From the header of the firmware updating tool it looks like a R5F61653RN50FPV CPU from Renesas. Unfortunatly as of the time writing the datasheet is not found on the Renesas webpage alternative location
; ******************************************
; ** [FILENAME] AH067_V0204.SFL **
; ** [DATE] 2020/03/04 **
; ** [CPU] R5F61653RN50FPV **
; ** [PRODUCT NAME] FT-991A **
; ** [FIRM Version] V0204 **
; ** [R code] YR **
; ** [CHECK SUM] 03702228(00000-5FFFF) **
; ******************************************
The MCU datasheet tells us the the MCU has 4 operating modes. (starting from page 27)
- normal mode (max 64kb overall)
- middle mode (64kb program area, 16MB data area)
- advanced mode (16MB program aread, 4GB data)
- maximum mode (program area, data area 4GB)
Q: which is is used in the FT991a? Guess: Advanced mode, as
- the firmware header looks like 24bit addressing and
- the
SPRabc;CAT command seems to expect 24bit in abc.
Q: How about segmentation? Guess: flat
Starting on page 33 the startup of the MCU is described.
... to be done ...
Guess: Flash memory located at 0x000000, at least 6MB large. And we need an entrypoint vector in 0x000000, according to the boot up.
Q: Where is some RAM located?