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MPL3115A2 - Error reading altitude

Question asked by Michele Santucci on Apr 15, 2015
Latest reply on Apr 23, 2015 by Michele Santucci

Hallo,

 

I'm trying to read altitude data from MPL3115A2 but I'm stuck into a strange error.

 

I'm able to read and write values on registers trough I2C interface indeed I can read correctly the ID value (0xC4) and I'm also able to write and read back values from any other registers (test made on CTRL_REG1, PT_DATA_CFG).

 

I'm following the Quick Setup procedure in MPL3115A2 datasheet (pag 10, polling mode) I collected the values from:

OUT_P_MSB,

OUT_P_CSB,

OUT_P_LSB,

OUT_T_MSB,

OUT_T_LSB

 

The OUT_T_xx values seems correct since they can be converted to a float value around 24 degrees (that's a reasonable temperature value in the test environment).

The problem arise with OUT_P_xxx values . OUT_P_MSB is always set to 0xFF value ... I've not investigated yet trough oscilloscope but it seems like the IC it's

not correctly replying to the read request (but just for the first byte value since CSB and LSB values are not fixed but variates around a steady value).

 

Typical values collected from T registers are: 0x18A0

Typical values collected from P registers are: 0xFFC5C0

 

Best Regards,

Michele Santucci

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