HAB Bounder, a self-contained balloon termination (aka cut-down device), now features an external trigger. It will accept an activation signal from a flight computer, satellite modem, or radio link. Once the command is received, HAB Bounder will initiate its independent activation sequence that ensures the line it is attached to is completely and rapidly severed.
- Off: all signals into the external trigger port are completely ignored
- Rising: the HAB Bounder pulls the external trigger line low with a 10K resistor and triggers when an external signal pulls the line high
- Falling: the HAB Bounder pulls the external trigger line high with a 10K resistor and triggers when an external signal pulls the line low
The external trigger setting is configured by the following line in the CONFIG.TXT file on the HAB Bounder’s micro-SD card. It is present in firmware versions 11 and newer. [EXT=OFF], External Trigger (1=Falling 2=Rising)
Noise Rejection
Spurious noise is rejected by requiring the external trigger line to be held low or high for at least 75 ms. After 75 ms, the line state does not effect the HAB Bounder. This permits relays, trip-wires, and other rudimentary control methods to be utilized.
Input Signal
The external trigger input is protected with both a resettable fuse and a zener diode to provide the most robust interface possible. For the rising trigger, voltages between 2.7 VDC and 5.5 VDC can be used. For the falling trigger, a high-impedance GPIO pin or external open-collector circuit can be used.
The external trigger utilizes a minimal 2-wire interface through a Molex Pico-Flex connector. A short pigtail wiring harness is provided (approx. 150 mm). Longer lengths or a custom wiring harness are available upon request. Activation currents are <5 mA, so long runs of small wire are permitted.
HAB Bounder’s External Trigger has been used with
- PixHawk 2
- Teensy 3.2
- Nordic Semiconductor nRF52832
- N-Channel MOSFET