On-Chip Emulation (4 Pins) - Motorola DSP56156 Manual

SRD1 (SSI1 Receive Data) - This input pin receives serial data and transfers the data
to the SSI1 Receive Shift Register. SRD1 may be programmed as a general
purpose I/O pin called PC6 when the SSI1 SRD1 function is not being used.
SCK1 (SSI1 Serial Clock) - This bidirectional pin provides the serial bit rate clock for
the SSI1 interface. SCK1 may be programmed as a general purpose I/O pin
called PC7 when the SSI1 interface is not being used.
SC11 (Serial Control 1) - This bidirectional pin is used by the SSI1 serial interface as
frame sync I/O or flag I/O. SC11 may be programmed as a general purpose I/O
pin called PC8 when the SSI1 is not using this pin.
SC01 (Serial Control 0) - This bidirectional pin is used by the SSI1 serial interface as
frame sync I/O or flag I/O. SC01 may be programmed as a general purpose I/O
pin called PC9 when the SSI1 is not using this pin.
2.9

ON-CHIP EMULATION (4 PINS)

DSI/OS0 (Debug Serial Input/Chip Status 0) - The DSI/OS0 pin, when an input, is the
pin through which serial data or commands are provided to the OnCE control-
ler. The data received on the DSI pin will be recognized only when the DSP has
entered the debug mode of operation. Data must have valid TTL logic levels be-
fore the serial clock falling edge. Data is always shifted into the OnCE serial port
most significant bit (MSB) first. When the DSP is not in the debug mode, the
DSI/OS0 pin provides information about the chip status if it is an output and
used in conjunction with the OS1 pin.
DSCK/OS1 (Debug Serial Clock/Chip Status 1) - The DSCK/OS1 pin, when an input,
is the pin through which the serial clock is supplied to the OnCE. The serial
clock provides pulses required to shift data into and out of the OnCE serial
port. Data is clocked into the OnCE on the falling edge and is clocked out of
the OnCE serial port on the rising edge. When the DSP is not in the debug
mode, the DSCK/OS1 pin provides information about the chip status if it is an
output and used in conjunction with the OS0 pin.
DSO (Debug Serial Output) - The debug serial output provides the data contained
in one of the OnCE controller registers as specified by the last command re-
ceived from the command controller. When idle, this pin is high. When the re-
quested data is available, the DSO line will be asserted (negative true logic) for
four T cycles (one instruction cycle) to indicate that the serial shift register is
ready to receive clocks in order to deliver the data. When the chip enters the
MOTOROLA
ON-CHIP EMULATION (4 PINS)
DSP56156 PIN DESCRIPTIONS 2 - 13