SMC Networks ARM PL241 - Manual (Page 70)

Programmer’s Model
3-10 Copyright © 2006 ARM Limited. All rights reserved. ARM DDI 0389B
3.3.5 SMC Direct Command Register at 0x1010
The write-only smc_direct_cmd Register passes commands to the external memory, and
controls the updating of the chip configuration registers with values held in the
set_opmode and set_cycles registers.
This register cannot be written to in either the Reset or Low-power state. Figure 3-10
shows the register bit assignments.
Figure 3-10 smc_direct_cmd Register bit assignments
Table 3-6 lists the register bit assignments.
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Table 3-6 smc_direct_cmd Register bit assignments
Bits Name Function
[31:26] - Reserved, undefined. Write as zero.
[25:23] chip_select Selects chip configuration register bank to update and enables chip mode register access depending
on cmd_type. The encoding is:
b000-b011 = chip selects 1-4 on interface 0
b100-b111 = reserved.
[22:21] cmd_type Determines the current command. The encoding is:
b00 = UpdateRegs and AHB command
b01 = ModeReg access
b10 = UpdateRegs
b11 = ModeReg and UpdateRegs.
[20] set_cre Maps to configuration register enable, smc_cre, output, when a ModeReg command is issued. The
encoding is:
b0 = smc_cre is LOW
b1 = smc_cre is HIGH when ModeReg write occurs.
[19:0] addr Bits mapped to external memory address bits [19:0] when command is ModeReg access.
Addr[19:16] are undefined.
Addr[15:0] matches wdata[15:0] when the commands are UpdateRegs and AHB command access.