Host Bus Mode
1201
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
External Peripheral Interface (EPI)
In quad chip select mode (CSCFGEXT is 0x1 and CSCFG is 0x1 or 0x2 in the EPIHBnCFG2 register),
both the peripheral and the memory space must be enabled.
In the EPIADDRMAP register, the EPADR field is 0x3, the ERADR field is 0x3, and the ECADR field is
0x0. With this configuration, CS0 asserts for the address range beginning at 0x6000.0000, CS1 asserts for
0x8000.0000, CS2 for 0xA000.0000, and CS3 for 0xC000.0000.
gives a detailed explanation of chip select address range mappings based on combinations of
enabled peripheral and memory space.
(1)
When CS0 and CS1 share address space, CS0 asserts when the MSB of the address is '0' and CS1, when the MSB of the
address is '1'.
Table 17-3. Dual- and Quad- Chip Select Address Mappings
Chip Select
Mode
ERADR
EPADR
ECADR
CS0
(1)
CS1
CS2
CS3
Dual-chip
select
0x0
0x1 or 0x2
0x0
EPADR
defined
address range
(0xA000.0000
or
0xC000.0000)
EPADR
defined
address range
(0xA000.0000
or
0xC000.0000)
N/A
N/A
Dual-chip
select
0x1 or 0x2
0x0
0x0
ERADR
defined
address range
(0x6000.0000
or
0x8000.000)
ERADR
defined
address range
(0x6000.0000
or
0x8000.000)
N/A
N/A
Dual-chip
select
0x1 or 0x2
0x1 or 0x2
0x0
EPADR
defined
address range
(0xA000.0000
or
0xC000.0000)
ERADR
defined
address range
(0x6000.0000
or
0x8000.0000)
N/A
N/A
Dual-chip
select
0x0
0x1 or 0x2
0x1
ECADR
defined
address range
(0x1000.0000)
EPADR
defined
address range
(0xA000.0000
or
0xC000.0000)
N/A
N/A
Dual-chip
select
0x1 or 0x2
0x0
0x1
ECADR
defined
address range
(0x1000.0000)
ERADR
defined
address range
(0x6000.0000
or
0x8000.0000)
N/A
N/A
Quad-chip
select
0x3
0x3
0x0
0x6000.0000
0x8000.0000
0xA000.0000
0xC000.0000
Tri-chip select
0x3
0x3
0x0
0x6000.0000
N/A
0xA000.0000
0xC000.0000
The MODE field of the EPIHBnCFGn registers configure the interface for the chip selects, which support
ADMUX or ADNOMUX. See
for details on which configuration register controls each chip
select. If the CSBAUD bit is clear, all chip selects are configured by the MODE bit field of the EPIHBnCFG
register.
If the CSBAUD bit in the EPIHBnCFG2 register is set in dual-chip select mode, the two chip selects can
use different clock frequencies, wait states and strobe polarity. If the CSBAUD bit is clear, both chip
selects use the clock frequency, wait states, and strobe polarity defined for CS0. Additionally, if the
CSBAUD bit is set, the two chip selects can use different interface modes. If any interface modes are
programmed to ADMUX, then dual chip select mode must include the ALE capability. In quad chip select
mode, if the CSBAUD bit in the EPIHBnCFG2 register is set, the four chip selects can use different clock
frequencies, wait states and strobe polarity. If the CSBAUD bit is clear, all chip selects use the clock
frequency, wait states, and strobe polarity defined for CS0. If the CSBAUD bit is set, the four chip selects
can use different interface modes