What’s this 4k/4k Mode And MultiShot?

If you haven’t tried 4k/4k with multishot yet, or something even faster, DUDE you are missing out big time. Go upgrade your favorite rig right now! I’ll get into details, but generally speaking the improvement in responsiveness is similar to the improvement pilots feel when upgrading from PPM to SBus. Yes, it’s that good! After upgrading, I immediately felt my comfort zone had expanded and that I was willing to go faster and execute exit/save maneuvers much later. Other friends who have recently tried these upgrades have expressed similar opinions. So please, don’t be afraid to upgrade with these new software settings, you will fly better with less latency.

What are these strange new things?

Multishot – a new ESC protocol that is an order of magnitude faster than the original OneShot.

You can download Multishot here, thank you RS2k! https://github.com/rs2k/raceflight/wiki. Once you have dowloaded the .hex files, flash your ESCs through BL Heli Suite and select “custom” or “other” for the firmware file. I’ve flashed this firmware on LittleBee20s, LittlBee30s, and UBad30s.

4k / 4k Mode – The first number describes your flight controller’s looptime. The second number describes refresh rate of the signal that is being sent from the flight controller to your motor speed controllers. It is possible to run both of these values faster than 4k/4k mode, if you’re running a Dodo or similar F3 processor 4k is the limit. If you’re running an F3 flight controller that uses the SPI bus like the Lumenier Lux, then you can run up to 8k. The motor refresh rate is limited by the processor that is on the ESCs. As I write this, the F390 what everyone is moving toward to get the best performance. DYS XM20, XM30, LittleBee30, and UBad30 ESCs all use this chip. The F390 are fast and can support 4k or faster.

LB20s and other ESCs unfortunately use the slower, previous generation F330 processor. I have it’s recommended to run 4k/2k mode on the older F330 ESCs. However, I’m mean to my electronics and tested 4k/4k mode today with a Dodo and LittleBee20s. I flew five or six packs and had no issues. My opinion is, go for it!

To setup 4k/4k mode you simply need to make the following changes:
1. Upgrade to Betaflight 2.6 or later. Get it here (thank you Boris!): https://github.com/borisbstyle/betaflight/releases/
2. Change looptime to 250 in the Cleanflight settings menu
3. Enter CLI, “set use_multishot=on” or “set use_multishot=yes”
4. In CLI type, “set pid_process_denom = 1”

PID Process Denom is a variable that sets your motor refresh rate. The equation that is used is, motor rate = looptime_rate / pid_process_denom. Since you set your looptime to 250 micro seconds (4000 hz), motor rate is also 4k when PID process denom=1.

I hope this article helps you try out the latest stuff!! Here’s my video from a fun session today where I tried out some other new moves with my Speed Addict 210. Please enjoy =)


Drone Pilot Video Feed vs. GoPro Footage

What do drone pilots see while they are racing? It’s a low latency analog video signal. Typically the displays in our goggles are also low resolution and the pilot cameras only have 600 vertical lines of resolution. That’s far less than your 1080 or 4k TV at home! This video compares the HD GoPro footage to the feed that we see while flying. The GoPro is only used to make videos after we’re done with a flight.

This was also the maiden for the ShenDrones Pod Prototype. I decided to try the Kiss FC and Kiss 24A ESCs in this build. Although it was easy to setup and flew well, I prefer Multishot and 4khz mode on Betaflight. The Kiss FC with oneshot42 had more latency between my stick command and the motor’s response. However, if I were to compare the Kiss setup to my old Betaflight rigs with OneShot125, I would definitely go for Kiss. I’ll play more with the Kiss FC to tune rates, but that latency will never go away unless multishot is ported to the Kiss FC…pretty please Felix?

How to Make Your Own FPV Antennas

I’ve been making my own 5.8 antennas for a few months now.  Big thank you to David at RCExplorer.se for his how-to and online calculator for antenna element length.  I mostly followed his instructions, but modified the antenna element geometry so each element has 10mm to solder directly to the coax braid.  Also, thanks to Bruce at RC Model Reviews for his how-to video!

I designed these antennas for the frequency I fly on, Boscam7 5.9ghz.  My friendly RF Engineering colleague helped me measure return loss on a couple of my antennas and also compared them to the popular Immersion Fatshark Spironet antennas.  The Spironets came in at 13db as advertised.  I was surprised that mine measured 15db!  Wow.  In real testing, my antennas do perform well, even behind trees at Baylands park.

