[werk_ag]

Tried the EEPROM.write procedure. What happens is: after the second reprogram, after around two minutes, the RX hangs for a few seconds and then reboots alone..

In those few seconds it is just filling the two eprooms with zeros.
This step has performed normally.

When it comes back, after a while, it hangs one more time (without self rebooting, I have to unplug the power) and then apparently starts to work normally.

Hanging at this step, is not normal! At this step is when it writes important data to both eeproms.
If you repeat the procedure, it always hangs here?

Just to check add this three lines before line 334

Code:

Serial.println(Ext_eepromReadInt(0x29));
Serial.println(Ext_eepromReadInt(0x2B));
Serial.println(Ext_eepromReadInt(0x2D));

and see what you get with serial monitor.
It should return:
62
81
xx - Your defined Archive Period (1, I think)