Register Descriptions
1276
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
External Peripheral Interface (EPI)
Table 17-49. EPI Host-Bus 16 Timing Extension Register (EPIHB16TIME4) Field Descriptions (continued)
Bit
Field
Value
Description
4
WRWSM
CS3 Write Wait State Minus One
This bit is used with the WRWS field in EPIHB16CFG4. This field is not applicable in BURST mode.
0
No change in the number of wait state clock cycles programmed in the in WRWS field in
EPIHB16CFG4 register
1
Wait state value is now:
WRWS - 1
WRWS field is programmed in EPIHB16CFG4
3-1
Reserved
Reserved
0
RDWSM
CS3 Read Wait State Minus One
Used with RDWS field in the EPIHB16CFG4 register. This field is not applicable in BURST mode.
0
No change in the number of wait state clock cycles programmed in the RDWS field of
EPIHB16CFG4
1
Wait state value is now:
RDWS - 1
RDWS field is programmed in EPIHB16CFG4
17.11.37 CEPIRTWCFG Register
Figure 17-64. CEPIRTWCFG Register
31
4
3
1
0
KEY
Reserved
GRAB
R/W-0
R-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 17-50. CEPIRTWCFG Register Field Descriptions
Bit
FiKEY
Value
Description
31-4
KEY
This field should have value of “0x9EDCB4A” to enable write into the GRAB bit. During every write
to GRAB bit this field must have a valid value, hence the user always has to do a 32-bit write to
change the GRAB bit.
3-1
Reserved
Reserved
0
GRAB
Grabs the access for control subsystem (C28x-CPU/C28x-DMA). This bit gets reset to ‘0’ when
TIMEOUT bit in CEPISTATUS register is set.
0
RTW feature is disabled. All the accesses to the external device via EPI are arbitrated based on
round robin scheme.
1
RTW feature is enabled. All the accesses from the Master subsystem (M3/uDMA) to the external
device via EPI are stalled until this bit is set to ‘1’.
17.11.38 CEPIRTWCNT Register
Figure 17-65. CEPIRTWCNT Register
31
0
EPIRTWCNT
R-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 17-51. CEPIRTWCNT Register Field Descriptions
Bit
FiKEY
Value
Description
31-0
EPIRTWCNT
This is a free running counter which counts up for every cycle of C28x CPU CLK. This counter gets
enabled when the GRAB bit in the CEPIRTWCFG registers gets set to ‘1’. This counter gets reset
to 0x0 when GRAB bit in CEPIRTWCFG registers get reset to ‘0’.