L6470 Run command (relation among MAX_SPPED, MIN_SPPED and SPD values)

[SPD]

Hi, I'd like to use Run command for my stepper motor as follows. How can I set values in registers?

• Maximum speed: 4000step/s
• Minimum speed:  500step/s 
• SPD: 1000step/s

According to the data sheet, I can calculate the values for MAX_SPEED, MIN_SPPED and SPD in (Run command) as follows.

• MAX_SPEED:     4000 x tick / 2^(-18) =4000 x 250 x 10^(-9) / 2^(-18) = 262
• MIN_SPPED:       500 x tick / 2^(-24)  = 500 x 250 x 10^(-9) / 2^(-24)  = 2087
• SPD:                    1000 x tick / 2^(-28) = 1000 x 250 x 10^(-9) / 2^(-28) = 67108

In the data sheet, Run command has Note section. According to the statement, MIN_SPPED <= SPD <= MAX_SPPED but my calculated values are MAX_SPEED < MIN_SPEED < SPD. Even though these settings, does motor rotate correctly?

Note: The SPD value should be lower than MAX_SPEED and greater than MIN_SPEED otherwise the Run command is executed at MAX_SPEED or MIN_SPEED respectively.

      https://www.st.com/ja/motor-drivers/l6470.html 

[Cristiana SCARAMEL]

Hello @SPD and welcome to the ST Community.

The note of the L6470 datasheet you are referring to concerns the real values of the speeds expressed in step/s and not the value of the registers.

So for registers you can use the values you have calculated.

Let me know if these info are useful to you, if yes please "Accept as solution".