Exception (0) with GPIO interrupts (during WiFi.begin())

[an-erd]

Basic Infos

Hardware

Hardware: Feather Huzzah esp8266
Core Version: 2.4.0-rc1

Description

Exception (0) when using WiFIMulti.run() and GPIO interrupts.
In my code, the ISR (put in RAM) essentially does a comparison of last time called (for debouncing) using millis() and reading with digitalRead() and some comparisons. If the code is close to WiFi.begin(), the problem can be reproduced pretty easy by turning the attached rotary encoder.

The same problem occurs with just using WiFi.begin(), but than is harder to reproduce.

void ICACHE_RAM_ATTR ROTENC::isrInt0() {
	if (millis() - int0_time_ < THRESHOLD)
		return;
	int0_history_ = int0_signal_;
	int0_signal_ = digitalRead(ENCODER_PIN_A);
	if (int0_history_ == int0_signal_)
		return;
	int0_time_ = millis();
	if (int0_signal_ == int1_signal_) {
		rotary_half_steps_--;
	}
	else {
		rotary_half_steps_++;
	}

	changed_halfSteps_ = true;
}

Debug Messages

Exception (0):
epc1=0x40214624 epc2=0x00000000 epc3=0x00000000 excvaddr=0x00000000 depc=0x00000000

ctx: cont 
sp: 3fff1ec0 end: 3fff2450 offset: 01a0

>>>stack>>>
3fff2060:  40106556 40100823 00000000 3ffeed50  
3fff2070:  20017035 00000000 00000002 40100ec2  
3fff2080:  00000000 00000000 0000001f 00000022  
3fff2090:  3fffc200 4010651c 3fffc258 4000050c  
3fff20a0:  400043e6 00000030 00000016 ffffffff  
3fff20b0:  400044ab 3fffc718 3fff21a0 08000000  
3fff20c0:  60000200 08000000 08000000 00000000  
3fff20d0:  0000ffff 00042035 00002035 003fe000  
3fff20e0:  4024dfe0 00000494 003fe000 00000030  
3fff20f0:  00000000 3fff21b1 3fff2120 401049ed  
3fff2100:  4000050c 4010651c 3fffc258 4010664e  
3fff2110:  4021c0fc 3fff2210 3fff0c70 40106343  
3fff2120:  00000075 3fff122c 00000015 60000318  
3fff2130:  3ffe82f8 00000006 00000000 40216c47  
3fff2140:  3fff21b3 3ffe9591 80000000 40214636  
3fff2150:  401065c1 3ffe8778 60000314 401065a8  
3fff2160:  00000002 4000444e 3fff2210 4021c3a4  
3fff2170:  00000000 4000422e 60000200 3fff2220  
3fff2180:  00000000 4000444e 00000100 003ff000  
3fff2190:  00000002 401052a3 00000001 60000200  
3fff21a0:  00000002 4000410f 00001001 00000205  
3fff21b0:  3fffc718 40004a3c 000003fe 4024dfe0  
3fff21c0:  3fffc718 40105514 000003fe 401068dc  
3fff21d0:  000003fe 402410a0 000003ff 40241089  
3fff21e0:  3fff475c 40241173 3fff42c4 00000494  
3fff21f0:  000003fd 00000004 3fff42c4 40241156  
3fff2200:  ffffff01 55aa55aa 0000000f 00000020  
3fff2210:  00000020 00000033 00000033 aa55aa55  
3fff2220:  000003ff 402414a5 00000001 3fff42c4  
3fff2230:  3fff238c bc2c58a4 00000000 40241458  
3fff2240:  40207b6d 3fff3cac 3fff33a4 40207aa3  
3fff2250:  00000000 00000000 00000001 402101bc  
3fff2260:  3fff1130 3fff0ad0 00000000 402100e9  
3fff2270:  3fff1100 3fff0ad0 3fff0c18 4020f428  
3fff2280:  000003e8 00000068 0000ab1d 0000003a  
3fff2290:  3fff23e0 3fff23e0 3fff102c ffffffb3  
3fff22a0:  40240dc2 3fff0ad0 3fff0ce4 00000001  
3fff22b0:  6b08ec00 573aae8a 3f003231 40214b3a  
3fff22c0:  4649575b 30205d49 35353030 3a343739  
3fff22d0:  6e6f4320 4563656e 48366f59 52713476  
3fff22e0:  3150374f 4170534a 48435a71 56477636  
3fff22f0:  7a774850 4f57526e 49494944 31646864  
3fff2300:  656b4270 69594357 6e6b3065 4f703162  
3fff2310:  32743951 01006363 8a6b08ec 00003aae  
3fff2320:  00000001 3fff0ad0 00000001 3fff33a4  
3fff2330:  3ffe953c 00000051 3fff2310 00000000  
3fff2340:  3fff2498 3fff33a4 3fff0ad0 40207c08  
3fff2350:  3fff2498 3fff33a4 3fff0ad0 40207423  
3fff2360:  0000008a 000000ae 0000003a 3fff33a4  
3fff2370:  00000001 ffffffbc 0000002a 40210274  
3fff2380:  00000000 00000000 00000000 8a6b08ec  
3fff2390:  00003aae 00000001 3fff3264 ffffffbb  
3fff23a0:  3fff0400 3fff0ad0 3fff102c 0000001f  
3fff23b0:  ffffffbc 3fff3cac 3fff3cac 00000001  
3fff23c0:  3fff0cd8 00000000 00000002 00000001  
3fff23d0:  3fff2380 00000000 3fff049c bf246000  
3fff23e0:  bd6c0000 3f3d4000 bf246000 3fff1130  
3fff23f0:  3fffdad0 3fff0e58 3fff0ce4 4021103a  
3fff2400:  3fff087c 00000000 3fff0cd6 402110b1  
3fff2410:  3fffdad0 3fff102c 3fff0ce4 4020512a  
3fff2420:  00000000 00000000 00000001 3fff141c  
3fff2430:  3fffdad0 00000000 3fff1414 402142bc  
3fff2440:  feefeffe feefeffe 3fff1430 4010070c  
<<<stack<<<

