Programming your e-bike controller using the SW900 display unlocks the full performance and customisation potential of your KT controller. The SW900 is one of the most capable and user-friendly displays available for Indian e-bike conversion kits — offering configurable P-settings for speed limits, wheel size, PAS levels, voltage protection, and motor parameters. This step-by-step guide walks through every setting for optimal configuration.
Table of Contents
- SW900 Display Overview
- Accessing P-Settings Menu
- Complete P-Settings Reference
- C-Settings (Advanced Configuration)
- Wheel Size and Speed Calibration
- PAS (Pedal Assist) Configuration
- Frequently Asked Questions
SW900 Display Overview
The SW900 is a multi-function LCD display designed for use with KT (Kunlun Technology) 48V BLDC controllers. It features: speed display (km/h or mph), odometer and trip meter, PAS level indicator (0–5 or 0–9), battery SOC indicator, assist mode settings, and comprehensive parameter configuration through a hierarchical menu system. It communicates with the controller via a proprietary 5-pin UART protocol.
The SW900 is backward compatible with most KT square-wave controllers (2018 onwards) and works with KT sine-wave controllers. It is NOT directly compatible with non-KT controllers (SABVOTON, Votol, VESC require their own displays).
Accessing P-Settings Menu
Method 1 (Hold buttons): With display powered on, simultaneously hold the UP (▲) and DOWN (▼) buttons for 5 seconds. The display enters the P-settings configuration menu. Navigate with UP/DOWN; confirm each setting with POWER button.
Method 2 (If Method 1 doesn’t work): Hold UP + MODE buttons for 5 seconds. Some SW900 firmware versions use this key combination instead. If neither works, try holding DOWN + MODE simultaneously.
Exiting settings: Hold POWER button for 3 seconds or wait 30 seconds without input — the display auto-exits settings and saves all changes.
Complete P-Settings Reference
| Setting | Parameter | Default | Recommended |
|---|---|---|---|
| P01 | Battery voltage | 48 | Match your pack (36/48/52/60/72) |
| P02 | Motor phase angle | 3 | 3 (=120°, standard for most hub motors) |
| P03 | Wheel diameter (inches) | 26 | Match your actual wheel size |
| P04 | Speed unit | 0 | 0 = km/h (India standard) |
| P05 | Speed limit | 25 | 25 (legal) or 99 (for registered vehicles) |
| P06 | Low voltage protection | 42 | 42V (NMC 48V) or 40V (LiFePO4 48V) |
| P07 | Current limit % | 100 | 80–100 (reduce for battery protection) |
| P08 | Throttle mode | 0 | 0=0-5V, 1=1-4V (twist throttle), 2=half-twist |
| P09 | PAS mode | 1 | 1=5-level PAS, 0=no PAS, 2=9-level PAS |
| P10 | Display brightness | 3 | 3–5 for bright Indian sunlight visibility |
C-Settings (Advanced Configuration)
C-settings are accessed by holding MODE + DOWN for 5 seconds. These settings control lower-level controller parameters:
- C1: Motor characteristics (pole pairs — see motor documentation, typically 23 for common 26″ hub motors)
- C2: Speed limit (secondary to P05 — must match)
- C3: Start current (1–9, higher = more aggressive startup). Recommended: 3–5 for smooth city starts
- C4: Driving mode (0=Speed+Torque combined, 1=Speed only, 2=Torque only). Default 0 is best for most uses
- C5: PAS response level (1–5). Higher values increase motor response speed to pedalling
Wheel Size and Speed Calibration
Accurate wheel size configuration (P03) is critical for correct speed display. Verify calibration by comparing displayed speed to GPS speed at a steady 30 km/h on a flat road. If display reads high, decrease P03 by 1 and retest. If display reads low, increase P03 by 1. One increment change affects indicated speed by approximately 3–5%.
Common P03 values for Indian bikes: 20″ folding = P03:20, 24″ step-through = P03:24, 26″ MTB/city = P03:26, 27.5″ = P03:28, 700c hybrid = P03:29.
PAS (Pedal Assist) Configuration
PAS (Pedal Assist System) settings control how aggressively the motor responds to pedalling input:
- PAS Level 0: Motor off — pedal only. Useful for quiet neighbourhoods or very gentle exercise.
- PAS Level 1: Minimal assist (approximately 20% of maximum motor output). Most efficient, longest range. Recommended for flat Indian city roads with good infrastructure.
- PAS Level 2–3: Moderate assist. Good for hilly terrain or carrying loads. Most common setting for Mumbai/Pune mixed terrain.
- PAS Level 4–5: High assist. Throttle-like response from pedalling input. Suited for cargo hauling or riders with limited fitness.
Frequently Asked Questions
My SW900 shows error code E01 or E07. What does it mean?
E01: Motor Hall sensor error — check Hall sensor 5-pin connector connection. E07: Controller over-temperature — allow to cool before riding. E08: Motor over-temperature. E09: Over-current protection — check for motor/phase wire short circuit or reduce current limit in settings.
Can I use SW900 with any brand of controller?
SW900 is designed for KT brand controllers only. It uses a proprietary communication protocol. It will not function with VESC, SABVOTON, Votol, or other brand controllers — those require their own compatible displays.
After changing P-settings, my e-bike won’t start. What do I do?
A mis-set P02 (motor phase angle) causes this. Reset P02 to the default value (3). Also check P06 (low voltage protection) — if set too high, the bike won’t start when battery is slightly depleted. Try connecting a fully charged battery to confirm.
How do I reset the SW900 to factory defaults?
No single-button factory reset exists. Manually return all P-settings to their default values (see the table above). P01=48, P02=3, P03=26, P04=0, P05=25, P06=42, P07=100, P08=0, P09=1, P10=3. Then power cycle.
My SW900 shows incorrect battery level. How to calibrate?
Verify P01 matches your actual battery voltage (36, 48, 52, 60, or 72V). Incorrect voltage setting causes proportionally incorrect SOC display. P06 sets the low-voltage cutoff — ensure this matches your battery chemistry (LiFePO4 vs NMC have different minimum voltages).
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