Tongsheng Motor Programming & Settings Guide: How to Customize Your E-Bike Power Delivery

Tongsheng mid-drive motors (TSDZ2 and TSDZ8) are fully user-programmable — no dealer visit required. You can adjust power delivery, torque sensitivity, pedal assist levels, and speed limits using either the factory software or the popular Open Source Firmware (OSF). This guide walks you through the settings that matter most and shows you how to apply them safely, including what to do when something doesn’t work as expected.

User vs Dealer Programming: What You Can Do Yourself

Tongsheng motors ship with a factory firmware that allows basic parameter adjustments through a Windows-only configuration tool (Tongsheng TSDZ2 Programming Tool). You can change wheel size, speed limit, battery voltage, and current limits without any special hardware beyond a USB-to-Serial adapter (e.g., FTDI232) and the programming cable sold by Tongsheng or third-party vendors.

The open‑source firmware (OSF) goes much further — it unlocks torque‑sensor calibration, custom power ramps, regen braking profiles, and display‑specific menus. OSF is a free replacement firmware that runs on the original motor controller and works with several popular displays (850C, SW102, Kunteng). You must flash the motor’s microcontroller yourself using a programming cable and a Windows or Linux computer. This is a one‑time process; after that, all settings are changed via the display or the configuration tool.

Bottom line: If you want only speed limit and basic current adjustments, use the factory tool. If you want fine‑grained control over how the motor delivers power, switch to OSF.

Installing Open Source Firmware (OSF) on Tongsheng Motors

Warning: Flashing firmware rewrites the motor controller. A bricked motor is rare but possible if you interrupt the process. Follow each step exactly.

What You’ll Need

• Tongsheng TSDZ2 or TSDZ8 motor
• Programming cable (Tongsheng specific or a custom FTDI-based cable)
• Windows PC (or Linux with ST-LINK tools) with USB port
• Latest OSF binary from the eco‑ebike GitHub repository (ST‑link version for the motor type)
• ST-Link/V2 programmer (clone is fine) — this is the typical flashing method

Steps to Flash

1. Connect the ST-Link to the motor’s SWD pads.
   Locate the 4‑pin SWD header on the motor controller board (under the plastic cover). Use jumper wires to match SWDIO, SWCLK, GND, and 3.3V on the ST-Link. Double‑check polarity — reversing power can damage the board.

2. Install ST-Link utility software (STM32 ST-LINK Utility on Windows, or stlink-tools on Linux).

3. Download and open the OSF .hex file.
   Select the correct variant for your display and hardware version (e.g., TSDZ2-850C-v2.hex).

4. Connect the ST-Link to your computer, apply battery power to the motor (48V or 52V recommended), then run the flash.
   Press “Connect” in the utility, then “Program & Verify.” Flashing takes about 30 seconds.

5. Disconnect power and ST-Link, reassemble the motor, and turn on the bike.
   The display should boot with OSF logos and menus.

Branch: What to Do If the Screen Stays Blank

A blank display after flashing is the most common hiccup. The next step depends on what you see:

• If the display lights up but shows no text — you likely selected the wrong firmware variant for your display type (e.g., using an 850C hex on an SW102). Re-flash with the correct variant.
• If the display stays completely dark (no backlight) — check the display cable connection at both ends, and verify that the motor’s 5V output is alive by measuring voltage on the display connector. If voltage is present, the display itself may need a separate firmware update (some SW102 units require a Bluetooth‑based bootloader).

Do not disassemble the motor again until you’ve ruled out a simple cable issue. A loose connector is far more likely than a bricked controller.

Adjusting Power Delivery: The Most Impactful Settings

Once OSF is installed, the most impactful settings live in the display menus. Here’s what each does and how it affects your ride.

Parameter	Where to Find It (850C Display)	Effect on Power Delivery
ADC Pedal Torque Sensor Calibration	Advanced Settings → Torque Sensor	Adjusts raw sensor values to actual pedal force. Wrong values cause jerky assist or no assist.
Motor Current Limit	Motor Settings → Max Current	Governs peak torque from the motor. A 48V system with 18A limit = ~864W peak. Higher current = stronger hill climbs but more battery drain.
Assist Level Factor	Assist Profiles → Level 1-5	Multiplier on base power per level. Level 1 typically 0.3, Level 5 up to 1.5.

