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EPI Registers
1152
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
External Peripheral Interface (EPI)
16.5.14 EPISTAT Register (Offset = 0x60) [reset = 0x0]
EPI Status (EPISTAT)
This register indicates which non-blocking read register is currently active; it also indicates whether the
external interface is busy performing a write or non-blocking read (it cannot be performing a blocking read,
as the bus would be blocked and as a result, this register could not be accessed).
This register is useful to determining which non-blocking read register is active when both are loaded with
values and when implementing sequencing or sharing.
This register is also useful when canceling non-blocking reads, as it shows how many values were read by
the canceled side.
EPISTAT is shown in
and described in
Return to
Figure 16-43. EPISTAT Register
31
30
29
28
27
26
25
24
RESERVED
R-0x0
23
22
21
20
19
18
17
16
RESERVED
R-0x0
15
14
13
12
11
10
9
8
RESERVED
XFFULL
R-0x0
R-0x0
7
6
5
4
3
2
1
0
XFEMPTY
INITSEQ
WBUSY
NBRBUSY
RESERVED
ACTIVE
R-0x0
R-0x0
R-0x0
R-0x0
R-0x0
R-0x0
Table 16-27. EPISTAT Register Field Descriptions
Bit
Field
Type
Reset
Description
31-9
RESERVED
R
0x0
8
XFFULL
R
0x0
External FIFO Full This bit provides information on the XFIFO when
in the FIFO sub-mode of the Host Bus n mode with the XFFEN bit
set in the EPIHBnCFG register.
The EPI0S26 signal reflects the status of this bit.
0x0 = The external device is not gating the clock.
0x1 = The XFIFO is signaling as full (the FIFO full signal is
high).Attempts to write in this case are stalled until the XFIFO full
signal goes low or the counter times out as specified by the
MAXWAIT field.
7
XFEMPTY
R
0x0
External FIFO Empty This bit provides information on the XFIFO
when in the FIFO sub-mode of the Host Bus n mode with the XFEEN
bit set in the EPIHBnCFG register.
The EPI0S27 signal reflects the status of this bit.
0x0 = The external device is not gating the clock.
0x1 = The XFIFO is signaling as empty (the FIFO empty signal is
high).Attempts to read in this case are stalled until the XFIFO empty
signal goes low or the counter times out as specified by the
MAXWAIT field.
6
INITSEQ
R
0x0
Initialization Sequence
0x0 = The SDRAM interface is not in the wakeup period.
0x1 = The SDRAM interface is running through the wakeup period
(greater than 100 microseconds).If an attempt is made to read or
write the SDRAM during this period, the access is held off until the
wakeup period is complete.