I use the MSP430FR5994 with a LTE modem on the same power supply (3,4V). When the modem is turned OFF, everything is ok, but when it is turned on, the RAM data in the MSP439FR5994 begin to change spontaneously (not always, but from time to time). There is no reset, that takes place in the MSP430, at no time. The power line seems to be stable on the oscilloscope.
Other configuration: Now I placed the MSP430FR5994 on a separate supply power, and the only connection between the MSP430 and the modem is an interrupt line from the modem to the MSP430 (and GND). The problem of the randomly RAM changes remain still there. So the Vcc power line of the MSP430 could be partially excluded for this problem.
So I suppose that it might be a spike on the power line (or the interrupt line), or something else caused by the modem, that changes the RAM content in the MSP430. Has someone encountered a similar problem? What might be the origin? what could be the solution of this problem?
Thank you for your help.