 ets Jan  8 2013,rst cause:2, boot mode:(1,1)

 
Decoding 49 results
0x40106556: interrupt_handler at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\cores\esp8266/core_esp8266_wiring_digital.c line 128
0x40100823: ppProcessTxQ at ?? line ?
0x40100ec2: pp_post at ?? line ?
0x4010651c: interrupt_handler at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\cores\esp8266/core_esp8266_wiring_digital.c line 122
0x4024dfe0: sleep_reset_analog_rtcreg_8266 at ?? line ?
0x401049ed: ets_timer_disarm at ?? line ?
0x4010651c: interrupt_handler at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\cores\esp8266/core_esp8266_wiring_digital.c line 122
0x4010664e: __digitalRead at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\cores\esp8266/core_esp8266_wiring_digital.c line 95
0x4021c0fc: __ssputs_r at /Users/igrokhotkov/e/newlib-xtensa/xtensa-lx106-elf/newlib/libc/stdio/../../../.././newlib/libc/stdio/nano-vfprintf.c line 180
0x40106343: BUTTON::isrInt0() at C:\Users\AKAEM\AppData\Local\Temp\VMBuilds\spBox\esp8266com_huzzah\Release/button.cpp line 63
0x40216c47: std::_Function_handler    (BUTTON*)> >::_M_invoke(std::_Any_data const&) at c:\users\akaem\documents\arduino\hardware\esp8266com\esp8266\tools\xtensa-lx106-elf\xtensa-lx106-elf\include\c++\4.8.2/functional line 2073
0x40214636: interruptFunctional(void*) at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\cores\esp8266/FunctionalInterrupt.cpp line 18
0x401065c1: interrupt_handler at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\cores\esp8266/core_esp8266_wiring_digital.c line 151
0x401065a8: interrupt_handler at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\cores\esp8266/core_esp8266_wiring_digital.c line 141
0x4021c3a4: _svfprintf_r at /Users/igrokhotkov/e/newlib-xtensa/xtensa-lx106-elf/newlib/libc/stdio/../../../.././newlib/libc/stdio/nano-vfprintf.c line 531
0x401052a3: flash_gd25q32c_read_status at ?? line ?
0x4024dfe0: sleep_reset_analog_rtcreg_8266 at ?? line ?
0x40105514: spi_flash_erase_sector at ?? line ?
0x401068dc: pvPortZalloc at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\cores\esp8266/heap.c line 68
0x402410a0: wifi_param_save_protect_with_check at ?? line ?
0x40241089: wifi_param_save_protect_with_check at ?? line ?
0x40241173: system_param_save_with_protect at ?? line ?
0x40241156: system_param_save_with_protect at ?? line ?
0x402414a5: wifi_station_ap_number_set at ?? line ?
0x40241458: wifi_station_ap_number_set at ?? line ?
0x40207b6d: ESP8266WiFiSTAClass::begin(char const*, char const*, int, unsigned char const*, bool) at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\libraries\ESP8266WiFi\src/ESP8266WiFiSTA.cpp line 516
0x40207aa3: ESP8266WiFiSTAClass::begin(char const*, char const*, int, unsigned char const*, bool) at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\libraries\ESP8266WiFi\src/ESP8266WiFiSTA.cpp line 516
0x402101bc: TwoWire::requestFrom(unsigned char, unsigned int, bool) at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\libraries\Wire/Wire.cpp line 252
0x402100e9: TwoWire::available() at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\libraries\Wire/Wire.cpp line 252
0x4020f428: I2Cdev::readBytes(unsigned char, unsigned char, unsigned char, unsigned char*, unsigned short) at C:\Users\AKAEM\Documents\Arduino\libraries\I2Cdev/I2Cdev.cpp line 148
0x40240dc2: wifi_get_opmode at ?? line ?
0x40214b3a: Print::printf(char const*, ...) at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\cores\esp8266/Print.cpp line 211
0x40207c08: ESP8266WiFiSTAClass::begin(char*, char*, int, unsigned char const*, bool) at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\libraries\ESP8266WiFi\src/ESP8266WiFiSTA.cpp line 516
0x40207423: ESP8266WiFiMulti::run(WifiAPProfile_t) at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\libraries\ESP8266WiFi\src/ESP8266WiFiMulti.cpp line 124
0x40210274: TwoWire::endTransmission() at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\libraries\Wire/Wire.cpp line 252
0x4021103a: SPBOX_COM::enableWlan() at C:\Users\AKAEM\AppData\Local\Temp\VMBuilds\spBox\esp8266com_huzzah\Release/spbox_com.cpp line 234
0x402110b1: SPBOX_COM::checkWlan() at C:\Users\AKAEM\AppData\Local\Temp\VMBuilds\spBox\esp8266com_huzzah\Release/spbox_com.cpp line 234
0x4020512a: loop at C:\Users\AKAEM\AppData\Local\Temp\VMBuilds\spBox\esp8266com_huzzah\Release/spBox.cpp line 1419
0x402142bc: loop_wrapper at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\cores\esp8266/core_esp8266_main.cpp line 57
0x4010070c: cont_norm at C:\Users\AKAEM\Documents\Arduino\hardware\esp8266com\esp8266\cores\esp8266/cont.S line 109

