RC, photos & tech


ZMR250 v2 Build – Part 8 – FC Power Connection

Initially I hooked up power to the Flight Controller from the 'BEC' and 'GND' pins next to the FC but this didn't work..... the reason..... the BEC pin is designed to take 5V from the ESC BEC which of course I don't have because I'm using the LittleBee 20A ESCs which don't have a BEC.

The alternative is to use the 5V regulator built into the PDB. Oscar Liang's web page has some excellent diagrams showing the layout and connections of the ZMR250 v2 PDB.

ZMR250 V2 Build Log – Mini Quad with PDB

Tagged as: , No Comments

ZMR250 Build – Part 7 – Buzzer Connection

The early versions of the Banggood SP Racing Flight Controller have an issue where the buzzer connections don't work. To get around it is an easy fix and just requires soldering a couple of wires from the bottom side of the FC to the buzzer connections.




ZMR250 Build – Part 5 – EMAX 12A ESC Update

In this video I look at updating the EMAX 12A ESCs with a direct connection to BLHeli via an Arduino Uno (as opposed to going via the flight control board). Initial reading of the supported SiLabs ESCs documents indicated it wasn't going to be straightforward. After some Googling I found the video below which shows  step by step instructions how to do this.

The alternative would be just to buy one of the EMAX $10 programming cards which I guess is simple enough but then I'll never be able to do BLHeli firmware updates plus I like being able to use the BLHeli to check and set the ESC parameters.

After going through the process of soldering on a wire to each of the four ESCs and updating to the latest BLHeli, I found these particular ESCs don't support damped (damping?) light / active braking which is a bit of a bummer so I ordered four Little Bee ESCs instead. It would be interesting to compare between the two types of ESCs when it comes to flying but I'm not sure I'm up for the hassle of swapping out the ESCs.





Tagged as: , , No Comments

ZMR250 Build – Part 2 – Power & ESC Check

In this video I hook up power to the fpvmodel PDB and to the EMAX 12A ESC. I'm trying to decide whether to solder the Sunnysky motors directly to the ESC or to the ESC leads. Removing the heatshrink from the ESC shows what looked like dodgy solder job touching the pins of the ICs. I wondered if they were going to work at all. After hooking up power and successfully testing them, I decided to use the ESC leads to connect to the motors for two reasons;

  1. Unlike other ESCs that have the three points at the end of the ESC to connect to the motor wires, these EMAX 12A ESCs have them along the middle of the board which means the wires would be staggered (different lengths).
  2. The connections are inbetween ICs and some of them make contact with the legs of the ICs. I don't want to break the connections with a messy soldering job.


ZMR250 Build – Part 4 – FC Firmware Flash

In this video I hook up the SP F3 Flight Controller to update the firmware via the Cleanflight Configurator app. Even though I've done this a heap of times I still manage to make mistakes doing the firmware flash. Some of the mistakes include;

  1. Wrong settings in the app.
  2. I'm so used to flashing my Naze32 rev5/6 boards, I uploaded the wrong Betaflight firmware (now I'm using the SP F3 FC).
  3. Leaving the "flash on connect" setting active in the configurator without realising it and interrupting a firmware update before it finished.

I remember reading somewhere that "you can't brick these boards" because the bootloader is stored in ROM. Just short the boot pins and flash again. Lucky for me the boards are resilient in this way as I've had to use the bootloader pins a number of times.

I never did get the 4way BLHeli firmware update to work via the FC board so in the end I gave up on that option and looked at updating the ESCs with a direct connection to the board. More on that in the next video.

Tagged as: No Comments

ZMR250 Build – Part 3 – Motor & ESC Test

In this video I let Grace take the controls of the motor and test it mounted to the 4mm arm. The first thing I noticed was the motor stuttered at low throttle. Looking closely at the bottom of the motor mount I noticed the circlip on the motor shaft was stuck against the side of the hole cut through the arm for the motor shaft. For this test I simply centred the motor so the circlip spins freely however I think the better long term solution is to enlarge the hole.

Gracie gets a chance to check out the running lights on the PDB and quite likes them.


