UPSD3212C, UPSD3212CV
Memory Select Configuration in Program and
Data Spaces. The MCU Core has separate ad-
dress spaces for Program memory and Data
memory. Any of the memories within the PSD
MODULE can reside in either space or both spac-
es. This is controlled through manipulation of the
VM Register that resides in the CSIOP space.
The VM Register is set using PSDsoft Express to
have an initial value. It can subsequently be
changed by the MCU so that memory mapping
can be changed on-the-fly.
For example, you may wish to have SRAM and pri-
mary Flash memory in the Data space at Boot-up,
and secondary Flash memory in the Program
space at Boot-up, and later swap the primary and
secondary Flash memories. This is easily done
with the VM Register by using PSDsoft Express
Configuration to configure it for Boot-up and hav-
ing the MCU change it when desired. Table 66 de-
scribes the VM Register.
Table 66. VM Register
Bit 4
Bit 2
Primary
FL_Code
Bit 7
Bit 3
Secondary Data
Bit 1
Bit 0
Bit 6
Bit 5
Primary
PIO_EN
Secondary Code SRAM_Code
FL_Data
0 = RD
can’t
0 = PSEN
can’t
access Secondary access
0 = PSEN
0 = PSEN can’t
can’t
0 = RD can’t
0 = disable
PIO Mode
not used not used access
access Secondary
access
Flash
memory
Flash memory
Flash
memory
Flash memory
SRAM
1 = RD
1 = PSEN
access
Flash
1 = RD access
Secondary Flash
memory
1 = PSEN access 1 = PSEN
1= enable
PIO Mode
access
not used not used
Flash
Secondary Flash
memory
access
SRAM
memory
memory
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STMICROELECTRONICS [ ST ]
