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EPI Registers
1140
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
External Peripheral Interface (EPI)
Table 16-21. EPIHB8CFG2 Register Field Descriptions (continued)
Bit
Field
Type
Reset
Description
26
CSBAUD
R/W
0x0
Chip Select Baud Rate and Multiple Sub-Mode Configuration enable
This bit is only valid when the CS CSCFG field is
programmed to 0x2 or 0x3, 0x5 or 0x6.
This bit configures the baud rate settings for CS0n, CS1n, CS2n,
and CS3n.
This bit must also be set to allow different sub-mode configurations
on chip-selects.
If this bit is clear, all chip-select sub-modes are based on the MODE
encoding defined in the EPI8HBCFG register.
If the CSBAUD bit is set in the EPIHBnCFG2 register and dual- or
quad-chip selects are enabled, then the individual chip selects can
use different clock frequencies, wait states and strobe polarity.
0x0 = Same Baud Rate and Same Sub-ModeAll CSn use the baud
rate for the external bus that is defined by the COUNT0 field in the
EPIBAUD register and the sub-mode programmed in the MODE field
of the EPIHB8CFG register.
0x1 = Different Baud RatesCS0n uses the baud rate for the external
bus that is defined by the COUNT0 field in the EPIBAUD register.
CS1n uses the baud rate defined by the COUNT1 field in the
EPIBAUD register.CS2n uses the baud rate for the external bus that
is defined by the COUNT0 field in the EPIBAUD2 register. CS3n
uses the baud rate defined by the COUNT1 field in the EPIBAUD2
register.In addition, the sub-modes for each chip select are
individually programmed in their respective EPIHB8CFGn registers.
25-24
CSCFG
R/W
0x0
Chip Select Configuration.
This field controls the chip select options, including an ALE format, a
single chip select, two chip selects, and an ALE combined with two
chip selects.
These bits are also used in combination with the CSCFGEXT bit for
further configurations, including quad- chip select.
0x0 = ALE Configuration. EPI0S30 is used as an address latch
(ALE). The ALE signal is generally used when the address and data
are muxed (HB8MODE field in the EPIHB8CFG register is 0x0). The
ALE signal is used by an external latch to hold the address through
the bus cycle.
0x1 = CSn Configuration. EPI0S30 is used as a Chip Select (CSn).
When using this mode, the address and data are generally not
muxed (HB8MODE field in the EPIHB8CFG register is 0x1).
However, if address and data muxing is needed, the WR signal
(EPI0S29) and the RD signal (EPI0S28) can be used to latch the
address when CSn is low.
0x2 = Dual CSn Configuration. EPI0S30 is used as CS0n and
EPI0S27 is used as CS1n. Whether CS0n or CS1n is asserted is
determined by two methods. If only external RAM or external PER is
enabled in the address map, the most significant address bit for a
respective external address map controls CS0n or CS1n. If both
external RAM and external PER is enabled, CS0n is mapped to PER
and CS1n is mapped to RAM. This configuration can be used for a
RAM bank split between 2 devices as well as when using both an
external RAM and an external peripheral.
0x3 = ALE with Dual CSn Configuration. EPI0S30 is used as
address latch (ALE), EPI0S27 is used as CS1n, and EPI0S26 is
used as CS0n. Whether CS0n or CS1n is asserted is determined by
the most significant address bit for a respective external address
map.
23-22
RESERVED
R
0x0
21
WRHIGH
R/W
0x0
CS1n WRITE Strobe Polarity This field is used if the CSBAUD bit in
the EPIHB8CFG2 register is enabled.
0x0 = The WRITE strobe for CS1n accesses is WRn (active Low).
0x1 = The WRITE strobe for CS1n accesses is WR (active High).
20
RDHIGH
R/W
0x0
CS1n READ Strobe Polarity This field is used if the CSBAUD bit in
the EPIHB8CFG2 register is enabled.
0x0 = The READ strobe for CS1n accesses is RDn (active Low).
0x1 = The READ strobe for CS1n accesses is RD (active High).