Motorola USB08 - Manual (Page 34)

Designer Reference Manual USB08 Evaluation Board
34 Hardware Description MOTOROLA
Hardware Description
is the first jumper of the jumper block JP1, and it must be set in order to
apply high voltage to IRQ.
If the monitor mode interface is not needed or if it disturbs the
investigation of certain circuit configurations, it can be uncoupled
completely from the MCU core. For this purpose:
• All jumpers of jumper block JP1 have to be removed.
• RS232 receiver IC2 has to be removed from the socket.
Using the X2 plug connector, the monitor mode interface is connected to
the PC. The monitor mode cable consists of:
• A flat cable with a Berg connector (2
×
5 pin, crimping connection)
on the device side
• A sub-D9 connector (crimping connection) on the PC side
A one-to-one connection is implemented by this cable configuration, as
shown in
Table 2-2 .
The MC68HC908JB8 logic levels are based on the operating voltage
V
CC
(3.3 V); however, the transceiver IC2 works with V
DD
(5 V). The
adjustment of the logic levels according to specification is not difficult
(refer to the individual integrated circuit data sheets). The Schottky
diode, D6, enables the push/pull exit R1OUT to be wired-OR capable
and prevents a feeding of levels beyond the tolerance limit of the input
PTA0.
Table 2-2. Monitor Mode Cable Pin Configuration
X2 Pin USB08 Monitor PC RS232 Sub-D 9 Pin
3 T1OUT RxD 2
5 R1IN TxD 3
9 GND GND 5