HD6417727BP160CV Datasheet, PDF (815/1098 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family/ SH7700 Series

Section 24 USB HOST Module
24.3 Data Storage Format which Required by USB Host Controller
24.3.1 Storage Format of the Transferred Data
USB Host Controller expects that data are compiled from lower address to upper address
regardless endian setting of the CPU. Below figure shows data read operation which is done by
USB Host Controller.
Program
DATA.L H'11223344
DATA.L H'55667788
DATA.L H'00000099
Memory (Area 3)
+3 +2 +1 +0
11 22 33 44
+7 +6 +5 +4
55 66 77 88
+11 +10 +9 8
00 00 00 99
USB host
LW read H'11223344
LW read H'55667788
LW read H'00000099
The correspondence between data in memory and data read by USB Host Controller must be
equal. When USB Host Controller reads data from external memory, USB Host Controller reads
data by long word read operation every time regardless that the read data are written in byte ,word
or long word. USB Host Controller uses data in byte from lower address in long word which it
reads regardless the endian mode. Even endian mode is set as big or little, set the data from down
addresses.
Below program flow is the example of failure.
1^st In program, set transfer address A to register R0 at big endian
2^nd In program, “MOV.B #H'12,@R0”
3^rd In program , set transfer start address A to USB Host Controller , and set 1byte as transfer
size.
Memory
+3 +2 +1 +0
12 00 00 00
Data expected to be transferred
LW read H ' 1 2 0 0 0 0 0 0
Actually transferred data
This example show that above operation transfers expected data #H'12.
Rev.6.00 Mar. 27, 2009 Page 757 of 1036
REJ09B0254-0600