Datasheet

TRST

C28x

Core

TCK/GPIO38

TCK

XCLKIN

GPIO38_in

GPIO38_out

TDO

GPIO37_out

TDO/GPIO37

GPIO37_in

TMS

TMS/GPIO36

GPIO36_out

GPIO36_in

TDI

TDI/GPIO35

GPIO35_out

GPIO35_in

TRST

=0:JTAGDisabled(GPIOMode)

=1:JTAGMode

TRST

TMS320F28027, TMS320F28026, TMS320F28023, TMS320F28022

TMS320F28021, TMS320F28020, TMS320F280200

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SPRS523J –NOVEMBER 2008–REVISED OCTOBER 2013

4.8 JTAG Port

On the 2802x device, the JTAG port is reduced to 5 pins (TRST, TCK, TDI, TMS, TDO). TCK, TDI, TMS

and TDO pins are also GPIO pins. The TRST signal selects either JTAG or GPIO operating mode for the

pins in Figure 4-11. During emulation/debug, the GPIO function of these pins are not available. If the

GPIO38/TCK/XCLKIN pin is used to provide an external clock, an alternate clock source should be used

to clock the device during emulation/debug since this pin will be needed for the TCK function.

NOTE

In 2802x devices, the JTAG pins may also be used as GPIO pins. Care should be taken in

the board design to ensure that the circuitry connected to these pins do not affect the

emulation capabilities of the JTAG pin function. Any circuitry connected to these pins should

not prevent the emulator from driving (or being driven by) the JTAG pins for successful

debug.

Figure 4-11. JTAG/GPIO Multiplexing

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Product Folder Links: TMS320F28027 TMS320F28026 TMS320F28023 TMS320F28022 TMS320F28021

TMS320F28020 TMS320F280200