I’m getting nowhere.
How do I stop the compile using a “previously compiled library” ?
I have changed the DCC_Decoder.cpp file but I don’t know whether it is using the modified version.
N.B I have accumulated several (7) copies of DCC_Decoder.cpp & DCC_Decoder.h files over the years, in various Arduino folders, as well as three each of the .o &.d appended versions.
One of the problems I have is after putting the Serial.print(func); into the interrupt routine in DCC_interrupt routine, where do I put the Serial.begin( ); command?
I tried in the DCC_Decoder.cpp and it throws up an error, presumably as there isn’t a void setup(): section.
I put it in the program void setup() section and I just get a continuous output of "1"s whether there is an input on pin 2 of the Xiao or not.
Keith
Serial.begin() goes in Setup(). Serial.println(func); has 2 underscores on either side of func The forum sees fit to strip them. Either put the 4 underscore or just use Serial.println(“This is the message to look for”);
Is pin 2 the same as A2/D2 ?
OP, did you solve this ? Give up on it ? There is no reason what you are trying to do can’t be made to work. Inquiring minds want to know.
Hi
I haven’t given up and hopefully can put some effort in over this weekend. 
As I said previously I have several other things on the go at present, so the amount of time I can spend on this is currently limited to an odd hour here and there, in between other jobs.
Keith
Back on the case
I have now tried Serial.println(func); (with 2 underscores each side of the word “func”) in the DCC_interrupt section of dcc_decoder.cpp.
I have “Serial.begin(9600)” in the void setup() section of the sketch.
I am running the serial monitor but don’t get any output when sending commands to the Xiao.
I changed the Serial.print command to “Serial.println(“This is the message to look for”)”
Still does anything print
You might put the same message at the end of the setup(). put a delay(5000); just to make sure it’s all initialized and make sure the monitor is also set to 9600. If you see that message and not the interrupt message than the chain of neededs are not being met. Data stream on A2/D2 ? Interrupt actually being set to the same pin ? Data stream present and good logic high & low on the Xiao interrupt pin?
A problem
Instead of just uploading modified sketches today I hit accidentally hit “Verify/compile” instead and noticed that the dcc_decoder.cpp file I had been modifying and in the seeed library, was not the one that was being used during the compile.
For some reason the program was ignoring that one and retrieving a unmodified version from a different library.
I changed the names of all the other verions of dcc_decoder.cpp & dcc_decoder.h to force the program to use the ones in the seeed library.
Doing a compile after that threw up errors from the modified dcc_decoder.cpp file:
Using board 'seeed_XIAO_m0' from platform in folder: C:\Users\Keith.DESKTOP-55532Q9\AppData\Local\Arduino15\packages\Seeeduino\hardware\samd\1.8.2
Using core 'arduino' from platform in folder: C:\Users\Keith.DESKTOP-55532Q9\AppData\Local\Arduino15\packages\Seeeduino\hardware\samd\1.8.2
Detecting libraries used...
