Section 7 Bus State Controller (BSC)
Rev. 2.00 Mar 09, 2006 page 282 of 906
REJ09B0292-0200
D7
7
0
D0
7
0
7
0
7
0
7
0
15
8
7
0
15
8
7
0
15
8
23
16
31
24
A24–A0
000000
000001
000002
000003
000000
000001
000002
000003
000000
000001
000002
000003
Data input/output pin
Byte read/write of address 0
Byte read/write of address 1
Byte read/write of address 2
Byte read/write of address 3
Word read/write of address 0
Word read/write of address 2
Longword read/write of address 0
8-bit external device (little-endian)
Figure 7.10 8-Bit External Devices and Their Access Units
7.4
Accessing Ordinary Space
7.4.1
Basic Timing
A strobe signal is output by ordinary space accesses of CS0–CS4 spaces to provide primarily for
SRAM direct connections. Figure 7.11 shows the basic timing of ordinary space accesses.
Ordinary accesses without waits end in 2 cycles. The
BS
signal is asserted for 1 cycle to indicate
the start of the bus cycle. The
CSn
signal is negated by the fall of clock T2 to ensure the negate
period. The negate period is thus half a cycle when accessed at the minimum pitch.
The access size is not specified during a read. The correct access start address will be output to the
LSB of the address, but since no access size is specified, the read will always be 32 bits for 32-bit
devices and 16 bits for 16-bit devices. For writes, only the
WE
signal of the byte that will be
written is asserted. For 32-bit devices,
WE3
specifies writing to a 4n address and
WE0
specifies
writing to a 4n+3 address. For 16-bit devices,
WE1
specifies writing to a 2n address and
WE0
specifies writing to a 2n+1 address. For 8-bit devices, only
WE0
is used.
When data buses are provided with buffers, the
RD
signal must be used for data output in the read
direction. When RD/
WR
signals do not perform accesses, the chip stays in read status, so there is a
danger of conflicts occurring with output when this is used to control the external data buffer.
Содержание SH7616
Страница 10: ...Rev 2 00 Mar 09 2006 page x of xxvi ...
Страница 132: ...Section 2 CPU Rev 2 00 Mar 09 2006 page 106 of 906 REJ09B0292 0200 ...
Страница 568: ...Section 12 16 Bit Free Running Timer FRT Rev 2 00 Mar 09 2006 page 542 of 906 REJ09B0292 0200 ...
Страница 582: ...Section 13 Watchdog Timer WDT Rev 2 00 Mar 09 2006 page 556 of 906 REJ09B0292 0200 ...
Страница 662: ...Section 14 Serial Communication Interface with FIFO SCIF Rev 2 00 Mar 09 2006 page 636 of 906 REJ09B0292 0200 ...
Страница 706: ...Section 16 Serial I O SIO Rev 2 00 Mar 09 2006 page 680 of 906 REJ09B0292 0200 ...
Страница 820: ...Section 19 Pin Function Controller PFC Rev 2 00 Mar 09 2006 page 794 of 906 REJ09B0292 0200 ...
Страница 932: ...Appendix D Package Dimensions Rev 2 00 Mar 09 2006 page 906 of 906 REJ09B0292 0200 ...
Страница 935: ...SH7616 Hardware Manual ...