HTU Control Registers
983
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
High-End Timer Transfer Unit (HTU) Module
21.4.1 Global Control Register (HTU GC)
Figure 21-14. Global Control Register (HTU GC) [offset = 00]
31
25
24
23
17
16
Reserved
VBUSHOLD
Reserved
HTUEN
R-0
R/WP-0
R-0
R/WP-0
15
9
8
7
1
0
Reserved
DEBM
Reserved
HTURES
R-0
R/WP-0
R-0
R/WP-0
LEGEND: R/W = Read/Write; R = Read only; WP = Write in privilege mode only; -
n
= value after reset
Table 21-11. Global Control Register (HTU GC) Field Descriptions
Bit
Field
Value
Description
31-25
Reserved
0
Reads return 0. Writes have no effect.
24
VBUSHOLD
Hold the VBUS bus
0
The VBUS is not held.
1
The VBUSHOLD bit holds the bus used to transfer data between the HTU and the N2HET module.
When the BUS_BUSY bit is 0 then the bus is no longer busy. While the bus is held, requests will still be
accepted. They will be acted upon when the VBUSHOLD is 0. Request lost conditions will be detected
and interrupts generated if they are enabled.
23-17
Reserved
0
Reads return 0. Writes have no effect.
16
HTUEN
Transfer Unit Enable Bit
0
The Transfer Unit is disabled.
1
The Transfer Unit is enabled.
The configuration registers and control packets should be set up first before the HTUEN bit is set to 1 to
prevent it from carrying out unintended bus transactions. If the HTUEN bit is cleared to 0 during a frame
is transferred, then the frame will be completed before the HTU is disabled.
The HTUEN bit must be cleared to 0 and the parity functionality must be enabled (by PARITY_ENA)
during the automatic DCP RAM initialization (see Initializing Parity Bits). If HTUEN is 1 when the
initialization is triggered by the system module, then the initialization will not be performed and the HTU
operation is not affected. If a 1 is written to HTUEN during the initialization, then the HTUEN bit will be
set but the HTU will not be enabled before the initialization completes.
Note: If HTU is disabled during a frame transfer, then the ongoing current frame will be
completed before the HTU module is disabled. If enabled again, then the transfer will restart
from the initial frame count for the CP programmed.
15-9
Reserved
0
Reads return 0. Writes have no effect.
8
DEBM
Debug Mode
0
The Transfer Unit is stopped in debug mode.
The HTU will complete the current frame, but not start any new frames. It will also ignore all requests
from the HET and not generate any request lost signals.
1
The Transfer Unit continues operation in debug mode.
Note:
Since the HET has also an "ignore suspend" bit, there a several possibilities for the behavior of
the HET and HTU in suspend mode.
7-1
Reserved
0
Reads return 0. Writes have no effect.
0
HTURES
HTU Software Reset Request
0
Reset request is not issued to the HTU module. Writing a 0 has no effect.
1
Reset request is issued to the HTU module.
Ongoing element transfers will be completed, before resetting the complete HTU module, similar to a
hardware reset. The HTURES bit will also be cleared. The recommended order of operations is:
• Set the software reset bit. This also clears HTUEN.
• Wait for the HTURES bit to clear.
• Configure the HTU registers and packets.
• Set the HTUEN bit to begin operation.