button_event_handler not working properly?

Question

Custom Board which has NordicSemi nRF51822-QFAA (QFAAH0, Rev. 3) MCU, 
 
 The board follows the internal LDO setup. 
 (Ref. nRF51822_PS v3.1 Section 11.3.1) 
 
 
 Softdevice S110 7.1 
 
 
 SDK 7.2 using nrf51-ble-app-temp example ( link provided by Hung Bui ) 
 
 
 I added LED and button initializing codes. 
 
 
 IAR for ARM 7.1 
 
 
 Testing with iPhone 5S, 6 and iPad air (iOS 8.3) 
 / Nexus 5 and Galaxy Note 3 (Android 4.4.2). 
 
 
 Using J-Link Debugger 
 
 
 /****************************************************/ 
 The scheduler, timers, and BLE settings are all fine. 
 My problem is that the button init doesn't work properly. 
 
 I modified the code in order to divide into files. I don't use the bsp functions. 
 
 It seems okay at here. However, after calling any functions, 
 (in this example, after calling timers_start) the mp_buttons become corrupted. 
 (calling leds_ok didn't changed mp_buttons.) 
 
 So, when I press the button, 
 it does call detection_delay_timeout_handler in app_button.c 
 However, it doesn't jumps to the button_event_handler. 
 
 Other parts works well. (The timer interrupts, hrs handling, beacon advertising, and etc.) 
 What could be the reason for the mp_buttons to become corrupted? 
 What settings did I missed? 
 The compiler optimization level is "low". 
 Also, I use the scheduler. 
 I also tried the bsp_init. Although the event handler function pointer was set to null 
 err_code = bsp_init(BSP_INIT_LED | BSP_INIT_BUTTONS,
 APP_TIMER_TICKS(100, APP_TIMER_PRESCALER),
 NULL);
 
 in this case, the values of mp_buttons didn't change when the program counter changes. 
 Plus, when a button is pressed, the program jumps to bsp_button_event_handler. 
 static void bsp_button_event_handler(uint8_t pin_no, uint8_t button_action)
 
 (Although, it doesn't call any functions since the parameter was NULL) 
 When the program counter comes here, the values of mp_buttons were valid as I configured. 
 -Regards

MANGO · Accepted Answer

Holy cow, I made a terrible mistake. Sorry T.T. 
 The problem occurred due to the pointer reference of mp_buttons . 
 
 This was the default setting of the Stack size. 
 
 == Situation : if buttons[] is local variable == 
 (I divided source codes into several .c files. 
 The main function and buttons_init function is located at different .c files.) 
 After the buttons_init function was called, mp_buttons were set. 
 
 As you see, mp_button is referencing memory 0x20003168 . 
 However, as I wrote at the question, after calling any functions, this value changes. 
 
 At the CStack, the location of 0x20003168 is now changed 
 because I declared the buttons[] as a local variable and now it has different values. (D'oh!!) 
 
 
 I didn't thought that mp_buttons will use referencing. 
 I just guessed (without looking the code...) 
 app_button_init will call memcpy or etc to copy the values. 
 So the problem is solved by declaring the buttons[] as a static variable or global variable . 
 Sorry for this mess... I should have thought more. 
 -Regards