Driving a charge pump with a Mesa 5i25 stepgen

setp [HMOT](CARD0).stepgen.04.position-scale 10000
setp [HMOT](CARD0).stepgen.04.step_type 2
setp [HMOT](CARD0).stepgen.04.control-type 1
setp [HMOT](CARD0).stepgen.04.maxaccel 0
setp [HMOT](CARD0).stepgen.04.maxvel 0
setp [HMOT](CARD0).stepgen.04.velocity-cmd 0.25

This will generate a 2500 Hz square wave, not 10 KHz


For clarity, I would probable set


setp [HMOT](CARD0).stepgen.04.position-scale 1
setp [HMOT](CARD0).stepgen.04.velocity-cmd 10000

for a 10 KHz chargepump signal

Peter,

Thanks.  I changed those two values and no luck.

Do I need to add a line that adds the charge pump to the base thread?  Section 14.10.2.9 of the 2.8.2 documentation says:

"The Charge Pump should be added to the base thread function."

 

No, the base thread is not needed for hardware stepgens

Let me see if I understand this correctly:

position-scale = (distance) / (# of steps)

Divide the numerator and denominator of the right side by unit time:

position-scale = (distance / s) / (# steps / s)

If position-scale = 1, then:

(distance / s) = (# steps / s)

So a velocity command (distance / s) should generate a waveform of step pulses with a frequency (in Hz) equal to the value of the velocity commanded.

Is the charge pump expecting a 50% duty cycle wave?  Should the steplen and stepspace be bumped up to 50,000 ns each?

T = 50,000 ns + 50,000 ns = 100,000 ns

f = 1 / T = 1 / (0.000 100 000) = 10,000 Hz

The quadrature output mode (mode 2) insures 50% duty cycle

(the step time and step space need to be set to small
values so they do not limit the step rate)

Ah, okay.

Am I missing some sort of virtual connection between the stepgen.04 output and pin 16 of the 5i25 DB25 connector (P3)?