User`s guide

NE-4100 Series Serial Command Mode User’s Guide
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5
5
Chapter 5 Entering Serial Command Mode
In this chapter, we explain how to enter Serial Command Mode.
Trigger Type
There are two types of trigger, HW (Hardware) and SW (Software).
HW Trigger
! HW Trigger is passed through the GPIO 0 pin.
!
Pull GPIO 0 as low to trigger (the pin will normally pull high).
Note that the low level trigger must persist for more than 200 ms to qualify as a valid trigger.
SW Trigger
! The Trigger is activated when 3 user-defined characters are detected.
!
See the previous chapter for an explanation of how to configure the SW trigger characters.
1.
The time interval between characters must be less than 20 ms.
2.
When the SW Trigger is enabled, the highest achievable data transmission rate will be
reduced from 234000 bps to 55000 bps. This is because all data received through serial
port 0 will be parsed. In other words, the system must continuosly check the serial port
data for the SW Trigger characters.