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karolalexandersecret
karolalexandersecret
Associate II
January 18, 2018
Question

stpm10 Datasheet current channel calibration register bad description

  • January 18, 2018
  • 1 reply
  • 591 views
Posted on January 18, 2018 at 13:32

Hi,

We are working on power consumption measurement implementing the stpm10 with a Steval IPE017V1. There is some informations missing in the datasheet at config register description about the CHP register. It should be a 8 bits register. 16 bit are assigned for it and the corresponding description is about some other unknown register: CHS

I suppose that this register is for primary and secondary calibration, can someone confirm it and tell us to which of the channel the first and second byte are coresponding ?

Also can you give some precision on where are the LSB and MSB. Do the LSB start at low adress value ?

Thank you,

Alexander

#stpm10
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1 reply

karolalexandersecret
karolalexandersecretAuthor
Associate II
January 31, 2018
Posted on January 31, 2018 at 14:22

Up

We still need information about those registers.

Also i'm trying to calculate true uRMS and iRMS from the corresponding register in stpm10 with the following formulas from the AN2159:

u_rms = (1+R1/R2) * x_u_rms *Vref /(Au * Ku * Kint_comp * Kint * Kdif * len_u * Kut)

i_rms = x_i_rms * Vref/(Ks * Ai * Ki * Kint * Kint_comp * Kdif * len_i)

u_mom = (1+R1/R2) * x_u_mom * Vref /(Au * Ku * Kint_comp * Kint * Kdif * len_u_mom *

Kut)

i_mom = x_i_mom * Vref /(Ks * Ai * Ki * Kint * Kint_comp * Kdif * len_i_mom)

When connecting a 1450watt device to a french power line (237 Vrms, 50Hz) the board give us the following result:

uRMS: 700

iRMS: 828

When trying to find the true voltage, formula give me uRMS = 1.28

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