Connection of Air Pressure Sensor to PICAXE

[eethawkey]

Hello,

I want to connect a MPX4100 air pressure sensor to a PICAXE, how should i go about doing this. Can the MPX4100 output be directly connected to a PICAXE input or does it require BIT BANGING along the way? If it does require this an explanation of what exactly Bit Banging is and how to go about it would be greatly appreciated.

Thanks

 

[goom]

Looks to me that the output is an analog voltage that could be read directly by a Picaxe using readadc or readadc10. Just power the sensor and the Picaxe from the same nominal 5V supply, and use a bit of simple maths to convert to a pressure as shown in the datasheet. You have read the datasheet I assume?
http://www.freescale.com/files/sensors/doc/data_sheet/MPX4100.pdf

 

[Jeremy Leach]

I've not read the datasheet, but it's likely that the output voltage variation will be too small for useful results, if read directly by picaxe ADC. I used a MPX4115 and dual op-amp to apply offset and gain before feeding into an ADC. Tricky setting up though.

However I also think a better solution might be to use a voltage to frequency converter, like the LM331, and then use the picaxe Count command to determine the frequency>voltage>pressure. This solution has inbuilt averaging too.

 

[moxhamj]

The data sheet says 0.3 to 4.9V so it would have an internal amplifier. Connect it directly to a picaxe. It seems like there should be a catch but there isn't. These amplified pressure transducers make it too easy. I've used them myself and they work really well with picaxe.

 

[BCJKiwi]

I guess it depends on the range of pressures in the application.

Sensitivity is 54mV/ kPa
54mV is 0.054/5 ~ 100th of 5V ~ a 10 count on readadc10
There is also a 1ms response time so repeat reads and averaging may be in order if the pressure is not reasonably steady.