<![CDATA[CoreS3 and unit CatM GNSS cannot cooperate]]>hi Community,

i'm pretty new to M5stack solutions and i'm enjoying variety of products which are great.

However, I'm struggling to make CatM GNSS unit to cooperate with CoreS3

it's exactly this unit https://docs.m5stack.com/en/unit/catm_gnss which is using port C of CoreS3, so I'm trying to use ports 17 and 18 as Rx and Tx in my code. When I run my code, I'm getting no connectivity or data flowing from CatM and GNSS unit. To omit issues with simcard, i firstly try to make GNSS working and despite red and blue leds are flashing, no data is being receiced.

Is there anyone in our Community that would be so kind and share a working piece of code between CoreS3 and CatM GNSS unit?

Maybe I'm not using correct libraries? I'm using those:

https://github.com/m5stack/M5CoreS3/blob/main/src/M5CoreS3.h
M5GFX.h
https://github.com/m5stack/M5Unit-CatM/blob/60528f5b02106dd38aac3ddd2be61f8ac081cd31/src/M5Unit-CatM.h

Please help in figuring out what am I missing?

Regards and have a good time with M5Stack products!

]]>https://community.m5stack.com/topic/6282/cores3-and-unit-catm-gnss-cannot-cooperateRSS for NodeMon, 09 Mar 2026 00:09:28 GMTSun, 31 Mar 2024 21:35:46 GMT60<![CDATA[Reply to CoreS3 and unit CatM GNSS cannot cooperate on Tue, 02 Apr 2024 12:48:39 GMT]]>Felix @felmue OMG, this was so easy...many thanks, that was the reason why the unit wasn't reacting for any commands. Have a nice day

]]>https://community.m5stack.com/post/24649https://community.m5stack.com/post/24649Tue, 02 Apr 2024 12:48:39 GMT<![CDATA[Reply to CoreS3 and unit CatM GNSS cannot cooperate on Sun, 31 Mar 2024 22:48:06 GMT]]>Hello @jaro99

you might have RX and TX reversed. See pin map here. RX is 18 and TX is 17.

CoreS3 TX ---> GPIO17 ---> RX Modem
CoreS3 RX <--- GPIO18 <--- TX Modem

Thanks
Felix

]]>https://community.m5stack.com/post/24624https://community.m5stack.com/post/24624Sun, 31 Mar 2024 22:48:06 GMT