HD6417727BP160CV Datasheet, PDF (373/1098 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family/ SH7700 Series

Section 12 Bus State Controller (BSC)
12.2.12 Cautions on Accessing Refresh Control Related Registers
RFCR, RTCSR, RTCNT, and RTCOR require that a specific code be appended to the data when it
is written to prevent data from being mistakenly overwritten by program overruns or other write
operations (figure 12.4). Perform reads and writes using the following methods:
1. Writing to RFCR, RTCSR, RTCNT, and RTCOR
When writing to RFCR, RTCSR, RTCNT, and RTCOR, use only word transfer instructions.
You cannot write with byte transfer instructions.
When writing to RTCNT, RTCSR, or RTCOR, place B'10100101 in the upper byte and the
write data in the lower byte. When writing to RFCR, place B'101001 in the top 6 bits and the
write data in the remaining bits, as shown in figure 12.4.
2. Reading from RFCR, RTCSR, RTCNT, and RTCOR
When reading from RFCR, RTCSR, RTCNT, and RTCOR, carry out reads with 16-bit width.
0 is read out from undefined bit sections.
15
87
0
RTCSR, RTCNT, _{1 0 1 0 0 1 0 1}
RTCOR
15
10 9
Write data
0
RFCR 1 0 1 0 0 1
Write data
Figure 12.4 Writing to RFCR, RTCSR, RTCNT, and RTCOR
Rev.6.00 Mar. 27, 2009 Page 315 of 1036
REJ09B0254-0600