Tytera MD-390 DMR portable evaluation

Recent advertising of the Boafeng DM-5 DMR portable prompted a review of available products at the low end of the market.

The Boafeng DM-5 was dismissed on a desk study that revealed that advertisements were misleading and deceptive in that the claimed Tier 2 support was not yet delivered and was not included in the advertised price. Previous experience with Boafeng also factored against that solution.

Tytera have produced several DMR portables, and the MD-380 has gained a good reputation. I borrowed one for a trial, and it performed quite well… well enough to proceed with purchase of an MD-390 which appears to have similar internals but revised packaging to obtain IP67 protection.

The MD-390 was purchased on eBay for $162 delivered. It came with a US power pack (earning bad feedback), programming cable, two antennas, an earpiece mic set, a disk of all sorts of drivers which aren’t needed, out of date CPS software and Chenglish manual. Continue reading Tytera MD-390 DMR portable evaluation

Last update: 31st December, 2016, 2:46 PM

Improving quadcopter stability at very low throttle using Complementary PWM

This article documents a case study in use of Complementary PWM (COMP_PWM) to improve quadcopter stability at very low throttle.

An observation of two quadcopters of 450 size running several releases of Cleanflight and now Betaflight 3.01 is a loss of stability at very low throttle opening.

This is not uncommon for several reasons, and there is ‘airmode’ in both firmwares to address the problem that motors at minimum speed cannot be slowed further. Experience with airmode on Cleanflight up to v1.14.1 was that it raised throttle so much that descents were extremely slow sometimes, certainly never quick, and its use was discontinued.

I have since abandoned Cleanflight due to unresolved flight problems, lack of migration facility from version to version, and the quiet removal of the backup and restore facility.

The objective of this study was to explore the effect of enhanced motor braking with COMP_PWM on basic angle mode loop stability at low rpm.

Test scenario

The study uses a BC3530 1100Kv motor with 11×4.7 SF propeller, F-30A ESC with SimonK (1e4c01782eff85da3971f628a3bd599b7a0725eb) with COMP_PWM enabled.

Tests were conducted with a script that I use consistently with asrg and eLogger to capture current and rpm, and all tests conducted at similar pressure, temperature and humidity, altitude is 700m.

Test results

One of the effects of COMP_PWM is stronger braking of the motor when throttle is reduced. In multi-rotor application, the motor braking under COMP_PWM is dwarfed by the propeller load at maximum rpm, but propeller torque falls as the square of rpm and at lower speeds motor braking becomes more significant.

Above is a graph of the drive response with a non-COMP_PWM response feint overlay. It can be seen at 13s, that under rapid deceleration, the COMP_PWM response differs, lets zoom in on that. Continue reading Improving quadcopter stability at very low throttle using Complementary PWM

Last update: 29th December, 2016, 7:40 AM

Max thrust: Hobbywing XRotor 40A (MkII) vs BLHeli Hobbywing XRotor 40A (MkII) vs SimonK Hobbyking 9261000003 40A

This article documents a comparative thrust test of a stock Hobbywing X-Rotor 40A, Hobbywing X-Rotor 40A with BLHeli firmware and a Hobbyking 9261000003 40A with SimonK firmware on a medium sized motor at wide open throttle (WOT).

Battery is 3S fully charged.

Motor is a Turnigy Propdrive 28-26S 1100kV;

Propeller is a 9×4.7 SF;

Stock Hobbywing configuration

The X-Rotor 40A out of the box then a throttle cal for 1030/2000 performed.

BLHeli configuration

The X-Rotor 40A is configured with BLHeli v14.8 MULTI, default BLHeli config, then a throttle cal for 1030/2000 performed.

SimonK configuration

The Hobbyking 9261000003 40A is flashed with SimonK’s tgy Hobbyking 9261000003 40A (1e4c01782eff85da3971f628a3bd599b7a0725eb) 15/10/2015.

 

Above, the motor and prop used for the test.

Maximum measured thrust results:

  • X-Rotor 40A with stock Hobbywing firmware: 850g;
  • X-Rotor 40A with BLHeli: 870g;
  • Hobbyking 9261000003 40A with SimonK: 950g
Last update: 25th December, 2016, 12:36 PM

AU ordinary power plug, plug packs and extension cord sockets

Electrical items personally imported to Australia (eg eBay purchases) commonly do not comply with some basic mandated safety features that can be checked with a cursory visual examination.

10A Extension cord sets (AS/NZS 3120)

 

Extension cord sets sold in Australia for more than a decade must have two ‘new’ features as in the pic above:

  • insulated live pins (active and neutral); and
  • shrouded socket;

Plug tops at less than 20A (AS/NZS 3112:2011)

Plug tops at less than 20A must have insulated live pins (active and neutral), and the earth pin if fitted should be longer to make contact first. Continue reading AU ordinary power plug, plug packs and extension cord sockets

Last update: 25th December, 2016, 8:17 AM

Arduino 1.6.12 – adding Optiboard boards.txt

Optiboot is the default bootloader for Arduino Uno, and I use it other Arduinos (eg Nano) for all the good reasons Arduino put it on Uno.

To make that work conveniently, I append the Optiboot boards.txt file to the Arduino distribution.

Above is a screen dump of the options added by the appended file. Continue reading Arduino 1.6.12 – adding Optiboard boards.txt

Last update: 23rd January, 2017, 5:18 PM

BLHeli Hobbywing XRotor 40A (MkII) vs SimonK Hobbyking 9261000003 40A

This article documents a comparative test of a Hobbywing X-Rotor 40A with BLHeli firmware and a Hobbyking 9261000003 40A with SimonK firmware.

The motor is an inexpensive BC3530-14 1100kV motor loaded with a 11×4.7″ slowfly Gemfan propeller, power input to the drive is a little over 300W at wide open throttle.

