5. Connection Example with FreeScale iMX21
16
EPSON
S1R72V17 CPU Connection Guide
(Rev. 1.0)
5.2
iMX21 Bus Cycle Setting Example
•
iMX21 clock settings
The iMX21 clock settings are set as shown below in this connection example.
System clock: 264 MHz
CPU-IF bus clock (HCLK): 88 MHz (system clock 3 divisions)
•
Bus cycle settings
CS1U register (0xDF001008 address)
Setting: 0x0402_0700
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
SP
WP
PME SYNC
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
EW
CS1L register (0xDF00100C address)
Setting: 0x4200_0D01
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
EBC
PSR CRE WRAPCSEN
Setting descriptions
Register
Setting
Description
RWA
4'b0100
RW output assert timing (2HCLK)
SYNC
1'b0
Synchronous transfer mode (disabled)
RWN
4'b0010
RW output negate timing (1HCLK)
WSC
6'b000111
Access cycle (8HCLK)
WWS
3'b000
Wait cycle for write (0HCLK)
OEA
4'b0100
OE output assert timing (2HCLK)
OEN
4'b0010
OE output negate timing (1HCLK)
WEA
4'b0000
EBx output assert timing (0HCLK)
WEN
4'b0000
EBx output negate timing (0HCLK)
CSA
4'b0000
CS1 output assert timing (0HCLK)
EBC
1'b1
EB3, 2 output mode for read (disabled)
DSZ
3'b101
Data bus size (using 16 bits [15:0])
CSN
4'b0000
CS1 output assert timing (0HCLK)
CSEN
1'b1
CS1 enable (enabled)
DSZ
CSN
OEA
OEN
WEA
CSA
WEN
CNC
WSC
WWS
EDC
DCT
RWA
PSZ
RWN
Fig. 5-2 Bus cycle setting registers