"C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\arm-none-eabi-gcc\\7-2017q4/bin/arm-none-eabi-g++" -mcpu=cortex-m0plus -mthumb -c -g -Os -w -std=gnu++14 -ffunction-sections -fdata-sections -fno-threadsafe-statics -nostdlib --param max-inline-insns-single=500 -fno-rtti -fno-exceptions "-D__SKETCH_NAME__=\"\"\"Dapol_Signal_Xiao.ino\"\"\"" -w -x c++ -E -CC -DF_CPU=48000000L -DARDUINO=10607 -DARDUINO_SEEED_XIAO_M0 -DARDUINO_ARCH_SAMD -DARDUINO_SAMD_ZERO -D__SAMD21__ -D__SAMD21G18A__ -DARM_MATH_CM0PLUS -DSEEED_XIAO_M0 -DUSB_VID=0x2886 -DUSB_PID=0x802F -DUSBCON -DUSB_CONFIG_POWER=100 "-DUSB_MANUFACTURER=\"Seeed\"" "-DUSB_PRODUCT=\"Seeed XIAO M0\"" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore/tinyusb/src" -DARDUINO_SAMD_ZERO -D__SAMD21__ -D__SAMD21G18A__ -DARM_MATH_CM0PLUS -DSEEED_XIAO_M0 -DUSB_VID=0x2886 -DUSB_PID=0x802F -DUSBCON -DUSB_CONFIG_POWER=100 "-DUSB_MANUFACTURER=\"Seeed\"" "-DUSB_PRODUCT=\"Seeed XIAO M0\"" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore/tinyusb/src" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS\\5.7.0/CMSIS/Core/Include/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS\\5.7.0/CMSIS/DSP/Include/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS-Atmel\\1.2.1/CMSIS-Atmel/CMSIS/Device/ATMEL/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\variants\\XIAO_m0" "C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Temp\\arduino-sketch-E8C477A82A9968D483CF46B123C568F8\\sketch\\Dapol_Signal_Xiao.ino.cpp" -o nul
Alternatives for DCC_Decoder.h: [DCC_Decoder-master@1.6]
ResolveLibrary(DCC_Decoder.h)
-> candidates: [DCC_Decoder-master@1.6]
"C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\arm-none-eabi-gcc\\7-2017q4/bin/arm-none-eabi-g++" -mcpu=cortex-m0plus -mthumb -c -g -Os -w -std=gnu++14 -ffunction-sections -fdata-sections -fno-threadsafe-statics -nostdlib --param max-inline-insns-single=500 -fno-rtti -fno-exceptions "-D__SKETCH_NAME__=\"\"\"Dapol_Signal_Xiao.ino\"\"\"" -w -x c++ -E -CC -DF_CPU=48000000L -DARDUINO=10607 -DARDUINO_SEEED_XIAO_M0 -DARDUINO_ARCH_SAMD -DARDUINO_SAMD_ZERO -D__SAMD21__ -D__SAMD21G18A__ -DARM_MATH_CM0PLUS -DSEEED_XIAO_M0 -DUSB_VID=0x2886 -DUSB_PID=0x802F -DUSBCON -DUSB_CONFIG_POWER=100 "-DUSB_MANUFACTURER=\"Seeed\"" "-DUSB_PRODUCT=\"Seeed XIAO M0\"" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore/tinyusb/src" -DARDUINO_SAMD_ZERO -D__SAMD21__ -D__SAMD21G18A__ -DARM_MATH_CM0PLUS -DSEEED_XIAO_M0 -DUSB_VID=0x2886 -DUSB_PID=0x802F -DUSBCON -DUSB_CONFIG_POWER=100 "-DUSB_MANUFACTURER=\"Seeed\"" "-DUSB_PRODUCT=\"Seeed XIAO M0\"" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore/tinyusb/src" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS\\5.7.0/CMSIS/Core/Include/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS\\5.7.0/CMSIS/DSP/Include/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS-Atmel\\1.2.1/CMSIS-Atmel/CMSIS/Device/ATMEL/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\variants\\XIAO_m0" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\libraries\\DCC_Decoder-master" "C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Temp\\arduino-sketch-E8C477A82A9968D483CF46B123C568F8\\sketch\\Dapol_Signal_Xiao.ino.cpp" -o nul
