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Device Initialization by ROM Code
Table 26-30. XIP Timing Parameters (continued)
Parameter
Value [Clock Cycles] Register Initialization (where i = 0...7)
Reset Value
OE high time
16
The GPMC_CONFIG4_i[12:8] OEOFFTIME bit field is set to
0x10
0x10.
WE low time
3
The GPMC_CONFIG4_i[19:16] WEONTIME bit field is set to
0x03
0x3.
WE high time
15
The GPMC_CONFIG4_i[28:24] WEOFFTIME bit field is set to
0x10
0xF.
Data latch time
15
The GPMC_CONFIG5_i[20:16] RDACCESSTIME bit field is
0x0F
set to 0xF.
26.4.7.4 NAND
NAND flash memory is not an XIP booting device; it requires shadowing before the code can be executed.
ROM code support for the NAND flash booting devices has the following characteristics:
•
The GPMC is the communication interface.
•
Device from 64 Mb (8MB)
•
x8 and x16 bus width
•
Small page size (512 bytes + 16 bytes) and large page size (2048 bytes + 64 bytes)
•
Chip enable (CE) don't care booting devices only
•
Single level cell (SLC) and multilevel cell (MLC) devices
•
Device identification is based on standard identification data or ID2 protocol.
•
One-bit error checking and correction (ECC) is used to protect a 512-byte sector.
•
GPMC timings are adjusted for NAND access.
•
The GPMC clock is 48 MHz.
•
The booting device is connected to CS0.
•
The wait pin signal gpmc_wait0 is connected to the NAND BUSY output.
•
Four physical blocks are searched for image. Block size depends on the booting device.
For NAND memory booting, no user intervention is needed; the information in the following subsections is
included for debugging. Only the CH, which is not mandatory, lets the user change clock settings and
GPMC parameters. Failure in CH copying causes a return to the main booting procedure, which selects
the next booting device for booting.
26.4.7.4.1 Initialization and NAND Detection
The initialization routine for NAND consists of three parts: GPMC initialization, booting device detection
with parameter determination, and bad block detection/verification.
•
GPMC initialization
The GPMC interface is configured so that it can access NANDs. Because NANDs do not need the
address bus, it is released. The data bus width is initially set to 8 bits. If necessary, it is changed to 16
bits after the booting device parameters are determined.
shows the GPMC configuration
used during NAND boot.
is included for debug information.
Table 26-31. NAND Timing Parameters
Parameter
Value [Clock Cycles]
Register Initialization (where i = 0...7)
Reset Value
Write cycle time
20
The GPMC_CONFIG5_i[12:8] WRCYCLETIME
0x11
bit field is set to 0x14.
Read cycle time
20
The GPMC_CONFIG5_i[4:0] RDCYCLETIME bit
0x11
field is set to 0x14.
CS low time
0
The GPMC_CONFIG2_i[3:0] CSONTIME bit field
0x1
is set to 0x0.
OE low time
5
The GPMC_CONFIG4_i[3:0] OEONTIME bit field
0x3
is set to 0x5.
3545
SWPU177N – December 2009 – Revised November 2010
Initialization
Copyright © 2009–2010, Texas Instruments Incorporated
Содержание OMAP36 Series
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