TMS320F datasheet(355/389 Pages) TI

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Emulation Design Considerations

C-20

C.8.3 Using Emulation Pins

The EMU0/1 pins of TI devices are bidirectional, 3-state output pins. When in

an inactive state, these pins are at high impedance. When the pins are active,

they provide one of two types of output:

- Signal event. The EMU0/1 pins can be configured via software to signal

internal events. In this mode, driving one of these pins low can cause

devices to signal such events. To enable this operation, the EMU0/1 pins

function as open-collector sources. External devices such as logic analyz-

ers can also be connected to the EMU0/1 signals in this manner. If such

an external source is used, it must also be connected via an open-collector

source.

- External count. The EMU0/1 pins can be configured via software as totem-

pole outputs for driving an external counter. If the output of more than one

device is configured for totem-pole operation, then these devices can be

damaged. The emulation software detects and prevents this condition.

However, the emulation software has no control over external sources on

the EMU0/1 signal. Therefore, all external sources must be inactive when

any device is in the external count mode.

TI devices can be configured by software to halt processing if their EMU0/1

pins are driven low. This feature combined with the signal event output, allows

one TI device to halt all other TI devices on a given event for system-level de-

bugging.

If you route the EMU0/1 signals between multiple boards, they require special

handling because they are more complex than normal emulation signals.

Figure C–11 shows an example configuration that allows any processor in the

system to stop any other processor in the system. Do not tie the EMU0/1 pins

of more than 16 processors together in a single group without using buffers.

Buffers provide the crisp signals that are required during a RUNB (run bench-

mark) debugger command or when the external analysis counter feature is

used.

TMS320F Datasheet(PDF) 355 Page - Texas Instruments