Hi, I am currently implementing software/firmware for the PowerSTEP01 chip and discovered a inconsistency in data sheet https://www.st.com/resource/en/datasheet/powerstep01.pdf. For parameter INT_SPEED (section 11.1.11 in datasheet) the equation does correspond to the stated limits.It says:i.e. steps/s = INT_SPEED × (2^−18) ÷ (250×10^−9)For smallest possible INT_SPEED=1 you get the minimum value: steps/s = 1 × (2^−18) ÷ (250×10^−9) = 15.25For largest possible 14 bit value you get the maximum value: step/s = (2^(14+1)−1) × (2^−18) ÷ (250×10^−9) = 499984.74But according to datasheet equation results should be in range 0 < steps/s < 976.5. So what is correct?NOTE: This question and answer originated from a customer support case which was handled by us. We regularly review support cases and add any helpful ones here for all to benefit from.

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Calculate stepss for PowerSTEP01 (and L6480)

Forum|Forum|6 years ago
October 4, 2019
3 replies
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Hi, I am currently implementing software/firmware for the PowerSTEP01 chip and discovered a inconsistency in data sheet https://www.st.com/resource/en/datasheet/powerstep01.pdf. For parameter INT_SPEED (section 11.1.11 in datasheet) the equation does correspond to the stated limits.

It says:

i.e. steps/s = INT_SPEED × (2^−18) ÷ (250×10^−9)

For smallest possible INT_SPEED=1 you get the minimum value:

steps/s = 1 × (2^−18) ÷ (250×10^−9) = 15.25

For largest possible 14 bit value you get the maximum value:

step/s = (2^(14+1)−1) × (2^−18) ÷ (250×10^−9) = 499984.74

But according to datasheet equation results should be in range 0 < steps/s < 976.5.

So what is correct?

NOTE: This question and answer originated from a customer support case which was handled by us. We regularly review support cases and add any helpful ones here for all to benefit from.

Motor Control Hardware

Best answer by Central SUPPORT

You are right, thank you for raising this issue. In fact, there is a typo in datasheet. The correct formula is:

i.e. steps/s = INT_SPEED × (2^−26) ÷ (250×10^−9)

Same mistake applies also to L6480 datasheet :persevering_face: , but at least L6470 datasheet is correct :) . Control logic is the same for all 3 devices.

Mistake in datasheet will be corrected asap. Sorry for the inconvenience.

Central SUPPORTAuthorBest answer

Senior

You are right, thank you for raising this issue. In fact, there is a typo in datasheet. The correct formula is:

i.e. steps/s = INT_SPEED × (2^−26) ÷ (250×10^−9)

Same mistake applies also to L6480 datasheet :persevering_face: , but at least L6470 datasheet is correct :) . Control logic is the same for all 3 devices.

Mistake in datasheet will be corrected asap. Sorry for the inconvenience.