Tune so Level 1 feels like gentle push, Level 5 is full power. |
| Power Ramp Rate | Advanced Settings → Ramp | Controls how fast the motor ramps up when you start pedaling. Lower numbers (e.g., 50 ms) give instant response; higher numbers (500 ms) smooth out lurches. |
| Wheel Circumference | Settings → Wheel Size | Must match your tire diameter for accurate speed and distance display. Use the rolling‑circumference method (mark tire, roll one revolution, measure). |

Rider outcome: A well‑tuned torque sensor makes the motor feel like an extension of your legs, not a light switch. Setting the ramp rate too fast (under 100 ms) can cause wheel spin on loose surfaces; too slow (over 500 ms) feels sluggish when pulling away from stops. For example, a rider who frequently rides on gravel should stay above 200 ms to avoid sudden torque spikes that break traction.

Torque Sensor Calibration – Why It Matters and How to Do It

The torque sensor is the heart of a Tongsheng mid‑drive. It measures how hard you push the pedals and tells the motor how much assistance to add. Calibration translates raw ADC counts into actual Newton‑meters.

Why Calibrate

• Factory values are averaged; each sensor has slight variation.
• An under‑calibrated sensor gives weak assist even on high levels.
• An over‑calibrated sensor causes the motor to surge on light pedal pressure.

Calibration Procedure (OSF)

1. Enter Advanced Settings → Torque Sensor on the display.
2. Set ADC Offset to the value displayed when the pedals are at rest (no weight). Typical range: 100–300.
3. Set ADC Max to the value when you stand on one pedal (simulate maximum force). Common range: 600–1200.
4. Set ADC Dead Zone to a small number (10–20) so that light pedaling doesn’t trigger assist.
5. Save and test ride. If the motor feels too eager, lower ADC Max; if it feels weak, raise ADC Max.

No torque sensor calibration will make the bike feel like a cadence‑sensor e‑bike — either all or nothing. Proper calibration gives the smooth, proportional assist riders expect from a mid‑drive.

Failure Mode: Motor Cuts Out Under Hard Pedaling

Symptom: When you push hard up a steep hill, the motor suddenly stops assisting, then resumes a second later.
Likely cause: The ADC Max value is set too high — higher than the sensor can actually output. The controller interprets the signal as a sensor fault and shuts off assist as a safety measure.
Safer next move: Reduce ADC Max by 100 counts and re-test. If the cutout disappears but assist feels weaker than expected, increase ADC Max in smaller steps (20–30 counts) until you find the sweet spot. A good starting point is 80% of the raw value you recorded while standing on the pedal.

Display Options and Their Role in Programming

OSF supports several LCD displays. The display is where you change most settings day‑to‑day, so choose one that fits your riding and tinkering style.

Display	Features	Best For
850C	Color screen, five assist levels, full OSF menu (torque calibration, battery info)	Riders who want full control from the handlebar without a phone.
SW102	Small monochrome OLED, Bluetooth for some variants, fewer on‑screen menus	Minimalists; settings must be changed mostly via the Bluetooth app (if supported) or by reconnecting to a PC.
Kunteng LCD3	Basic LCD, limited OSF support (no torque sensor calibration on display)	Budget builds or riders who program once and don’t adjust afterward.

All three displays can show real‑time power, battery voltage, speed, and odometer. The 850C is the most common choice for OSF tuning because it exposes every parameter directly.

Confirming Your Settings Are Working

After adjusting any setting, perform a short ride or stationary test to confirm it stuck and behaves as expected:

• Motor starts assisting within 1 second of pedaling — if it delays, check ramp rate and dead zone.
• Assist level 1 gives only a gentle push — if it feels too strong, reduce the assist factor for that level.
• At full throttle (if enabled) you hit the expected speed — if speed cap is 20 mph, the motor should fade at 20 mph, not cut abruptly.
• Battery voltage drops smoothly under load — a voltage sag spike of more than 2V at full current suggests you should lower the max current limit to protect the battery.

Torque sensor verification: After calibration, pedal slowly in place while watching the assist level indicator on the display. The bar or number should rise smoothly from zero as you increase pedal force. If it jumps from zero to full instantly, the dead zone is too low or ADC Max is too low. If it stays at zero until you stomp hard, dead zone is too high or ADC Max is too high.

All settings take effect immediately after saving; no reboot is required. If a change does nothing, revisit the menu path — some parameters (like wheel circumference) only update after a power cycle.

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Tongsheng motor programming gives you the ability to dial in power delivery exactly how you want it — from a whisper‑smooth commuter to a steep‑climbing torque beast. With OSF and a few calibration passes, your e‑bike will feel uniquely yours.

Explore This Topic

• Back to Controller & Display
• Back to E-Bike Motor Programming

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– Fazua Motor Programming & Settings Guide: How to Customize Your E-Bike Power Delivery
– Shimano Motor Programming & Settings Guide: How to Customize Your E-Bike Power Delivery
– Bafang Motor Programming & Settings Guide: How to Customize Your E-Bike Power Delivery
– Bosch Motor Programming & Settings Guide: How to Customize Your E-Bike Power Delivery