From 553c64925292d0fc99b46d9514eb6646472033e7 Mon Sep 17 00:00:00 2001
From: David Sidrane <david_s5@nscdg.com>
Date: Tue, 18 Jul 2017 17:09:50 -1000
Subject: [PATCH] px4fmu-v2:Init GPIO_VDD_3V3_SENSORS_EN off at reset

  Insure a 0.0 voltage initial condition on VDD_3V3_SENSORS
  By starting the GPIO_VDD_3V3_SENSORS_EN, low and deferring
  the GPIO init of the slave selects and drdy signals until
  board_app_initialize. We get ~ 80 ms of power off time
  with 0.00 voltage applied to the sensors.
---
 src/drivers/boards/px4fmu-v2/board_config.h |  2 +-
 src/drivers/boards/px4fmu-v2/px4fmu2_init.c | 25 ++++++++++++++++++---
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/src/drivers/boards/px4fmu-v2/board_config.h b/src/drivers/boards/px4fmu-v2/board_config.h
index 5eec8fdaf9..99b9d64bcb 100644
--- a/src/drivers/boards/px4fmu-v2/board_config.h
+++ b/src/drivers/boards/px4fmu-v2/board_config.h
@@ -188,7 +188,7 @@
 #define GPIO_VDD_BRICK_VALID	(GPIO_INPUT|GPIO_PULLUP|GPIO_PORTB|GPIO_PIN5)
 #define GPIO_VDD_SERVO_VALID	(GPIO_INPUT|GPIO_PULLUP|GPIO_PORTB|GPIO_PIN7)
 #define GPIO_VDD_USB_VALID		(GPIO_INPUT|GPIO_PULLUP|GPIO_PORTC|GPIO_PIN0)
-#define GPIO_VDD_3V3_SENSORS_EN	(GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_2MHz|GPIO_OUTPUT_SET|GPIO_PORTE|GPIO_PIN3)
+#define GPIO_VDD_3V3_SENSORS_EN	(GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_2MHz|GPIO_OUTPUT_CLEAR|GPIO_PORTE|GPIO_PIN3)
 #define GPIO_VDD_5V_HIPOWER_OC	(GPIO_INPUT|GPIO_PULLUP|GPIO_PORTE|GPIO_PIN10)
 #define GPIO_VDD_5V_PERIPH_OC	(GPIO_INPUT|GPIO_PULLUP|GPIO_PORTE|GPIO_PIN15)
 
diff --git a/src/drivers/boards/px4fmu-v2/px4fmu2_init.c b/src/drivers/boards/px4fmu-v2/px4fmu2_init.c
index 30ac5085b7..6bef348338 100644
--- a/src/drivers/boards/px4fmu-v2/px4fmu2_init.c
+++ b/src/drivers/boards/px4fmu-v2/px4fmu2_init.c
@@ -329,6 +329,10 @@ stm32_boardinitialize(void)
 	/* configure LEDs */
 	board_autoled_initialize();
 
+	/* Start with the Sensor voltage off */
+
+	stm32_configgpio(GPIO_VDD_3V3_SENSORS_EN);
+
 	/* configure ADC pins */
 
 	stm32_configgpio(GPIO_ADC1_IN2);	/* BATT_VOLTAGE_SENS */
@@ -340,7 +344,6 @@ stm32_boardinitialize(void)
 
 	/* configure power supply control/sense pins */
 	stm32_configgpio(GPIO_VDD_5V_PERIPH_EN);
-	stm32_configgpio(GPIO_VDD_3V3_SENSORS_EN);
 	stm32_configgpio(GPIO_VDD_BRICK_VALID);
 	stm32_configgpio(GPIO_VDD_SERVO_VALID);
 	stm32_configgpio(GPIO_VDD_USB_VALID);
@@ -348,8 +351,9 @@ stm32_boardinitialize(void)
 	stm32_configgpio(GPIO_VDD_5V_PERIPH_OC);
 
 
-	/* configure SPI interfaces */
-	stm32_spiinitialize();
+	/* configure SPI interfaces is deferred to board_app_initialize
+	 * to delay the sensor power up with out adding a delay
+	 */
 
 }
 
@@ -385,6 +389,7 @@ static struct sdio_dev_s *sdio;
 
 __EXPORT int board_app_initialize(uintptr_t arg)
 {
+
 #if defined(CONFIG_HAVE_CXX) && defined(CONFIG_HAVE_CXXINITIALIZE)
 
 	/* run C++ ctors before we go any further */
@@ -422,7 +427,21 @@ __EXPORT int board_app_initialize(uintptr_t arg)
 
 #endif // BOARD_HAS_SIMPLE_HW_VERSIONING
 
+	/* Bring up the Sensor power */
+
+	stm32_gpiowrite(GPIO_VDD_3V3_SENSORS_EN, 1);
+
+	/* Ensure the power is on 1 ms before we drive the GPIO pins */
+
+	usleep(1000);
+
+	/* Now it is ok to drive the pins high so configure SPI GPIO */
+
+	stm32_spiinitialize();
+
+
 	/* configure the high-resolution time/callout interface */
+
 	hrt_init();
 
 	param_init();