In-circuit communication configuration
ST7-EMU3 series emulator
Figure 25.
ICC interface
Isolation of ICCDATA and ICCCLK pins
As soon as the emulator’s ICC Add-on is plugged into the application board the ICCDATA
and ICCCLK pins must not be used by other application devices, even if an ICC session is
not in progress. If the application uses these pins as inputs, isolation such as a serial
resistor must be implemented to prevent other application devices from forcing a signal on
either of these pins. The application board must not drive current in excess of 1mA.
If the ICCDATA and ICCCLK pins are only used as outputs by the application, no signal
isolation is necessary. For ST7 without an ICCSEL pin, during normal operation the ICCCLK
pin must be pulled-up internally or externally (10K
Ω
pull-up required in noisy environments).
This is to avoid entering ICC mode unintentionally during a reset.
Table 3.
ICC connection requirements
ST7 pin
Description
Connects to ICC
ICCDATA
ICC input/output serial data pin
ICCDATA
ICCCLK
ICC output serial clock pin
ICCCLK
RESET
Device reset
ICCRESET
ICCSEL/VPP
Programming voltage
ICCSEL/VPP
OSC1 or OSCIN
Main clock input for external
ICCOSC
VDD
Device power supply
Not connected
VSS
Device power supply (ground)
GND