While searching for ways to transmit Pager messages I found this nice post:
There are many ways to transmit to pager using the POCSAG protocol, but I decided to buy a MMDVM Raspberry Pi Hat board: https://aliexpress.com/item/32915442246.html
I bought the model “MMDVM OLED CASE” without the “Raspi 0 W” because I already have one! Then I spent around U$ 30,00 with free shipping, very good!
When it arrived I mounted it over my Raspi board running Raspbian 11.
Basically I cloned and compiled the MMDVMHost and its dependencies like WiringPi and “ArduiPi OLED”.
After compiling and installing I moved the file MMDVM.ini to /etc/ and edited it to enable POCSAG protocol and “Remote Control”.
Unfortunately while running the “RemoteCommand 7642 page 1000001 Ola Mundo” it was returning this error message:
“Received a NAK to the SET_FREQ command from the modem”
It was fixed changing RXFrequency, TXFrequency and POCSAG Frequency to 433450000.
Unfortunately many forums has this issue but nobody explain the root cause, some report the issue was caused by incompatible MMDVM_HS firmware version, duplex config enable for this board that doesn’t support duplex, etc. The only place where I found the right root cause was here:
Because of it I spent time testing many configurations, updating firmware, etc. At least I’m now using a more updated firmware, from MMDVM_HS_Hat-v1.4.17 to MMDVM_HS_Hat-v1.5.2