"C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\arm-none-eabi-gcc\\7-2017q4/bin/arm-none-eabi-g++" -mcpu=cortex-m0plus -mthumb -c -g -Os -w -std=gnu++14 -ffunction-sections -fdata-sections -fno-threadsafe-statics -nostdlib --param max-inline-insns-single=500 -fno-rtti -fno-exceptions "-D__SKETCH_NAME__=\"\"\"Dapol_Signal_Xiao.ino\"\"\"" -w -x c++ -E -CC -DF_CPU=48000000L -DARDUINO=10607 -DARDUINO_SEEED_XIAO_M0 -DARDUINO_ARCH_SAMD -DARDUINO_SAMD_ZERO -D__SAMD21__ -D__SAMD21G18A__ -DARM_MATH_CM0PLUS -DSEEED_XIAO_M0 -DUSB_VID=0x2886 -DUSB_PID=0x802F -DUSBCON -DUSB_CONFIG_POWER=100 "-DUSB_MANUFACTURER=\"Seeed\"" "-DUSB_PRODUCT=\"Seeed XIAO M0\"" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore/tinyusb/src" -DARDUINO_SAMD_ZERO -D__SAMD21__ -D__SAMD21G18A__ -DARM_MATH_CM0PLUS -DSEEED_XIAO_M0 -DUSB_VID=0x2886 -DUSB_PID=0x802F -DUSBCON -DUSB_CONFIG_POWER=100 "-DUSB_MANUFACTURER=\"Seeed\"" "-DUSB_PRODUCT=\"Seeed XIAO M0\"" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore/tinyusb/src" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS\\5.7.0/CMSIS/Core/Include/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS\\5.7.0/CMSIS/DSP/Include/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS-Atmel\\1.2.1/CMSIS-Atmel/CMSIS/Device/ATMEL/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\variants\\XIAO_m0" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\libraries\\DCC_Decoder-master" "C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\libraries\\DCC_Decoder-master\\DCC_Decoder.cpp" -o nul
Generating function prototypes...
"C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\arm-none-eabi-gcc\\7-2017q4/bin/arm-none-eabi-g++" -mcpu=cortex-m0plus -mthumb -c -g -Os -w -std=gnu++14 -ffunction-sections -fdata-sections -fno-threadsafe-statics -nostdlib --param max-inline-insns-single=500 -fno-rtti -fno-exceptions "-D__SKETCH_NAME__=\"\"\"Dapol_Signal_Xiao.ino\"\"\"" -w -x c++ -E -CC -DF_CPU=48000000L -DARDUINO=10607 -DARDUINO_SEEED_XIAO_M0 -DARDUINO_ARCH_SAMD -DARDUINO_SAMD_ZERO -D__SAMD21__ -D__SAMD21G18A__ -DARM_MATH_CM0PLUS -DSEEED_XIAO_M0 -DUSB_VID=0x2886 -DUSB_PID=0x802F -DUSBCON -DUSB_CONFIG_POWER=100 "-DUSB_MANUFACTURER=\"Seeed\"" "-DUSB_PRODUCT=\"Seeed XIAO M0\"" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore/tinyusb/src" -DARDUINO_SAMD_ZERO -D__SAMD21__ -D__SAMD21G18A__ -DARM_MATH_CM0PLUS -DSEEED_XIAO_M0 -DUSB_VID=0x2886 -DUSB_PID=0x802F -DUSBCON -DUSB_CONFIG_POWER=100 "-DUSB_MANUFACTURER=\"Seeed\"" "-DUSB_PRODUCT=\"Seeed XIAO M0\"" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore/tinyusb/src" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS\\5.7.0/CMSIS/Core/Include/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS\\5.7.0/CMSIS/DSP/Include/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS-Atmel\\1.2.1/CMSIS-Atmel/CMSIS/Device/ATMEL/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\variants\\XIAO_m0" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\libraries\\DCC_Decoder-master" "C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Temp\\arduino-sketch-E8C477A82A9968D483CF46B123C568F8\\sketch\\Dapol_Signal_Xiao.ino.cpp" -o "C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Temp\\arduino-sketch-E8C477A82A9968D483CF46B123C568F8\\preproc\\ctags_target_for_gcc_minus_e.cpp"
"C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\builtin\\tools\\ctags\\5.8-arduino11/ctags" -u --language-force=c++ -f - --c++-kinds=svpf --fields=KSTtzns --line-directives "C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Temp\\arduino-sketch-E8C477A82A9968D483CF46B123C568F8\\preproc\\ctags_target_for_gcc_minus_e.cpp"
Compiling sketch...
