Technical information

6
Section 2 User System Interface
All user system interface signals are directly connected to the MCU in the E6000 with no buffering
except for those listed below which are connected to the MCU through control circuits:
•
NMI
•
/RES
•
MD2, MD1, MD0
•
/STBY
•
XTAL
•
EXTAL
2.1 Signal Protection
All user system interface signals are protected from over- or under-voltage by use of diode arrays
except for the AVcc and Vref.
Pull-up resistors are connected to the port signals except for the analog port signals.
The Vcc pins (except for the AVcc pin) at the head of the user system interface cable are
connected together. The E6000 monitors the voltage level of the Vcc pins and displays the power-
supply status in the Platform sheet in the System Status Window. Pin 1, which will be a V
CL
pin or
Vcc pin, is not connected.
If the user system interface cable is not connected to the user system, the Vcc pin of the user
system is 3.3V.
2.2 User System Interface Circuits
The interface circuit between the MCU in the E6000 and the user system has a signal delay of
about 8 ns due to the user system interface cable and it includes pull-up resistors. Therefore, high-
impedance signals will be pulled up to the high level. When connecting the E6000 to a user
system, adjust the user system hardware to compensate for propagation delays.
The following diagrams show the interface signal circuits.