Battery is 3S fully charged.

Tests were conducted with a script that I use consistently with asrg and eLogger to capture current and rpm, and all tests conducted at similar pressure, temperature and humidity, altitude is 700m.

BLHeli configuration

The X-Rotor 40A is configured with BLHeli v14.8 MULTI, default BLHeli config, then a throttle cal for 1030/2000 performed.

SimonK configuration

The Hobbyking 9261000003 40A is flashed with SimonK’s tgy Hobbyking 9261000003 40A (1e4c01782eff85da3971f628a3bd599b7a0725eb) 15/10/2015.

FET dead times are set rather high at 2000s to be compatible with the slower F40-A. Previous tests have indicated that 1200µs dead time for high and low FETs suits the 9261000003.

Test results

Above, the test run of Hobbywing X-Rotor 40A with BLHeli v14.8 firmware. Continue reading BLHeli Hobbywing XRotor 40A (MkII) vs SimonK Hobbyking 9261000003 40A

Last update: 25th December, 2016, 7:25 AM

BLHeli 14.8 damped light and active freewheeling

Aficionados of BLHeli call out the benefits of “damped light” and “active freewheeling”, terms coined by BLHeli’s author.

Since these are terms invented by BLHeli, so you might wonder whether they are truly innovative or just marketing hype for existing techniques.

Lets go to the BLHeli manual for an explanation.

Pwm damped light mode adds loss to the motor for faster retardation. Damped light mode always uses high pwm frequency. In damped light mode, two motor terminals are shorted when pwm is off

Taking the last statement first, in fact, what happens that as that during the OFF phase of the PWM drive, the high side FETs at both ends of the winding are turned ON. One FET is on for the whole phase, and the other one switches on a short time after its corresponding low side FET turns off. The short time is to allow the low side FET to cease conducting, otherwise both high and low side FETs would conduct at the same time, a current from battery +ve to -ve via the two FETs. There is a corresponding pause at the end of the PWM phase. The time delays allowed depend on the driver circuitry and FET performance, they are specified in the firmware  for a specific and don’t necessarily apply to a pin compatible ESC.

This technique is known in the wider community as COMPLEMENTARY PWM, a very standard technique. Continue reading BLHeli 14.8 damped light and active freewheeling

Last update: 26th December, 2016, 6:20 AM

Hobbywing XRotor 40A (MkII)

Above is the Hobbywing (HW) X-Rotor 40A (BECless) purchased from Hobbyking. It lacks the authenticity markings promoted by Hobbywing, is it a clone? Who knows, it is Chinese.

The X-Rotor 40A was tested in its default configuration, there was no reason to change commutation timing.

Hobbywing enjoys a reputation as a quality product, a cut above the no-name products but his ESC was purchased for about A$16 + shipping, which is really a budget price for a 6S 40-60A BECless (or OPTO) ESC.

Tests were conducted with a script that I use consistently with asrg and eLogger to capture current and rpm, and all tests conducted at similar pressure, temperature and humidity, altitude is 700m.

BLHeli configuration

 

Above is a X-Rotor 40A modified with a permanent C2 interface cable for programming the MCU. The cable has a JST-SH1.0 connector (purchased as HK 258000026) to plug into the after market Tool Stick clone (HK 289000003). The wires from the left are orange , NC, brown and red. (Orange, Red and Brown wires correspond to Black (GND), White (C2D) and Red (C2CK) dots on BLHeli documentation.) A small dot of hot melt adhesive is applied after soldering the wires to the PCB pads, and the cable folded down into the adhesive (to prevent fatigue and breakage of wires). The whole thing will be served over by clear heat shrink.
Continue reading Hobbywing XRotor 40A (MkII)

Last update: 13th September, 2017, 4:04 PM

Arduino 1.6.12 & 1.6.13 AVRDUDE issues

Arduino 1.6.12 has several AVRDUDE related issues.

It comes packaged with AVRDUDE which in my installation is located at C:\Users\owen\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino6\bin\avrdude.exe . This reports itself as “Version 6.3, compiled on Sep 12 2016 at 17:24:16”.

Also relevant is the avrdude.conf file (C:\Users\owen\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino6\etc\avrdude.conf).

This article relates to failures to program a bootloader, and failures to program the application using the very common USBasp.

There were two obvious problems:

  1. a false warning message about setting SCK rate, and fatal failure to contact the target; and (when that is resolved)
  2. failure to verify efuse=0x05.

Continue reading Arduino 1.6.12 & 1.6.13 AVRDUDE issues

Last update: 24th December, 2016, 4:45 PM

Robust programming of Silabs based BLHeli ESCs

This article describes a solution for robust and reliable ‘production’ programming of Silabs based BLHeli ESCs.

The intention is to test and tune the BLHeli configuration, save the configuration in some form, and a scripted solution to programming multiple ESCs now and later replacements with high confidence that they are exactly matching configurations.

There does not appear to be any batch facility for writing flash using the BLHeli bootloader, nor does it appear that BLHeliSuite can save the relevant hex files for later use, so excluding use of the BLHeli bootloader.

The configuration data is held in a block of flash memory labelled EEPROM in the source code. It is not actually EEPROM, the MCU does not have EEPROM, but for consistency the block will be referred to as EEPROM in this article.

Having tested and tuned the configuration using BLHeliSuite, the EEPROM block from the test ESC is read back using Silabs Flash Programming Utility (FPU) and a toolstick attached to the ESC’s C2 interface.

Above, reading the EEPROM block.

The EEPROM block is them merged over the distribution hex file to create a custom hex file for repeated use. Continue reading Robust programming of Silabs based BLHeli ESCs

Last update: 18th December, 2016, 9:04 AM