Upgraded to digital on 28.7.2024 after 60 flights. See Martian IV (3 inch, Walksnail) for more details.

Martian IV (3 inch)

Specifications
Frame Realacc Martian IV (3 inch)
FC+ESC HGLRC F4 Zeus AIO 15A
Motors RCX H1304 5000KV
Props HQProp T3x3x3
Emax Avan 3x2.4x3
GemFan 3x1.6x3
Receiver FrSky R-XSR
ImmersionRC Ghost Atto
Camera RunCam Robin with 1.8 mm lens
DVR RunCam Mini FPV DVR Module
VTX AKK FX3
Antenna Realacc UXII Stubby RHCP antenna
Battery Tattu 3S 450 mAh 75C
Turnigy nano-tech 3S 850 mAh 45C
Weight 121 g
164 g (with 3S 450 mAh battery)
M2M 14 cm
Flight time 4-8 minutes

Videos

Notes

  1. Edges of frame pieces should be sanded to avoid wear in wiring
  2. ESC didn't have issues with firmware flashing, came with old firmware that doesn't support turtle mode
  3. FC is essentially 3S max
  4. The FC bundle provided 470uF 25V capacitor was replaced with a 1000uF 35V (both low ESR)
  5. Configuring F.Port with the FC didn't for some reason succeed in providing two way communication resulting in lack of telemetry, RSSI however gets transmitted and shown in OSD (FrSky R-XSR specific)
  6. Power wire needed to be longer than usual due to the short wires used in the Tattu batteries
  7. For power wire management, it's better to have the battery strapped with wires facing forward

DVR control

The RunCam DVR Module has an extra pad marked H/L which can be used to control the recording functionality. Betaflight supports having the recording start from arming (or other action) and then stop once disarmed (or other action). However, this isn't visible in the user interface and requires CLI configuration. Existing Betaflight documentation can be found from https://github.com/betaflight/betaflight/wiki/Pinio-and-PinioBox

The following command set the DVR to start recording when armed and stop when disarmed. As a bonus, there appears to be a 1-2 second delay at least when the recording stops after disarming. 

resource MOTOR 6 NONE
resource SONAR_ECHO NONE
resource PINIO 1 A08
set pinio_config = 129,1,1,1
set pinio_box = 0,255,255,255
save

A08 refers to the S6 wire in the FC multiwire connector. It's mapped in the firmware to motor 6 and sonar echo which both need to first be released before pin i/o can be enabled for gaining DVR control.

Wiring