A few tweaks

Author: multiplemonomials

platform/source/mbed_board.c

@@ -31,6 +31,7 @@ WEAK MBED_NORETURN void mbed_die(void)
 
 #ifdef LED1
     gpio_t led_err;
+    memset(&led_err, 0, sizeof(gpio_t));
     gpio_init_out(&led_err, LED1);
 #endif
 

targets/TARGET_Ambiq_Micro/TARGET_Apollo3/device/gpio_api.c

@@ -57,7 +57,6 @@ int gpio_is_connected(const gpio_t *obj)
 void gpio_init(gpio_t *obj, PinName pin)
 {
     MBED_ASSERT(obj != NULL);
-    memset(obj, 0, sizeof(gpio_t));
     obj->pad = (ap3_uart_pad_t)pin;
     return;
 }

targets/TARGET_Ambiq_Micro/TARGET_Apollo3/device/objects_gpio.h

@@ -54,9 +54,9 @@ typedef enum {
     PullDown = 1 << 1,
 
     OpenDrain = 1 << 2,
-    OpenDrainPullUp = OpenDrain | PullUp, ///< Open-drain mode with pull up
-    OpenDrainPullDown = OpenDrain | PullDown, ///< Open-drain mode with pull down
-    OpenDrainNoPull = OpenDrain, ///< Open-drain mode with no pullup/pulldown
+    OpenDrainPullUp = OpenDrain | PullUp, ///< Open-drain mode with pull up. Supported on all IOs except IO 20.
+    OpenDrainPullDown = OpenDrain | PullDown, ///< Open-drain mode with pull down. Only supported on IO 20.
+    OpenDrainNoPull = OpenDrain, ///< Open-drain mode with no pullup/pulldown. Supported on all IOs.
 
     PullDefault = PullNone
 } PinMode;