MAX-7 / NEO-7 - Hardware Integration Manual
UBX-13003704
-
R09
Production Information
Design
Page
28 of 52
Figure 23: Module design with active antenna, external supply
3.4.3.3
Antenna supervision open circuit detection (OCD) (MAX-7W)
The open circuit detection circuit uses the current flow to detect an open circuit in the antenna. Calculate the
threshold current using Equation 1.
Figure 24: Schematic of open circuit detection
RF
Vcc
Rbias
R
R
R
I
_
3
2
2
Equation 1: Calculation of threshold current for open circuit detection
Antenna open circuit detection (OCD) is not activated by default. It can be enabled by the UBX-CFG-ANT
message. This configuration can be sent to the receiver at every startup or can be saved permanently in flash.
MAX-7W does not have a dedicated
AADET_N
pin. The
AADET_N
pin can be made available on the
EXINT
pin.
To do so, the following command must be sent once and stored permanently to the receiver:
“B5 62 06 41 0C 00 00 00 03 1F 06 5F 8B B1 FF F6 B7 FF C1 D7”.
To enable the OCD feature, the following command must be sent to the receiver at every startup:
“B5 62 06 13 04 00 1F 00 F0 B5 E1 DE”.
The
AADET_N
pin then has High = "ANTSTATUS=OPEN", Low = "ANTSTATUS=OK",.