"C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\arm-none-eabi-gcc\\7-2017q4/bin/arm-none-eabi-g++" -mcpu=cortex-m0plus -mthumb -c -g -Os -std=gnu++14 -ffunction-sections -fdata-sections -fno-threadsafe-statics -nostdlib --param max-inline-insns-single=500 -fno-rtti -fno-exceptions -MMD "-D__SKETCH_NAME__=\"\"\"Dapol_Signal_Xiao.ino\"\"\"" -DF_CPU=48000000L -DARDUINO=10607 -DARDUINO_SEEED_XIAO_M0 -DARDUINO_ARCH_SAMD -DARDUINO_SAMD_ZERO -D__SAMD21__ -D__SAMD21G18A__ -DARM_MATH_CM0PLUS -DSEEED_XIAO_M0 -DUSB_VID=0x2886 -DUSB_PID=0x802F -DUSBCON -DUSB_CONFIG_POWER=100 "-DUSB_MANUFACTURER=\"Seeed\"" "-DUSB_PRODUCT=\"Seeed XIAO M0\"" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore/tinyusb/src" -DARDUINO_SAMD_ZERO -D__SAMD21__ -D__SAMD21G18A__ -DARM_MATH_CM0PLUS -DSEEED_XIAO_M0 -DUSB_VID=0x2886 -DUSB_PID=0x802F -DUSBCON -DUSB_CONFIG_POWER=100 "-DUSB_MANUFACTURER=\"Seeed\"" "-DUSB_PRODUCT=\"Seeed XIAO M0\"" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore/tinyusb/src" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS\\5.7.0/CMSIS/Core/Include/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS\\5.7.0/CMSIS/DSP/Include/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS-Atmel\\1.2.1/CMSIS-Atmel/CMSIS/Device/ATMEL/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\variants\\XIAO_m0" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\libraries\\DCC_Decoder-master" "C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Temp\\arduino-sketch-E8C477A82A9968D483CF46B123C568F8\\sketch\\Dapol_Signal_Xiao.ino.cpp" -o "C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Temp\\arduino-sketch-E8C477A82A9968D483CF46B123C568F8\\sketch\\Dapol_Signal_Xiao.ino.cpp.o"
C:\Users\Keith.DESKTOP-55532Q9\Documents\Arduino\Dapol_Signal_Xiao\Dapol_Signal_Xiao.ino:12:3: warning: 'typedef' was ignored in this declaration
typedef struct DCCAccessoryData {
^~~~~~~
Compiling libraries...
Compiling library "DCC_Decoder-master"
"C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\arm-none-eabi-gcc\\7-2017q4/bin/arm-none-eabi-g++" -mcpu=cortex-m0plus -mthumb -c -g -Os -std=gnu++14 -ffunction-sections -fdata-sections -fno-threadsafe-statics -nostdlib --param max-inline-insns-single=500 -fno-rtti -fno-exceptions -MMD "-D__SKETCH_NAME__=\"\"\"Dapol_Signal_Xiao.ino\"\"\"" -DF_CPU=48000000L -DARDUINO=10607 -DARDUINO_SEEED_XIAO_M0 -DARDUINO_ARCH_SAMD -DARDUINO_SAMD_ZERO -D__SAMD21__ -D__SAMD21G18A__ -DARM_MATH_CM0PLUS -DSEEED_XIAO_M0 -DUSB_VID=0x2886 -DUSB_PID=0x802F -DUSBCON -DUSB_CONFIG_POWER=100 "-DUSB_MANUFACTURER=\"Seeed\"" "-DUSB_PRODUCT=\"Seeed XIAO M0\"" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore/tinyusb/src" -DARDUINO_SAMD_ZERO -D__SAMD21__ -D__SAMD21G18A__ -DARM_MATH_CM0PLUS -DSEEED_XIAO_M0 -DUSB_VID=0x2886 -DUSB_PID=0x802F -DUSBCON -DUSB_CONFIG_POWER=100 "-DUSB_MANUFACTURER=\"Seeed\"" "-DUSB_PRODUCT=\"Seeed XIAO M0\"" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino/TinyUSB/Adafruit_TinyUSB_ArduinoCore/tinyusb/src" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS\\5.7.0/CMSIS/Core/Include/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS\\5.7.0/CMSIS/DSP/Include/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\tools\\CMSIS-Atmel\\1.2.1/CMSIS-Atmel/CMSIS/Device/ATMEL/" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\cores\\arduino" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\variants\\XIAO_m0" "-IC:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\libraries\\DCC_Decoder-master" "C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Arduino15\\packages\\Seeeduino\\hardware\\samd\\1.8.2\\libraries\\DCC_Decoder-master\\DCC_Decoder.cpp" -o "C:\\Users\\Keith.DESKTOP-55532Q9\\AppData\\Local\\Temp\\arduino-sketch-E8C477A82A9968D483CF46B123C568F8\\libraries\\DCC_Decoder-master\\DCC_Decoder.cpp.o"
