1.4.1.2 Choosing JTAG or GPIO Functionality
The TRST signal selects the functionality of the JTAG signals, in combination with the JTAGDIS bit in the
JTAGDEBUG register as follows.
TRST
JTAGDIS bit
JTAG Port Mode
0
X
GPIO mode enabled, JTAG port disabled
1
0
JTAG port enabled (GPIOs should be configured as inputs)
1
1
GPIO mode enabled, JTAG port disabled
The JTAGDEBUG register is shown and described below.
Figure 1-61. JTAGDEBUG Register (Address 0x702A, EALLOW protected)
15
1
0
Reserved
JTAGDIS
R-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 1-55. JTAGDEBUG Register Field Descriptions
Bits
Field
Value
Description
15-1
Reserved
Any writes to these bits must always have a value of 0.
0
JTAGDIS
JTAG Port Disable Bit: This bit enables/disables the JTAG port. When disabled, the JTAG pins
can be used as GPIOs:
0
JTAG Port Enabled
1
JTAG Port Disabled (GPIO Mode)
This bit is reset by TRST. The bit is forced to "0" when TRST is "0". When TRST is "1",
then JTAGDIS bit can be modified by CPU.
Note:
Ensure no contention with the debug probe
signals when JTAGDIS=1
System Control and Interrupts
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
TMS320x2806x Microcontrollers
111
Copyright © 2022 Texas Instruments Incorporated
Summary of Contents for TMS320 2806 Series
Page 2: ......