u/Ok-Eggplant-723

Some people say it’s useless, and some even call it AI slop.

But I’m just building what I want to build.

A MAX6 G2 and motor equipped with a water-cooling system.

A high-voltage power amplifier running new firmware with more features, working without the stock Traxxas ESC.

It’s getting a little closer to completion.

Just to make this happen, I burned out three Traxxas LED amplifiers, pushed ChatGPT hard, and even got help from Claude.

I also had to study the datasheet for an MCU I had never even seen before, the FR2311, and use a TI LaunchPad for the first time.

I tried this, tried that, went around in circles quite a bit, but seeing the clean final result makes all the effort feel worth it haha.

This is a test video.

Because of the modification, one of the lights has its low and high beams reversed.

The rear yellow position light is also not working because of a broken wire, but the amplifier itself is working properly.

The amplifier is connected to the PPM signal line from the receiver, 6V, and GND, plus only the 6S battery power input.

No Traxxas ESC, Traxxas transmitter, or Traxxas receiver is being used. It works with just the amplifier and the DUMBO RC radio system.

Here is how it works.

Just like the stock amplifier, the push button changes between three light modes.

If you click the button once and then hold it for about 5 seconds, the lights blink and the amplifier averages and saves the throttle neutral position.

If you double-click the button quickly and then hold it for about 5 seconds, the lights blink again and the throttle direction is reversed.

The brake lights are linked to the transmitter throttle.

The brake lights do not turn on while reversing.

The 3-stage lighting mode can also be changed using channel 5 on the transmitter.

The code is almost finished, but the FRAM write-protection issue on the FR2311 chip took some time.

Claude found and solved the problem in one minute, even though ChatGPT couldn’t figure it out lol.

Now I just need to finish the wiring and repair the broken LED wire, and it will be done.

After opening and testing a damaged unit, I found that this amplifier is not just a simple LED driver. It has its own MCU inside, which appears to be an MSP430FR2311, and it controls the LED outputs through multiple MOSFETs.

Here are some of the things I confirmed so far.

The LED ports use a constant positive voltage rail, around 16V, and the amplifier switches the negative side through MOSFETs. So the LEDs are controlled by low-side switching.

Each LED port has three pins. On the A/B/C/D ports, one pin is the constant positive output, while the other pins are switched negative outputs.

The brightness control does not appear to be PWM-based. Instead, the brightness seems to be handled through different resistor paths inside the LED units themselves. For example, the rear light uses separate outputs for the dim tail light and the brighter brake light.

The amplifier needs two separate power inputs. One is battery voltage for the LED power side, and the other is a low-voltage supply for the internal control circuit. In my tests, the LED power side worked from 2S to 8S, and the control side worked from about 3.3V to 6V.

Important warning: applying battery voltage directly to the low-voltage control power input will damage the amplifier.

The ESC communication lines are also interesting. The yellow wire appears to be a data line, and the orange wire appears to be a sync/clock/heartbeat style signal. From logic analyzer captures, the yellow line seems to carry data at around 200 kbps, while the orange line outputs a roughly 100 kHz square wave pattern.

I also traced the MSP430FR2311 pin connections on the board. This is my current traced pin map:

Pin 1 - Q2 / A port headlight low beam

Pin 2 - Q1 / A port headlight high beam

Pin 3 - Programming pin / TEST, SBWTCK

Pin 4 - Programming pin / RST, SBWTDIO

Pin 5 - +3.3V

Pin 6 - GND

Pin 7 - Connected to a 2-pin component/connector, function not confirmed yet

Pin 8 - Push button input

Pin 9 - Unknown

Pin 10 - Unknown

Pin 11 - Q7 / D port rear position light

Pin 12 - Q8 / D port reverse light

Pin 13 - Not connected

Pin 14 - Not connected

Pin 15 - Q5 / B port search light low beam

Pin 16 - Q6 / B port search light high beam

Pin 17 - Q3 / C port brake light

Pin 18 - Q4 / C port tail light

Pin 19 - ESC signal line / orange wire

Pin 20 - ESC signal line / yellow wire

I also confirmed that the original MCU firmware was read-protected, so I could not back it up. After erasing the chip and programming my own test firmware, I was able to control the LED output MOSFETs directly.