C:\Users\Keith.DESKTOP-55532Q9\AppData\Local\Arduino15\packages\Seeeduino\hardware\samd\1.8.2\libraries\DCC_Decoder-master\DCC_Decoder.cpp:49:20: error: stray '\223' in program
Serial.println(�This is the message to look for�);
^
C:\Users\Keith.DESKTOP-55532Q9\AppData\Local\Arduino15\packages\Seeeduino\hardware\samd\1.8.2\libraries\DCC_Decoder-master\DCC_Decoder.cpp:49:52: error: stray '\224' in program
Serial.println(�This is the message to look for�);
^
C:\Users\Keith.DESKTOP-55532Q9\AppData\Local\Arduino15\packages\Seeeduino\hardware\samd\1.8.2\libraries\DCC_Decoder-master\DCC_Decoder.cpp: In static member function 'static void DCC_Decoder::DCC_Interrupt()':
C:\Users\Keith.DESKTOP-55532Q9\AppData\Local\Arduino15\packages\Seeeduino\hardware\samd\1.8.2\libraries\DCC_Decoder-master\DCC_Decoder.cpp:49:21: error: 'This' was not declared in this scope
Serial.println(�This is the message to look for�);
^~~~
Using library DCC_Decoder-master at version 1.6 in folder: C:\Users\Keith.DESKTOP-55532Q9\AppData\Local\Arduino15\packages\Seeeduino\hardware\samd\1.8.2\libraries\DCC_Decoder-master
Compilation error: exit status 1
Looks like a few steps back needed. 
Does the message at the end of setup show up ? An easy way to assure which file is being used is to put an obvious error in place and see that the compiler fails on it.
I have renamed all the other instances of dcc_decoder.h and .cpp so that the only files available to the sketch are the ones being worked on.
I have put
delay(5000); Serial.begin(9600);
at the end of the void setup() section of the sketch
Still nothing printing to monitor.
The delay should go after the begin to assure enough time to actually start then a message printed inside startup() to see if ANY messages get thru. Assure the monitor is set to the same speed as in the begin(9600)
Swapped the Serial.begin and delay around.
All that happens is it prints the computer time in the monitor (was doing it before)
Is this anything to do with setting interrupts?
The goal is to find out if the interrupt routine is ever being visited. Putting a message to be printed inside there is one way to prove that. If you are successfully printing messages yet the message inside the interrupt routine is not being printed then the interrupt routine is not being visited. Your interrupt is used to time the pulses of the data stream in order to decode the message. No interrupt - no message to drive the rest of the process.
Next is to find out why it isn’t being visited, The problem is either no proper data stream (IE poor logic levels [Xiao 3.3V Nano 5V] or data stream on the wrong pin) or something improper in the interrupt setup (your code must identify the interrupt service routine and say which pin is to be used) . Earlier I went thru the library to see what those calls where but it’s been so long that I no longer remember so it’s up to you to identify those.