Hi hmani,
unfortunately this behavior isn't intermittent: When I set the MASK bit for WFSM to 0 manually or by performing a software reset, the status bit for WFSM won't change from 0 to 1 and the value I read from WFORM stays at 0x00. When the MASK bit for WFSM is being set to 1, the status bit for WFSM changes to 1 and I can read reasonable (!!!) values from the WFORM register.
Reading address 0x7D immediately after a software reset (no other actions performed) returns a value of 0xF7 just like it does without the software reset. I only have one ADE7758 in use so far, as my project is academic and has no commercial background at this stage.
I've created some scope plots of the communication port for the current problem. If you need to see other plots, just let me know and I'll do what I can.
#1: writing 0x10 to WAVMODE register (0x15) followed by reading WAVMODE register (0x15)
#2: reading RSTATUS (0x1A) followed by reading STATUS register (0x19) without MASK bit for WFSM set
#3: reading WFORM (0x12) without MASK bit for WFSM set
#4: writing 0x10000 to MASK register (0x18) followed by reading MASK register (0x18)
#5: reading RSTATUS (0x1A) followed by reading STATUS (0x19) with MASK bit for WFSM set
#6: reading WFORM (0x12) with MASK bit for WFSM set
I also tried to write to address 0x7D with a value of 0xF7 as you suggested. I can write to this register and change the value to what I want it to be but as it is 0xF7 by default this action doesn't change anything.
I really appreciate your help.
Best regards
Mathias