SH7125_08 Datasheet, PDF (643/774 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family

Section 17 Flash Memory
17.7 Usage Notes
17.7.1 Interrupts during Programming/Erasing
(1) Download of On-Chip Program
(1.1) VBR setting change
Before downloading the on-chip program, VBR must be set to H'84000000. If VBR is set to a
value other than H'84000000, the interrupt vector table is placed in the user MAT on setting
H'84000000 to VBR.
When VBR setting change conflicts with interrupt occurrence, whether the vector table before
or after VBR is changed is referenced may cause an error.
Therefore, for cases where VBR setting change may conflict with interrupt occurrence, prepare
a vector table to be referenced when VBR is H'00000000 (initial value) at the start of the user
MAT.
(1.2) SCO download request and interrupt request
Download of the on-chip programming/erasing program that is initiated by setting the SCO bit
in FCCS to 1 generates a particular interrupt processing accompanied by MAT switchover.
Operation when the SCO download request and interrupt request conflicts is described below.
1. Contention between SCO download request and interrupt request
Figure 17.14 shows the timing of contention between execution of the instruction that sets
the SCO bit in FCCS to 1 and interrupt acceptance.
CPU cycle
CPU operation for instruction
that sets SCO bit to 1
Interrupt acceptance
n
Fetch
n+1
Decoding
(a)
n+2
Execution
(b)
n+3
Execution
n+4
Execution
(a) When the interrupt is accepted at the (n + 1) cycle or before
After the interrupt processing completes, the SCO bit is set to 1 and download is executed.
(b) When the interrupt is accepted at the (n + 2) cycle or later
The interrupt will conflicts with the SCO download request. Ensure that no interrupt is generated.
Figure 17.14 Timing of Contention between SCO Download Request and Interrupt Request
2. Generation of interrupt requests during downloading
Ensure that interrupts are not generated during downloading that is initiated by the SCO
bit.
Rev. 4.00 Jul. 25, 2008 Page 623 of 750
REJ09B0243-0400