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EPI Registers
1134
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
External Peripheral Interface (EPI)
Table 16-19. EPIHB16CFG Register Field Descriptions (continued)
Bit
Field
Type
Reset
Description
17
RDCRE
R/W
0x0
PSRAM Configuration Register Read Enables read of PSRAM
configuration registers.
With the RDCRE set, the next access is a read of the PSRAM's
Configuration Register (CR).
This bit self clears once the read-enabled CRE access is complete.
The address for the CRE access is located at EPIHBPSRAM
[19:18].
The read data is returned on EPIHBPSRAM
[15:0].
0x0 = No Action.
0x1 = Start CRE read transaction for CS0n.
16
BURST
R/W
0x0
Burst Mode Burst mode must be used with an ALE-enabled
interface.
Burst mode must be used with ADMUX, which is configured by the
MODE field in the EPIHB16CFG register.
Burst mode is optimized for word-length accesses.
0x0 = Burst mode is disabled.
0x1 = Burst mode is enabled for CS0n or single chip access.
15-8
MAXWAIT
R/W
0xFF
Maximum Wait This field defines the maximum number of external
clocks to wait while an external FIFO ready signal is holding off a
transaction (FFULL and FEMPTY).
When this field is clear, the transaction can be held off forever
without a system interrupt.
When the MODE field is configured to be 0x3 and the BLKEN bit is
set in the EPICFG register, enabling HB16 mode, this field defaults
to 0xFF.
7-6
WRWS
R/W
0x0
Write Wait States This field adds wait states to the data phase of
CS0n (the address phase is not affected).
The effect is to delay the rising edge of WRn (or the falling edge of
WR).
Each wait state adds 2 EPI clock cycles to the access time.
The WRWSM bit EPIHB16TIME register can decrease the number
of wait states by 1 EPI clock cycle for greater granularity.
This field is not applicable in BURST mode.
This field is used in conjunction with the EPIBAUD register.
0x0 = Active WRn is 2 EPI clocks.
0x1 = Active WRn is 4 EPI clocks.
0x2 = Active WRn is 6 EPI clocks.
0x3 = Active WRn is 8 EPI clocks.
5-4
RDWS
R/W
0x0
Read Wait States This field adds wait states to the data phase of
CS0n (the address phase is not affected).
The effect is to delay the rising edge of RDn/Oen (or the falling edge
of RD).
Each wait state adds 2 EPI clock cycles to the access time.
The RDWSM bit in the EPIHB16TIME register can decrease the
number of wait states by 1 EPI clock cycle for greater granularity.
This field is not applicable in BURST mode.
This field is used in conjunction with the EPIBAUD register
0x0 = Active RDn is 2 EPI clocks.
0x1 = Active RDn is 4 EPI clocks.
0x2 = Active RDn is 6 EPI clocks.
0x3 = Active RDn is 8 EPI clocks.
3
RESERVED
R
0x0
2
BSEL
R/W
0x0
Byte Select Configuration This bit enables byte select operation.
If BSEL = 0, byte accesses cannot be executed.
0x0 = No Byte SelectsData is read and written as 16 bits.
0x1 = Enable Byte SelectsTwo EPI signals function as byte select
signals to allow 8-bit transfers. See for details on which EPI signals
are used.