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6.25 IEEE 1149.1 JTAG
6.25.1
JTAG Peripheral Register Description(s) – JTAG ID Register
TMS320DM6443
Digital Media System-on-Chip
SPRS282E–DECEMBER 2005–REVISED MARCH 2007
The JTAG
(1)
interface is used for BSDL testing and emulation of the DM6443 device.
The DM6443 device requires that both TRST and RESET be asserted upon power up to be properly
initialized. While RESET initializes the device, TRST initializes the device's emulation logic. Both resets
are required for proper operation.
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, DM6443 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.
IEEE Standard 1149.1-1990 Standard-Test-Access Port and Boundary Scan Architecture.
(1)
Table 6-106. JTAG ID Register
HEX ADDRESS RANGE
ACRONYM
REGISTER NAME
COMMENTS
Read-only. Provides 32-bit
JTAG ID of the device.
0x01C4 0028
JTAGID
JTAG Identification Register
The JTAG ID register is a read-only register that identifies to the customer the JTAG/Device ID. For the
DM6443 device, the JTAG ID register resides at address location 0x01C4 0028. The register hex value for
DM6443 is: 0x0B70 002F. For the actual register bit names and their associated bit field descriptions, see
Figure 6-74
and
Table 6-107
.
31-28
27-12
11-1
0
VARIANT (4-Bit)
PART NUMBER (16-Bit)
MANUFACTURER (11-Bit)
LSB
R-0000
R-1011 0111 0000 0000
R-0000 0010 111
R-1
LEGEND: R = Read, W = Write, n = value at reset
Figure 6-74. JTAG ID Register Description - DM6443 Register Value - 0xXB70 002F
Peripheral and Electrical Specifications
216
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