's are hooked up. This is because the
+	 * the REV and VER pairs will influence each other and not make
+	 * digital thresholds.
+	 *
+	 * I.E
+	 *
+	 *     VDD
+	 *     442K
+	 *       REV is a Float
+	 *     24.9K
+	 *        Drive as input
+	 *     442K
+	 *       VER is 0.
+	 *     24.9K
+	 *     VDD
+	 *
+	 *   This is 466K up and 442K down.
+	 *
+	 *  Driving VER Low and reading DRIVE will result in approximately mid point
+	 *  values not a digital Low.
+	 */
+
+	uint32_t dn_sum = 0;
+	uint16_t dn = 0;
+	uint16_t high = 0;
+	uint16_t low = 0;
+
 	/*  Turn the drive lines to digital outputs High */
 
 	stm32_configgpio(gpio_drive);
-	return rv;
+
+	up_udelay(100); /* About 10 TC assuming 485 K */
+
+	for (unsigned av = 0; av < samples; av++) {
+		if (px4_arch_adc_init(HW_REV_VER_ADC_BASE) == OK) {
+			dn = px4_arch_adc_sample(HW_REV_VER_ADC_BASE, adc_channel);
+
+			if (dn == 0xffff) {
+				break;
 			}
 
+			dn_sum  += dn;
+		}
+	}
+
+	if (dn != 0xffff) {
+		high = dn_sum / samples;
+	}
+
+	/*  Turn the drive lines to digital outputs LOW */
+
+	stm32_configgpio(gpio_drive ^ GPIO_OUTPUT_SET);
+
+	up_udelay(100); /* About 10 TC assuming 485 K */
+
+	dn_sum = 0;
+
+	for (unsigned av = 0; av < samples; av++) {
+
+		dn = px4_arch_adc_sample(HW_REV_VER_ADC_BASE, adc_channel);
+
+		if (dn == 0xffff) {
+			break;
+		}
+
+		dn_sum  += dn;
+	}
+
+	if (dn != 0xffff) {
+		low = dn_sum / samples;
+	}
+
+	if ((high > low) && high > px4_arch_adc_dn_fullcount() - 100) {
+
+		*id = low;
+		rv = OK;
+
+	} else {
+		/* No - No Resistors is ID 0 */
+		*id = 0;
+		rv = OK;
+	}
+
+#endif /* GPIO_HW_REV_DRIVE != GPIO_HW_VER_DRIVE */
+
+	/*  Turn the drive lines to digital outputs High */
+
+	stm32_configgpio(gpio_drive);
+	return rv;
+}
 
 static int determine_hw_info(int *revision, int *version)
 {