Tagged as: , No Comments

ZMR250 Build – Part 1 – Parts List

The purpose of this build log is to document the process of building a ZMR250 quadcopter complete with FPV and telemetry. My experience building a previous ZMR250 has been that simple problems like outdated firmware can cause major headaches and heaps of Google searching / forum reading to find the solution. The plan here is to document each step no-matter how seemingly simple it may seem


ZMR250 V2.1 Mini Quad Frame Kit w/PDB Special Edition -

Mini DC-DC 12V Voltage Step-down Regulator Module



FrSky X4RSB 3/16 Channel Telemetry Receiver

Upgrade NAZE32 SP Racing F3 Flight Control Acro 6 DOF/Deluxe 10 DOF for Multicopter

Eachine 700TVL ET25 5.8G 32CH 25mW 7-24V Super Light Transmitter

MICRO MinimOSD Minim OSD Mini OSD W/ KV Team MOD For Naze32 Flight Controller



New DALprop 2 Pairs 5045BN Bullnose Propellers for Racing

Emax BLHeli Series 12A ESC For Quadcopter RC250 Mini200 QAV250

SunnySky X2204S-16 2300kV Brushless Multirotor Motor

Foxeer XAT600M DC5V-22V 600tvl Sony Super HAD CCD FPV Camera

5.8Ghz Circular-polarized Omni Cloud Spirit Tx Antenna



Making an NDVI Camera

Following the guide here;

I'm making a camera capable of taking near-infrared photos. The theory being that with some image processing, a photo taken with an NDVI camera can show where plants / vegetation is growing well compared to where it's not growing so well.

The hardest part involves taking a camera apart, removing the infrared filter and putting it all back together in a working state. A couple of cheapy cameras off eBay help with the practice. I destroyed the first camera but go the second going ok. Here's a photo of the camera in pieces and the image sensor.





The photos below show "normal", "near infrared" and "NDVI" versions of the same photo;










Tagged as: , , No Comments

Character Set Update – MinimOSD

The problem:

The on screen display (OSD) characters from the Hobbyking Minim OSD v1.1 appear garbled.

video and at seven minutes in he explains that both sides of the board need to be powered for the character update to work. I was thinking "what the hell, how is this not stated on the instructions page!"  Actually it is, right here in black and white. The point is, if your Minim OSD lights don't look like the picture below, the character set update probably ain't going to work.

minim OSD ready for character set update

minim OSD ready for character set update





Multirotor loops and rolls just got easier with OpenPilot

With the latest release of the OpenPilot software version 14.01  come two new features (among others) that when combined, make flipping and rolling a multirotor (MR) even easier. A new flight mode called "Rattitude"  is a hybrid of the self levelling "Attitude" and the more aerobatic 'Rate' mode. In "Rattitude" mode as the control stick on the transmitter moves out from the centre, the flight mode of the craft changes from 100% Attitude through to 100% Rate with varying degree of mixture in between. The effect means that letting go of the sticks means the MR will return to self levelling (ie Attitude mode) but you can still throw it around as the control sticks  move out from centre, you get the aerobatic response of Rate mode.

Normally you would have to flick a switch to go from Attitude to Rate. In Attitude mode, because it's always trying to self level, to maintain forward flight you have to constantly be holding the stick forward. It feels like you're fighting it to a degree for the whole flight. Also Attitude mode limits the maximum angle of pitch and roll so if you try to roll in Attitude mode, you'll roll to the angle defined as the maximum and not go any further around.
In Rate mode, it goes where you point it. If you roll to 45 degrees, the MR will attempt to hold that angle until you tell it otherwise. Rate mode can be intimidating for the novice pilot as the safety net of self levelling is removed and depending on the settings, Rate mode can fill quite 'slippery' if you're not used to it.

The other new feature in 14.01 is Cruise Control  which from my limited reading of the topic attempts to maintain a steady altitude when the MR is turning or banking by slightly increasing the rpm to counter the slight decrease in lift). With Cruise Control comes a 'Max Angle' parameter that when set to 90 degrees, combined with Rattitude mode, means that as the MR rolls past 90 degrees, it automatically spins down the motors. That means the part of the roll when the MR is passing through the inverted (ie the props would normally be pulling it to the ground), the motors are automatically shut down which seems to make for a much tighter roll.

From personal experience I went from rolling and flipping with at least 10m height to doing the same at maybe head height. The first time I tried this combination it was quite weird to hear the motors shut down as it passed through the 90 degree vertical point but they came back up a few milliseconds later. Posts in the OpenPilot forum suggest that setting the Cruise Control Max Angle (CCMA) to 80 degrees and the degrees / second to 360 make for some nice smooth rolls.

The screenshots below show captures from the OPenPilot GCS software version 14.01 and the settings required to change to get this to work. I first tried it on my "beater" quad with a CC3D flight controller and liked it so much I put it on my "nice" quad with a Revo FC and Ov3rquad frame. The video below shows the results from these settings on both my CC3D and Revo controlled quads with CCMA set to 90 degrees and the Rate mode "Degrees / second" setting up at around 450-500.

The next thing I want to try is lowering the CCMA to 80 and deg/sec to 360 for the nice, "natural" roll and then go the other way to CCMA = 100 and deg/sec =720. Maybe with these settings I might get in a few double or triple rolls before hitting the ground.

image002 image004 image006 image008