EPI Registers
1143
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
External Peripheral Interface (EPI)
Table 16-22. EPIHB16CFG2 Register Field Descriptions
Bit
Field
Type
Reset
Description
31-28
RESERVED
R
0x0
27
CSCFGEXT
R/W
0x0
Chip Select Extended Configuration.
This field is used in conjunction with CSCFG, to extend the chip
select options, and ALE format. The values 0x0 through 0x3 are
from the CSCFG field. The CSCFGEXT bit extends the values to
0x7.
0x0 = CSCFG bit field is used in chip select configuration.
0x1 = The CSCFG bit field is extended with CSCFGEXT
representing the MSB.
The possible chip select configurations (CS CSCFG
encodings) when the CSCFGEXT bit is enabled are:
0x0 = ALE Configuration. EPI0S30 is used as an address latch
(ALE). The ALE signal is generally used when the address and data
are muxed (MODE field in the EPIHB16CFG 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 (MODE field in the EPIHB16CFG 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 the most significant address bit for a respective
external address map. 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.
0x4 = ALE with Single CSn Configuration. EPI0S30 is used as
address latch (ALE) and EPI0S27 is used as CSn.
0x5 = Quad CSn Configuration. EPI0S30 is used as CS0n and
EPI0S27 is used as CS1n. EPI0S34 is used as CS2n and EPI0S33
is used as CS3n.
0x6 = ALE with Quad CSn Configuration. EPI0S30 is used as ALE,
EPI0S26 is CS0n, and EPI0S27 is used as CS1n. EPI0S34 is used
as CS2n and EPI0S33 is used as CS3n.
0x7 = Reserved