My current goal is to make the original Traxxas LED amplifier work without the Traxxas ESC, by reading receiver PPM/PWM signals directly and controlling the lights with custom firmware.

This is still a work in progress, but I thought it might be useful to share for anyone else trying to understand, repair, or modify these LED amplifiers.

If anyone has more information about the Traxxas ESC-to-LED amplifier communication protocol, I’d be very interested to compare notes.

After opening and testing a damaged unit, I found that this amplifier is not just a simple LED driver. It has its own MCU inside, which appears to be an MSP430FR2311, and it controls the LED outputs through multiple MOSFETs.

Here are some of the things I confirmed so far.

The LED ports use a constant positive voltage rail, around 16V, and the amplifier switches the negative side through MOSFETs. So the LEDs are controlled by low-side switching.

Each LED port has three pins. On the A/B/C/D ports, one pin is the constant positive output, while the other pins are switched negative outputs.

The brightness control does not appear to be PWM-based. Instead, the brightness seems to be handled through different resistor paths inside the LED units themselves. For example, the rear light uses separate outputs for the dim tail light and the brighter brake light.

The amplifier needs two separate power inputs. One is battery voltage for the LED power side, and the other is a low-voltage supply for the internal control circuit. In my tests, the LED power side worked from 2S to 8S, and the control side worked from about 3.3V to 6V.

Important warning: applying battery voltage directly to the low-voltage control power input will damage the amplifier.

The ESC communication lines are also interesting. The yellow wire appears to be a data line, and the orange wire appears to be a sync/clock/heartbeat style signal. From logic analyzer captures, the yellow line seems to carry data at around 200 kbps, while the orange line outputs a roughly 100 kHz square wave pattern.

I also traced the MSP430FR2311 pin connections on the board. This is my current traced pin map:

Pin 1 - Q2 / A port headlight low beam

Pin 2 - Q1 / A port headlight high beam

Pin 3 - Programming pin / TEST, SBWTCK

Pin 4 - Programming pin / RST, SBWTDIO

Pin 5 - +3.3V

Pin 6 - GND

Pin 7 - Connected to a 2-pin component/connector, function not confirmed yet

Pin 8 - Push button input

Pin 9 - Unknown

Pin 10 - Unknown

Pin 11 - Q7 / D port rear position light

Pin 12 - Q8 / D port reverse light

Pin 13 - Not connected

Pin 14 - Not connected

Pin 15 - Q5 / B port search light low beam

Pin 16 - Q6 / B port search light high beam

Pin 17 - Q3 / C port brake light

Pin 18 - Q4 / C port tail light

Pin 19 - ESC signal line / orange wire

Pin 20 - ESC signal line / yellow wire

I also confirmed that the original MCU firmware was read-protected, so I could not back it up. After erasing the chip and programming my own test firmware, I was able to control the LED output MOSFETs directly.

My current goal is to make the original Traxxas LED amplifier work without the Traxxas ESC, by reading receiver PPM/PWM signals directly and controlling the lights with custom firmware.

This is still a work in progress, but I thought it might be useful to share for anyone else trying to understand, repair, or modify these LED amplifiers.

If anyone has more information about the Traxxas ESC-to-LED amplifier communication protocol, I’d be very interested to compare notes.

ESC: HOBBYWING MAX6 G2 with custom water cooling

Motor: ESQ 2200KV with a water jacket

Weight: 9.8 kg, including coolant and batteries

Custom VITAVON oil-circulating rear axle

I’m currently trying to make the LED amplifier work with the MAX6 as well, by overwriting the program inside the FR2311 MCU in the Traxxas LED amplifier.

I built an aluminum radiator capable of actual liquid cooling.

I built an aluminum radiator capable of actual liquid cooling.