SPRS457E
– MARCH 2009 – REVISED JUNE 2011
6.27 IEEE 1149.1 JTAG
The JTAG(1) interface is used for BSDL testing and emulation of the device.
The 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, the device includes an internal pulldown (PD) 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 power up and externally
drive TRST high before attempting any emulation or boundary scan operations. Following the release of
RESET, the low-to-high transition of TRST must be "seen" to latch the state of EMU1 and EMU0. The
EMU[1:0] pins configure the device for either Boundary Scan mode or Emulation mode. For more detailed
information, see the terminal functions section of this data sheet.
6.27.1 JTAG Register Description(s)
Table 6-105 shows the DEVICE ID register (which includes the JTAG ID related information), its
corresponding acronym, and the device memory location. For more details on the DEVICE ID register bit
fields, see the TMS320DM36x DMSoC ARM Subsystem Reference Guide (literature number
SPRUFG5).Table 6-106. DEVICE ID Register
HEX ADDRESS RANGE
ACRONYM
REGISTER NAME
COMMENTS
Read-only. Provides 32-bit
0x01C4 0028
DEVICEID
JTAG Identification Register
JTAG ID of the device.
(1)
IEEE Standard 1149.1-1990 Standard-Test-Access Port and Boundary Scan Architecture.
The DEVICE ID register is a read-only register that identifies to the customer the JTAG/Device ID. For the
device, the DEVICE ID register resides at address location 0x01C4 0028. The register hex value for the
device is: 0xXB70 002F where 'X' denotes the silicon revision of the device. For more details on the silicon
revision, see the TMS320DM365 DMSoC Silicon Errata (literature number
SPRZ294).Copyright
2009–2011, Texas Instruments Incorporated
Peripheral Information and Electrical Specifications
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