Texas Instruments TMS320DM355 사용자 설명서
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PRODUCT PREVIEW
5.18 IEEE 1149.1 JTAG
TMS320DM355
Digital Media System-on-Chip (DMSoC)
Digital Media System-on-Chip (DMSoC)
SPRS463A – SEPTEMBER 2007 – REVISED SEPTEMBER 2007
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 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.
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.
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.
correctly. Other boundary-scan instructions work correctly independent of current state of RESET.
For maximum reliability, 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.
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.
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 intialize the device after powerup 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.
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.
(1)
IEEE Standard 1149.1-1990 Standard-Test-Access Port and Boundary Scan Architecture.
148
Peripheral Information and Electrical Specifications