Material List

  • cheap RG402 coax cable from ebay
  • antenna elements are made from telephone wire which can be found at Home Depot by the foot
  • coax connectors are regular SMA, solder-on for RG402 coax, purchased from Ebay
  • The coax cable braid is very brittle after it’s been soldered.  I had several antennas break where the shielding meets the SMA connector.  Fix?  Add hot glue at this location and heat shrink over it.  Problem solved, antennas have been rock solid since then. 
  • I like to cut the coax wire length to 1*lambda.  This creates a shorter antenna that will be less likely to snag an air-gate or tree branch.

How to Setup a 19" TV for your FPV Base Station

I purchased an Insignia 19″ LCD from my local Best Buy, today. It was on sale for $100. I’m not sure how it will behave with static/blue screen and am expecting to have some issues on the edge of my video TX capability. Thankfully, I have RTH set up on all of my devices. Setting the TV up for FPV was pretty simple, the longest step was making a tripod mounting bracket.

Required Material

Insignia 19″ TV NS-19E310A13

– 5.5mm diameter DC plug

– Wireless video receiver (I’m using V2 of this one from readymaderc)

– 12V battery, I’m using a 5000mah 3S lipo pack

– Tripod, I’m using the heavy duty Bower tripod available here Fry’s

Wiring Steps

– provide power from your 12V battery to the 5.5mm DC jack plug. Center pin is positive.

– velcro your receiver to the back of the TV, wire video out from the receiver to video in on the TV

– provide power to the wireless receiver, you can split power from the same battery if you like

Mounting to Tripod

– I designed mounting bracket that screws into the 3″x3″ VESA hole pattern on the back of the TV. The bracket is compatible with the four M4 screws that come with the TV’s base.

– Bower says this is a “Universial” tripod mount, but I believe the square tripod adapter geometry has not been standardized. If you plan on using this with a non-Bower tripod, please compare your tripod adapter geometry for compatibility

– Bower tripod geometry: 32mm square at base, 38mm square on top. 8mm height between top and base.

– If you’re interested in a bracket, please email me. I will start selling them for $10, shipped to the USA via USPS.

– Bracket is compatible with other televisions that also use the 3″x3″ VESA hole pattern.

How to Set Up Manual Pitch Control in Position Mode on a Tarot Gimbal

This guide will help you setup manual pitch control, in position mode, on your Tarot 2-axis gimbal.

* Tarot Manual http://www.jetcat.it/files/tarot_gopro_gimbal.pdf
* Download Tarot software to upgrade firmware: http://www.kingwjg.com/ZYX/Gopro.rar

1. Download and install the Tarot software on your PC
2. Upgrade firmware on the control board and motor board to 1.3 following instructions in their manual
3. In Tarot’s software, change the default RC pitch control from “rate” to “position” mode. After you do this, you will not be able to control the pitch or roll “home” positions using the Tarot software. When you are in position mode, the home positions can only be set by your transmitter. Alternatively, your home position can be set by the flight computer.

4a. If you want to control the home positions using your Naza controller, follow my video, below.
4b. If you want to control the home positions for pitch and roll using your radio transmitter, watch the video but route T and R directly to the signal pins on channels of your RX that you wish to use for pitch and roll. Route the ground pin from the Tarot to the ground pin on one of the RX channels.

General Tips
1. You do not need to send T and R through a flight computer. I am only suggesting it for people who have seven channels, or less.
2. Once you change the RC mode to “position” you will not be able to control the home positions for pitch and roll through Tarot’s software. This is normal.
3. The port for the tarot main board is on the side with more connectors. The motor controller connector is by itself, on the opposite side.
4. If you are using the gopro hero3 USB cable, it requires a 5V source. Do not send 12v to your hero3, it will not charge and will probably enter the dreaded hero3 frozen state.
5. Changes made in the Tarot software do not get saved to the board until you hit the “flash” button
6. When upgrading your firmware, the manual is pretty good. After you click the “upgrade firmware button” you need to turn on the Tarot Gimbal. The manual implies this, but is not totally clear. The UI will tell you that firmware is upgraded after a few seconds.