SparkFun Forums

[rmillqvist]

Any chance of stocking air pressure sensors like the Motorola MPXAZ4115AC6U-ND? I've build a device using a atmega128 board with a 128x128 color display, a EM-406 Gps module and a MPXAZ4115AC6U-ND pressure sensor and a SHT15 temp/hum module, apart from working as a gps it stores all the readings on a sd card. I would like to build more devices measuring barometric pressure so it would be good if you could stock these sensors.
Regards Robert

[thomasb]

I vote for the Intersema MS5534B. It uses a 3-wire digital interface and has an internal 15-bit ADC (0.1mbar resolution). It is very small, and the SMD package is not as hard to solder as it may appear. The "A" part is being replaced by the improved "B" version, so stick with the latter.

http://www.intersema.ch/site/technical/ms5534.php

[NleahciM]

I vote for the Intersema MS5534B. It uses a 3-wire digital interface and has an internal 15-bit ADC (0.1mbar resolution). It is very small, and the SMD package is not as hard to solder as it may appear. The "A" part is being replaced by the improved "B" version, so stick with the latter.

http://www.intersema.ch/site/technical/ms5534.php

Admittedly I have not looked at many pressure sensors - but that one seems a bit odd. First off, the interface is just plain bad. It resembles a hacked up SPI, except it uses the Dout line to signal data being ready, and has no CS pin. I wonder what genius thought up that system? It boggles my mind. Also, it is very dependent on temperature, and it does not do any correcting for temperature - that is left to the end user, though they do have the kindness to include a temperature sensor.

Are all pressure sensors this annoying? Surely not?

[thomasb]

It resembles a hacked up SPI, except it uses the Dout line to signal data being ready, and has no CS pin.

It does not need a CS pin -- that is handled by a special ID bit sequence preamble. It is true that the Dout does not Hi-Z, so if SPI daisy chaining is required, then a Tri-Sate buffer on that pin is required.

The advantage of this digital sensor over the analog solutions is that getting high resolution on the latter usually involves an extremely well designed PCB layout (to minimize noise) to support a high bit count A/D, or an adjunct analog amplifier. In most cases, this sensor requires less hardware and helps hobby apps that use less sophisticated one or two layer board layouts. Lastly, temperature compensation is available using a second order correction scheme (software).

It is different, but works. There are a few hobby apps out there that use it too. For example: http://www.kapelec.com/altiose1.htm

[JC]

This thread talks about the sensor.

http://avrfreaks.net/index.php?name=PNp ... 0ae776d1ec

and this thread:

http://avrfreaks.net/index.php?name=PNp ... 0ae776d1ec