Accelerometer - LIS302
Accelerometer - I2C/SPI - LIS302
Fig. 1 I2C/SPI 3 axis accelerometer
Description:
This board is a motion sensor in the form of a 3-axis, ± 2g/± 8g smart digital output accelerometer. It is based around a ST LIS302DL chip.
It connects to a host with an I2C or SPI bus and has a programmable interrupt generator.
The board can be powered from 2.16 V to 3.6 V.
Note: this chip does not support 5V power supply.
Specifications:
Input voltage2.16 to 3.6V
InterfaceI2C or SPI
Nb axis3
Resolution± 2g or± 8g
Schematic:
C1 and C2 filters the power supply. R5 and C3 filters the power signal to the digital power supply of the chip.
The CS pin select the mode the chip will operate in. If set to 1, it will be I2C, else it is SPI. The signal is pulled high by default. The signal is also available on the SPI bus connector, with JP8. JP8 allows the selection of which chip select line will drive the chip (CS0, 1 or 2). If connected to I2C connector, the signal is high, so the chip will operate in I2C mode.
For I2C mode, the signal SDA and SCK I2C lines are pulled high by R2 and R3, while R7 and R8 protect the lines. R1 and R6 pull interrupt lines INT1 and INT2 high. In I2C mode, R4 keeps the I2C slave address line low. The chip will have address 0x3A.
For SPI mode, CS will put the chip in SPI mode.
S1 allows to connect INT1 and/or INT2 to the interrupt signal of the I2C and SPI connectors. On the SPI connector, JP9 will select which signal is used for the interrupt.
The I2C connector JP1 and JP2 allow the board to be connected to an I2C bus in a chain. JP7 is the connection to the SPI bus. They are all optional.
Fig. 2 I2C/SPI accelerometer schematic
Construction:
The PCB fits on a small double sided board. The LIS302 is soldered on the bottom side. The other components are on the top side.
Fig. 3 I2C/SPI accelerometer layout
Fig. 4 Bottom view
Start with the lowest components, and continue with the higher ones. The LIS302 is delicate to solder, because the pins are underneath the chip. If you don't have specific smd soldering equipment, cover the copper tracks with tin, clean it with copper mesh and solder the chip, while maintaining in place.
Pads 1 to 4 can be drilled to 3mm to fix the board, or put spacers.
| I2C Eeprom Component list |
|---|
| C1, C3: 100 nF C2: 10 uF R1, R4, R6, R9: 100 K R2, R3: 22 K R5: 10 R7, R8: 220 IC1: LIS302DL JP8, JP9: jumper 2x3 S1: microswitch DIP4 JP1, JP2: Connector AMP MT 5pins male (optional) JP7: Connector AMP MT 8pins male (optional) |
How to use / Testing:
To check the board, you need a processor board running the Digital accelerometer tutorial.
Files and links:
Eagle PCB and schematics files for I2C/SPI accelerometer.PDFs of PCB, layout and schematics of I2C/SPI accelerometer.
PIC Tutorials for digital accelerometer.
ST LIS302DL MEMS motion sensor.