Tgy

https://github.com/sim-/tgy

Binary Downloads: http://0x.ca/tgy/downloads/

This tree contains Atmel AVR assembly code for ATmega-based 3-phase sensor-less motor electronic speed control (ESC) boards, originally for Turnigy and similar models. This work is based on Bernhard Konze's "tp-18a" software, which was a port from his earlier personal work to the TowerPro 18A and original (not current!) Turnigy Plush boards. Please see tgy.asm for Bernhard's license.

Patches and comments are always welcome! Let me know how it goes!

Features

• 16MHz operation on most boards
• 16-bit output PWM with full clock rate resolution (~18kHz PWM with a POWER_RANGE of 800 steps)
• 24-bit timing and PWM pulse tracking at full clock rate resolution
• ICP-based pulse time recording (on supported hardware) for zero PWM input control jitter
• Immediate PWM input to PWM output for best possible multicopter response (but NOT where soft start or really any significant current limiting is needed!)
• Accepts any PWM update rate (minimum ~5microseconds PWM low time)
• Optimized interrupt code (very low minimum PWM and reduced full throttle bump)
• Configurable board pin assignments by include file
• Smooth starting in most cases
• Forward and reverse commutation supported, including RC-car style reverse-neutral-forward PWM ranges, with optional braking

Hardware

See http://wiki.openpilot.org/display/Doc/RapidESC+Database and/or https://docs.google.com/spreadsheet/ccc?key=0AhR02IDNb7_MdEhfVjk3MkRHVzhKdjU1YzdBQkZZRlE for a complete list.
Some board pictures here: http://0x.ca/sim/esc/

Notes

• If it breaks, you get to keep both pieces!
• Use at your own risk, and always test first without propellers!
• New Turnigy Plush, Basic, Sentry and Pentium boards (Hobbywing OEM) have all switched to SiLabs C8051F334, d'oh!
• If your ESC has 6 pads and an AVR, it's probably compatible; the pads are MOSI, MISO, SCLK, GND, VCC, and RESET. If it has 4 pads, it is probably a newer SiLabs-based one, for which this code will not work. (Except HK_261000001 which has 4 pads but has an AVR.)
• I build and maintain this in Linux with AVRA (1.3.0 or newer). Patches welcome for AVR Studio APS files, etc.
• The TowerPro/Turnigy Plush type boards typically do not come with external oscillators, which means their frequency drifts a bit with temperature and between boards. Multicopters and RC-car/boat controllers (with a neutral deadband) would probably be better on a board with an external oscillator. The Mystery/BlueSeries boards typically have them, as well as most higher current boards.
• This doesn't yet check temperature or battery voltage. This is not desired on multi-rotor platforms; however, people still want to use this on planes, cars, boats, etc., so I suppose I'll add it.

Building from Source

AVRA 1.3.0 or newer or avrasm2, part of the AVR Tools, should assemble this source. AVRA should also build on a Mac. "make all" will emit a .hex file for every build target; "make binary_zip" will make a release .zip file. There are some other make targets for programming.

In AVR Studio, the Makefile is not supported, and just loading tgy.asm and attempting to build it will not define the constant indicating the board type / build target. You must either edit tgy.asm or add an option for the assembler command line to define the board symbol, unless building the default "tgy" board type. For example, this option should emit the bs_nfet target: -D bs_nfet_esc=bs_nfet_esc Look near the top of tgy.asm for the includes and board information.

WARNING

Never just randomly try build targets until one works, especially not when directly powered from a LiPo! :P Many boards have inverted FET drives and different pin assignments. Toggling one wrong pin can fry multiple FETs. Some boards, like the Mystery 20A ESC, may all look the same on the outside by have different FETs as well. Be careful and check your board before flashing.

Installation

For more information, check out these sites:

http://wiki.openpilot.org/display/Doc/RapidESCs http://wiki.openpilot.org/display/Doc/Flashing+Instructions http://www.rcgroups.com/forums/showthread.php?t=1513678

See warning above! The safest arrangement is to use a current-limited bench power supply, set to a low voltage (6V-7V), for both flashing and initial testing. If the pinout is wrong and causes a short, the current limiting causes the input voltage to drop below the brown-out detection voltage of the MCU, causing all output pins to go high-impedance in hardware, and an automatic reset when the voltage comes back.

