BMP085

BMP085
Status	Experimental
menuconfig	I/O->I2C Master Support->BMP085
Pinning	no
Ecmd	yes
Control6	no
Depends on	ECMD, I2C
Requires	-
Code	https://github.com/ethersex/ethersex/blob/master/hardware/i2c/master/i2c_bmp085.c

Bosch BMP085 and BMP180 barometric pressure sensors

Sensors

• Cheap (about 6 EUR)
• Small
• Precise (Resolution 0.25m, absolute accuracy +-2.5 hPa)
• Digital readout via I2C
• BMP085 and BMP180 are code-compatible, the BMP180 comes in a smaller package

Datasheets

Availibility

Pure sensors

• Digikey

Breakout boards

• JeeLabs
• Sparkfun
• Watterott

ECMD

Command Syntax	Short description
bmp085 temp	Returns the temperature in 0.1°C (16 Bit integer)
bmp085 apress	Returns the absolute pressure in Pa (32 Bit integer)
bmp085 height <p0>	Returns the height in cm. Needs the pressure p0 at NN as parameter (given in Pa, 32 Bit integer).
bmp085 pressnn <height>	Returns the pressure p0 at NN in Pa. Needs the current height in cm (32 Bit integer).

Pressure calculations

• Pressure calculations for the height and pressnn commands are done using the Barometric formula

Precision

• The sensor is sensitive to air turbulences (propellers, fans, loud music)
• The sensor is sensitive to power supply ripple - if not using a battery try to filter it well
• The results will have some noise, filter them with a moving average or other algorithm to get good results