add examples

RTL00_SDKV35a/example_sources/gpio_level_irq/readme.txt

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+Example Description
+
+This example describes how to implement high/low level trigger on 1 gpio pin.
+
+Pin name PC_4 and PC_5 map to GPIOC_4 and GPIOC_5:
+Connect PC_4 and PC_5
+ - PC_4 as gpio input high/low level trigger.
+ - PC_5 as gpio output
+
+In this example, PC_5 is signal source that change level to high and low periodically.
+
+PC_4 setup to listen low level events in initial.
+When PC_4 catch low level events, it disable the irq to avoid receiving duplicate events.
+(NOTE: the level events will keep invoked if level keeps in same level)
+
+Then PC_4 is configured to listen high level events and enable irq.
+As PC_4 catches high level events, it changes back to listen low level events.
+
+Thus PC_4 can handle both high/low level events.
+
+In this example, you will see log that prints high/low level event periodically.

RTL00_SDKV35a/example_sources/gpio_level_irq/src/main.c

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+/*
+ *  Routines to access hardware
+ *
+ *  Copyright (c) 2015 Realtek Semiconductor Corp.
+ *
+ *  This module is a confidential and proprietary property of RealTek and
+ *  possession or use of this module requires written permission of RealTek.
+ */
+
+#include "device.h"
+#include "gpio_irq_api.h"   // mbed
+#include "gpio_irq_ex_api.h"
+#include "diag.h"
+#include "main.h"
+
+#define GPIO_IRQ_LEVEL_PIN        PC_4
+#define GPIO_SIGNAL_SOURCE        PC_5
+
+gpio_irq_t gpio_level;
+int current_level = IRQ_LOW;
+
+void gpio_level_irq_handler (uint32_t id, gpio_irq_event event)
+{
+    uint32_t *level = (uint32_t *) id;
+
+    // Disable level irq because the irq will keep triggered when it keeps in same level.
+    gpio_irq_disable(&gpio_level);
+
+    // make some software de-bounce here if the signal source is not stable.
+
+    if (*level == IRQ_LOW )
+    {
+        printf("low level event\r\n");
+
+        // Change to listen to high level event
+        *level = IRQ_HIGH;
+        gpio_irq_set(&gpio_level, IRQ_HIGH, 1);
+        gpio_irq_enable(&gpio_level);
+    }
+    else if (*level == IRQ_HIGH)
+    {
+        printf("high level event\r\n");
+
+        // Change to listen to low level event
+        *level = IRQ_LOW;
+        gpio_irq_set(&gpio_level, IRQ_LOW, 1);
+        gpio_irq_enable(&gpio_level);
+    }
+}
+
+void main(void)
+{
+    int i;
+
+    // configure level trigger handler
+    gpio_irq_init(&gpio_level, GPIO_IRQ_LEVEL_PIN, gpio_level_irq_handler, (uint32_t)(&current_level));
+    gpio_irq_set(&gpio_level, IRQ_LOW, 1);
+    gpio_irq_enable(&gpio_level);
+
+    // configure gpio as signal source for high/low level trigger
+    gpio_t gpio_src;
+    gpio_init(&gpio_src, GPIO_SIGNAL_SOURCE);
+    gpio_dir(&gpio_src, PIN_OUTPUT);    // Direction: Output
+    gpio_mode(&gpio_src, PullNone);
+
+    while(1) {
+        gpio_write(&gpio_src, 1);
+        for (i=0; i<20000000; i++) asm("nop");
+        gpio_write(&gpio_src, 0);
+        for (i=0; i<20000000; i++) asm("nop");
+    }
+}
+