
10 AHB-DECODER
96
EPSON
S1C38000 TECHNICAL MANUAL
10 AHB-Decoder
10.1 Overview
The AHB-Decoder (AHDEC) decodes the upper four address bits of the AHB bus and issues a
SLVSEL signal to the AHB slave components to identify that it is selected for access. There are 32
pages of 128M byte memory space assigned to slave components whose space arrangement is
managed by the AHDEC. The CPU can re-map address space by reprogramming the AHDEC
registers. Re-mapping is initiated by writing to the Clear Reset Map Register of the State Controller.
See Section 7.2, “Memory Map” on page 82 for the default address mapping.
10.2 Register Descriptions
The AHDEC has four 32-bit address mapping registers organized into 32 4-bit groups. Each group
represents a chunk of 128M byte memory space. The value programmed into each 4-bit group
represents the memory space assignment for a particular AHB slave. There are four AHB slaves in
the S1C38000.
The default base address for the AHDEC registers is F8000000h. All non-reserved register bits
default to 0 unless specified otherwise. The ARM720T is selected only during TIC test mode.
bits 31–28 Bank 7
(address range 3FFFFFFFh–38000000h)
bits 27–24 Bank 6
(address range 37FFFFFFh–30000000h)
bits 23–20 Bank 5
(address range 2FFFFFFFh–28000000h)
bits 19–16 Bank 4
(address range 27FFFFFFh–20000000h)
bits 15–12 Bank 3
(address range 1FFFFFFFh–18000000h)
bits 11–8
Bank 2
(address range 17FFFFFFh–10000000h)
bits 7–4
Bank 1
(address range 0FFFFFFFh–08000000h)
bits 3–0
Bank 0
(address range 07FFFFFFh–00000000h)
Table 10-1 Address Map Register Value Definition
Symbol
Register
Value
Description
SLVSEL0
0000
MIC static memory space
SLVSEL1
0001
MIC SDRAM memory space
SLVSEL2
0010
APB peripherals memory space accessed via APB Bridge
SLVSEL3
0011
S1D13706 LCDC memory space
A720TSLV
0111
ARM720T slave mode space (only effective in chip test mode)
AHDEC
1111
Unspecified
others
Same as AHDEC
Address Map Register 0
AHB[00h]
Default = FFFF FFF0h
Read/Write
Bank 7
Bank 6
Bank 5
Bank 4
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Bank 3
Bank 2
Bank 1
Bank 0
15
14
13
12
11
10
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