If you do not have a current-limited supply, you can improvise by using 4 AA batteries or an old NiCd pack or even a LiPo with a 12V light bulb in series to act as a current limiter. Be careful when touching the board, since it can be quite easy to turn on a FET gate with just your finger. This should be OK if you have a current-limited supply, since it should just reset.

Even if the board appears to be one tested by others, make sure yours has the expected FET pin assignments, inversions, and sense lines! The assignments for each board type can be found in the .inc files, and the actual pin mappings can be found in the first few pages of ATmega8 datasheet. This typically requires a voltmeter and, preferably, an oscilloscope.

When not powered, use a voltmeter to check the path from the MCU pins to either the FET resistors, transistors, or driver chips, and verify that they match the assignments in one of the include files. Then power up the ESC with the original firmware, and check with an oscilloscope the inversions of the same pins. A voltmeter may be used instead when the motor is stopped. Be careful not to short FET pins together! If all voltages are low when the motor is off, nothing is inverted, and the INIT_Px values in the .inc file should be 0 for all of the FET bits.

Older and smaller boards typically use P-FETs and N-FETs in the H-bridge; the P-FETs are typically driven by three NPN transistors, while the N-FETs are driven directly at TTL voltages with just a low resistor. Medium-sized and newer boards have moved to all-N-FET designs, but maintain the NPN transistors, and so have inverted P-FET pins from the MCU. Larger current (>~30A) boards typically have separate FET driver chips, to which the N-FET or P-FET pins may be inverted (but not both, since it would blow up before the MCU initializes).

PWM is usually done on the low side of the H-bridge, where high frequency driving is easiest. If the average voltage increases at the AVR pin as throttle increases, and drops to 0V when stopped, the low-side FETs are not inverted; if average voltage decreases, and rises to 5V when stopped, the low-side FETs are likely inverted. The high side FETs are only switched at every other motor commutation step, and so switch at a lower frequency, and should be off 2/3rds of the time. If at 0V when stopped, and less than 2.5V average when running, the P-FETs are not inverted. If at 5V when stopped, and more than 2.5V when running, the P-FETs are inverted. In the case of inverted an FET group, they should be listed in the INIT_Px values (to turn them ON at boot), and the "on" macros should use clear instead of set instructions. The inverse applies to the "off" macros.

There are four sense lines. The three output phases go through resistor dividers (to bring the voltage down to between 0-5V), and then are connected to ADC channels which can be accessed by the comparator with the ADC multiplexer when the ACME (Analog Comparator Multiplexer Enable) bit is enabled. Some boards use all ADC channels while others put one pin on AIN1 so that the ADC can sample voltages on other ADC channels while the comparator samples that phase. A "center tap" is established with a resistor star and connected to AIN0 on all boards, for detecting the zero-crossing from the motor back-EMF for timing. You can check which pins run to which output phases as they will have the lowest resistance from output phase to AVR pin, and all three will have a common resistance to the AIN0 pin.

Boot Loader

Since the 2012-06-01 release, the pre-built .hex files contain a boot loader that allows for flash and EEPROM reading and writing over the PWM input wire. The main purpose of this boot loader is to support software updates without having to expose the MCU or ISP pads for SPI programming, assuming this version or newer has previously been flashed.

The boot loader is available on all boards which are wired in way that permits two-way communication over the wire. Some ESCs are isolated with an opto-isolator or by components to invert the signal to be compatible with ESCs that do have an opto-isolator, such as ESCs that work with the kda.hex target. Such boards will not be able to use this protocol.

The boot loader uses an implementation of the same wire encoding as the Turnigy USB Linker. This is a simple 9600bps serial to half duplex wire converter that encodes signals in a way that should make it difficult to start a motor, even on an ESC not supporting the protocol, regardless of data sent. However, it is still possible that this could occur, so follow the same precautions as with normal ISP flashing, below.

If the Turnigy USB Linker is not available, it is possible to use an Arduino or MultiWii board as a gateway between (USB and) serial and the wire protocol used by the boot loader. See the ArduinoUSBLinker project by Chris Osgood: https://github.com/c---/ArduinoUSBLinker

Boot Loader Fuses

Since the 2012-09-30 release, long periods of high PWM input while disarmed will cause a jump to the boot loader, if present. Since the 2013-04-24 release, this became detangled from the included boot loader (BOOT_JUMP vs BOOT_LOADER), so other boot loaders may be used instead.

As a result of the automatic jumping, it is not n