# Error during compilation

**URL:** <https://www.thethingsnetwork.org/forum/t/error-during-compilation/40781>\
**Category:** \[obsolete\] SCPF\
**Created:** [October 22, 2020, 2:36pm UTC](https://www.thethingsnetwork.org/forum/t/error-during-compilation/40781 "2020-10-22T14:36:46Z")\
**Posts on this page:** 9\
**Page:** 1

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**Author:** ![noweare](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/noweare/32/25844_2.png) [@noweare](https://www.thethingsnetwork.org/forum/u/noweare)\
**Post date:** [October 22, 2020, 2:36pm UTC](https://www.thethingsnetwork.org/forum/t/error-during-compilation/40781/1 "2020-10-22T14:36:46Z")

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Hello,  
This is my first attempt at getting a LoRaWan gateway and node to work

The gateway is a single channel gateway based on the code from  
github/things4u/ESP-1ch-Gateway written by Maarten Westenberg.  
I am using an esp32 and a rfm95w radio.

I am using the arduino ide for building the project.

When buiding the project I get and error shown below:

Compiling sketch…  
.  
.  
/home/jrm/Documents/test/ESP-sc-gway/\_txRx.ino: In function ‘int buildPacket(uint8\_t\*, LoraUp\*, bool)’:  
\_txRx:266:42: error: ‘checkMic’ was not declared in this scope  
checkMic(message, messageLength, NwkSKey);  
^  
I tried searching for the checkMic routine but couldn’t find it.  
Also, there are no #include files in the \_txRx.ino file.

Anyone have an idea of why this could be happening?  
Its kind of puzzling because the #if statement looks like this:

#if \_CHECK\_MIC==1  
unsigned char NwkSKey[16] = \_NWKSKEY;  
checkMic(message, messageLength, NwkSKey);  
#endif //\_CHECK\_MIC

and I don’t even know how \_CHECK\_MIC is known in the file  
since there are no #include files.

Thanks for your help

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**Author:** ![kersing](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/kersing/32/44777_2.png) [@kersing](https://www.thethingsnetwork.org/forum/u/kersing)\
**Post date:** [October 22, 2020, 4:15pm UTC](https://www.thethingsnetwork.org/forum/t/error-during-compilation/40781/2 "2020-10-22T16:15:02Z")

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Single channel packet forwarders harm the LoRaWAN network and are incompatible. They’re not supported on TTN and should not be used,  
This forum does not provide support for them.

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**Author:** ![noweare](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/noweare/32/25844_2.png) [@noweare](https://www.thethingsnetwork.org/forum/u/noweare)\
**Post date:** [October 22, 2020, 5:00pm UTC](https://www.thethingsnetwork.org/forum/t/error-during-compilation/40781/3 "2020-10-22T17:00:28Z")

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Maybe it’s not a single channel packet forwarder then. It’s a single channel gateway that doesn’t harm anything that I know. The library used is the arduino-lmic by matt. Maybe I just posted in the wrong section.

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**Author:** ![kersing](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/kersing/32/44777_2.png) [@kersing](https://www.thethingsnetwork.org/forum/u/kersing)\
**Post date:** [October 22, 2020, 5:27pm UTC](https://www.thethingsnetwork.org/forum/t/error-during-compilation/40781/4 "2020-10-22T17:27:28Z")

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There is noch thing as a single channel gateway. The LoRaWAN specification requires a gateway to have multiple channels. The hardware usually used has 8.  
And a module with just one channel will hurt the network.

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**Author:** ![LoRaTracker](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/loratracker/32/48502_2.png) [@LoRaTracker](https://www.thethingsnetwork.org/forum/u/LoRaTracker)\
**Post date:** [October 22, 2020, 5:29pm UTC](https://www.thethingsnetwork.org/forum/t/error-during-compilation/40781/5 "2020-10-22T17:29:41Z")

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> [@noweare](#):
>
> It’s a single channel gateway that doesn’t harm anything that I know.

Unfortunately its not a case of what you dont know does not cause any harm.

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**Author:** ![noweare](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/noweare/32/25844_2.png) [@noweare](https://www.thethingsnetwork.org/forum/u/noweare)\
**Post date:** [October 22, 2020, 5:35pm UTC](https://www.thethingsnetwork.org/forum/t/error-during-compilation/40781/6 "2020-10-22T17:35:40Z")

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So why have a section for single channel gateways in the forum ?

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**Author:** ![kersing](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/kersing/32/44777_2.png) [@kersing](https://www.thethingsnetwork.org/forum/u/kersing)\
**Post date:** [October 22, 2020, 6:10pm UTC](https://www.thethingsnetwork.org/forum/t/error-during-compilation/40781/7 "2020-10-22T18:10:04Z")

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Because 4 years ago it seemed a good idea, now we know about the issued caused by them.

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**Author:** ![noweare](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/noweare/32/25844_2.png) [@noweare](https://www.thethingsnetwork.org/forum/u/noweare)\
**Post date:** [October 22, 2020, 6:11pm UTC](https://www.thethingsnetwork.org/forum/t/error-during-compilation/40781/8 "2020-10-22T18:11:20Z")

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Ok, thanks

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<div class="post-metadata">

**Author:** ![kersing](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/kersing/32/44777_2.png) [@kersing](https://www.thethingsnetwork.org/forum/u/kersing)\
**Post date:** [October 22, 2020, 6:13pm UTC](https://www.thethingsnetwork.org/forum/t/error-during-compilation/40781/9 "2020-10-22T18:13:53Z")

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