User`s manual

3-6 Universal Command Converter Motorola
Host Computer Hardware
There are three input control bits in the middle-order byte of Port B data word that
represent the HOST_ACK, HOST_REQ, and INT_ACK. These signals are sent from the
host computer for reading and writing data. INT_ACK informs the monitor program that
the host computer has received its service request and is ready to communicate.
HOST_BRK
is a wired-OR control line. HOST_BRK is used by the command converter
to inform the host computer whenever the target DSP has entered the Debug mode of
operation for non-JTAG devices only. Since more than one command converter may be
started for a user debug session, more than one may hold HOST_BRK
active low at one
time. Once this signal is asserted it may only be deasserted by the host computer or by a
command converter reset.
3.1.5 Command Converter Interface Connector
The target application board must have a 14-pin connector to interface to the command
converter controller. This interface comprises nine signals and three ground connections
on a 7-row × 2-column male pin header, which are spaced on 1/10 inch centers as
illustrated in Figure 3-4 on page 3-7.
Since the target system will have a resident reset circuit, it is recommended to have an
AND gate in series with the CC_RESET
signal. This will insure that the target DSP will
be reset with a valid V
OL
level from either the target reset circuit or from the command
converter. The pull-down resistors are to insure that no false signals are propagated to the
JTAG/OnCE circuit when the test data input/debug serial input (TDI/DSI) and test data
clock/debug serial clock (TCK/DSCK) lines are active. The test data out/debug serial
output (TDO/DSO) pullup is to insure that the Debug Acknowledge signal from the OnCE
circuit is deasserted. The debug request (DR
) pullup is to insure that the command
converter controls when the target DSP is placed into its Debug mode.