I'm lost in where to continue debugging my code and any hints are appreciated!

Thanks Andreas

[igrr]

Can you see what is the output of xtensa-lx106-elf-addr2line -pfia -e path/to/build/directory/your-sketch.elf 0x40214624?

[an-erd]

Since I'm not at home I needed to recompile on a different PC, and checked with a couple of addresses. They correspond with the stack trace above.

Result of the command above for the given address 0x40214624:

C:\Users\andrerdm\Source\Repos\spBox\spBox\spBox\Release>C:\Users\andrerdm\Docum
ents\Arduino\hardware\esp8266com\esp8266\tools\xtensa-lx106-elf\bin\xtensa-lx106
-elf-addr2line.exe -pfia -e C:\Users\andrerdm\Source\Repos\spBox\spBox\spBox\Rel
ease\spBox.ino.elf 0x40214624
0x40214624: _ZN10MD5Builder8getCharsEPc at C:\Users\andrerdm\Documents\Arduino\h
ardware\esp8266com\esp8266\cores\esp8266/MD5Builder.cpp:84 (discriminator 2)

[igrr]

Unless you are actually calling MD5Builder functions somewhere from an interrupt, this is likely caused by the fact that your ELF file compiled on another PC is slightly different from the one which was used to obtain the stack trace.

The ELF file needs to be exactly the same one as was used for programming the board. Alternatively, recompile and flash the new one. When exception happens, take epc1 value reported in the exception output and feed it into addr2line.

[an-erd]

Thanks for the excellent hint to use xtensa-lx106-elf-addr2line.exe . I was not aware of the tool. It would be great to add a link to this tool to the documentation, FAQ, etc. Finally it then took me 5 minutes to find the reason.

Actually the problem was caused by using the functional interrupt (pull request Functional Interrupts #2745). Removing and going back to an simple isr wrapper function solved my problem.

If it is of interest, I will spend some time with my setup to better understand the issue.

Thanks Andreas