PAJ7620 gesture sensor: specs and pinout
A module built around the PAJ7620U2 chip, which has an infrared LED and a small image sensor and recognises 9 hand gestures (up, down, left, right, forward, backward, clockwise circle, counter-clockwise circle, wave), read over I2C. The figures here are for the chip, not the module board.
Specs
| Spec | Value | Source |
|---|---|---|
| Supply voltage (VDD) | 2.8 V to 3.6 V | source Key Parameters, p.1 |
| I2C and interrupt pin voltage (VBUS) | 1.8 V to 3.3 V | source Key Parameters, p.1 |
| LED supply voltage (VLED) | 3.0 V to 4.2 V | source Key Parameters, p.1 |
| Supply current, operation state | 2.82 mA (standby 1: 2.3 mA; standby 2: 1.5 mA) | source Key Parameters, p.1 |
| Gesture detecting range | 5 cm to 15 cm, view angle 60 degrees diagonal | source 1.1 Gesture Mode, Table 1, p.4 |
| Gesture speed | 60 to 600 degrees/s in Normal Mode; 60 to 1200 degrees/s in Gaming Mode | source 1.1 Gesture Mode, p.4 |
| Gestures recognised | 9 (move up, down, left, right, forward, backward, circle clockwise, circle counter-clockwise, wave) | source 1.1 Gesture Mode, p.4 |
| Interface | I2C up to 400 kbit/s for gesture mode; 4-wire SPI for image mode | source Key Features, p.1 |
| Operating temperature | -40 C to 85 C | source 4.2 Recommended Operating Condition, p.11 |
| Absolute maximum VDD | 4 V | source 4.1 Absolute Maximum Ratings, p.11 |
Power
| Value | Source | |
|---|---|---|
| Supply | VDD 2.8 V to 3.6 V; VLED 3.0 V to 4.2 V; VBUS 1.8 V to 3.3 V | source Key Parameters, p.1 |
| Current | 2.82 mA in operation state | source Key Parameters, p.1 |
Pinout
The module board is not covered by an official document. Its regulator, pull-up resistors, address jumpers, level handling and header order are not documented by a source; check the printed labels on the board. The numbers on this page are for the chip.
| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| 1 | VBUS | Bus power supply | source 1.5 Pin Configuration, Table 3, p.5 (13-pin LGA chip module) | |
| 2 | SDA | I2C data pin (open drain) | source 1.5 Pin Configuration, Table 3, p.5 (13-pin LGA chip module) | |
| 3 | INT_N | Interrupt pin, active low (open drain) | source 1.5 Pin Configuration, Table 3, p.5 (13-pin LGA chip module) | |
| 4 | TESTMD | For module test only | source 1.5 Pin Configuration, Table 3, p.5 (13-pin LGA chip module) | |
| 5 | SCL | I2C clock pin (open drain) | source 1.5 Pin Configuration, Table 3, p.5 (13-pin LGA chip module) | |
| 6 | GND | Ground | source 1.5 Pin Configuration, Table 3, p.5 (13-pin LGA chip module) | |
| 7 | GPIO3 (SPI_DATA) | SPI mode: data out of SPI master; GPIO mode: GPIO | source 1.5 Pin Configuration, Table 3, p.5 (13-pin LGA chip module) | |
| 8 | GPIO2 (SPI_SCK) | SPI mode: SCK signal of SPI master; GPIO mode: GPIO | source 1.5 Pin Configuration, Table 3, p.5 (13-pin LGA chip module) | |
| 9 | GPIO1 (SPI_nCS) | SPI mode: chip select, active low; GPIO mode: GPIO | source 1.5 Pin Configuration, Table 3, p.5 (13-pin LGA chip module) | |
| 10 | GND | Ground | source 1.5 Pin Configuration, Table 3, p.5 (13-pin LGA chip module) | |
| 11 | VLED | LED power input | source 1.5 Pin Configuration, Table 3, p.5 (13-pin LGA chip module) | |
| 12 | VDD | Main power supply | source 1.5 Pin Configuration, Table 3, p.5 (13-pin LGA chip module) | |
| 13 | GPIO0 (SPI_MCLK) | SPI mode: external clock input for SPI; GPIO mode: GPIO | source 1.5 Pin Configuration, Table 3, p.5 (13-pin LGA chip module) |
Build with it
Project ideas for the PAJ7620 gesture sensor. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.
- Gesture name on a display: The chip works at 3.3 V (VDD 2.8 V to 3.6 V) on I2C, matching the ESP32. The OLED shows the name of the last gesture seen, up to 15 cm away. Only gesture codes are read; no images are kept.
- Gesture-controlled LED brightness: Up and down gestures raise and lower a PWM value on an ESP32 pin driving an LED through a resistor from the packs. Learning project.
- Left and right dodge game: Left and right gestures move a block on the OLED. The sensor's read-out is by I2C, so it takes two ESP32 pins plus the interrupt pin.
Common mistakes
- Powering the chip from 5 V: VDD is 2.8 V to 3.6 V and the absolute maximum is 4 V (source: link, sections 4.1 and 4.2). Check how the module board supplies the chip before using 5 V.
- Gesturing outside the working range: the detecting range is 5 cm to 15 cm with a 60 degree diagonal view angle (source: link, section 1.1).
- Moving the hand too fast or too slow: gesture speed is 60 to 600 degrees/s in Normal Mode and 60 to 1200 degrees/s in Gaming Mode (source: link, section 1.1).
Not covered by the official source
- The I2C device address is not stated in the text sections read, so it is left out.
- The recommended operating conditions are not stated clearly in the maker's table; supply ranges are from the Key Parameters table on page 1. Check the datasheet.
Sources
- link (PAJ7620U2 General Datasheet, PixArt Imaging, Version 1.0, 29 Mar 2016; verbatim maker PDF on Seeed's host)