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TMS320C6748
www.ti.com
SPRS590G – JUNE 2009 – REVISED JANUARY 2017
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TMS320C6748
Peripheral Information and Electrical Specifications
Copyright © 2009–2017, Texas Instruments Incorporated
While both TRST and RESET need to be asserted upon power up, only RESET needs to be released for
the device to boot properly. TRST may be asserted indefinitely for normal operation, keeping the JTAG
port interface and device's emulation logic in the reset state.
TRST only needs to be released when it is necessary to use a JTAG controller to debug the device or
exercise the device's boundary scan functionality. Note: TRST is synchronous and
must
be clocked by
TCK; otherwise, the boundary scan logic may not respond as expected after TRST is asserted.
RESET must be released only in order for boundary-scan JTAG to read the variant field of IDCODE
correctly. Other boundary-scan instructions work correctly independent of current state of RESET.
For maximum reliability, the device includes an internal pulldown (IPD) on the TRST pin to ensure that
TRST will always be asserted upon power up and the device's internal emulation logic will always be
properly initialized.
JTAG controllers from Texas Instruments actively drive TRST high. However, some third-party JTAG
controllers may not drive TRST high but expect the use of a pullup resistor on TRST.
When using this type of JTAG controller, assert TRST to initialize the device after powerup and externally
drive TRST high before attempting any emulation or boundary scan operations.
6.34.4.1
JTAG Peripheral Register Description(s) – JTAG ID Register (DEVIDR0)
Table 6-145. DEVIDR0 Register
BYTE ADDRESS
ACRONYM
REGISTER DESCRIPTION
COMMENTS
0x01C1 4018
DEVIDR0
JTAG Identification Register
Read-only. Provides 32-bit
JTAG ID of the device.
The JTAG ID register is a read-only register that identifies the JTAG/Device ID. For the device, the JTAG
ID register resides at address location 0x01C1 4018. The register hex value for each silicon revision is:
•
0x0B7D 102F for silicon revision 1.x
•
0x1B7D 102F for silicon revision 2.x
For the actual register bit names and their associated bit field descriptions, see
Figure 6-88
and
Table 6-
146
.
Figure 6-88. JTAG ID (DEVIDR0) Register Description - Register Value
31-28
27-12
11-1
0
VARIANT (4-Bit)
PART NUMBER (16-Bit)
MANUFACTURER (11-Bit)
LSB
R-xxxx
R-1011 0111 1101 0001
R-0000 0010 111
R-1
LEGEND: R = Read, W = Write, n = value at reset
Table 6-146. JTAG ID Register Selection Bit Descriptions
BIT
NAME
DESCRIPTION
31:28
VARIANT
Variant (4-Bit) value
27:12
PART NUMBER
Part Number (16-Bit) value
11-1
MANUFACTURER
Manufacturer (11-Bit) value
0
LSB
LSB. This bit is read as a "1".